NATURAL HERITAGE STRATEGY · mandates protection of natural heritage features through the municipal...
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1 | Page PLACE PHOTO HERE, OTHERWISE DELETE BOX TERRESTRIAL NATURAL HERITAGE STRATEGY October 2013 GRCA Board Approval, June 13, 2013 – Resolution Number FA 27/13
Transcript of NATURAL HERITAGE STRATEGY · mandates protection of natural heritage features through the municipal...
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PLACE PHOTO HERE,
OTHERWISE DELETE BOX
TERRESTRIAL NATURAL
HERITAGE STRATEGY
October 2013
GRCA Board Approval, June 13, 2013 – Resolution Number FA 27/13
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ACKNOWLEDGEMENTS
Text for this document written primarily by Ken Towle, Terrestrial Ecologist. Appendix 1
text adapted from TRCA (2004). Reviewed by Mark Peacock, Director of Watershed
Services, and Pam Lancaster, Stewardship Technician. GIS analysis and mapping by
Cody Brown, with support by Jeff Moxley. Layout by Julie Verge. All photos by Ken
Towle, except where noted.
Correct citation for this document: Ganaraska Region Conservation Authority. 2013. Terrestrial Natural Heritage Strategy. Ganaraska Region Conservation Authority. Port Hope, Ontario.
(Cover photograph: Aphrodite Fritillary butterfly on New England Aster)
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EXECUTIVE SUMMARY
Historically much of southern Ontario, including the watershed of the Ganaraska Region
Conservation Authority (GRCA), was dominated by forest cover interspersed with
smaller areas of tallgrass prairie and wetlands. Most of these were cleared or drained
for agriculture, leaving a landscape in which remaining natural cover is fragmented.
Threats such as increased predation or parasitism, invasive species, roads,
urbanization, pollutants and climate change are having negative impacts on these areas.
Conservation biology demonstrates that fragmented landscapes tend to support fewer
species and have reduced ecological function. This in turn has a profound impact on the
ecological goods and services we rely on as a society. The recommended approach for
dealing with these issues is to increase natural cover and connect habitat patches
through a natural heritage system. The Ontario Provincial Policy Statement now calls for
municipalities to protect significant natural heritage features and to define natural
heritage systems.
The Ganaraska Region Conservation Authority has modified the methodology developed
by the Toronto Region Conservation Authority to evaluate the status of habitat patches
within the landscape and to use a GIS model to define target areas for a natural heritage
system. Two target scenarios are presented within this natural heritage strategy along
with a summary of threats to biodiversity and recommendations for action. This
document is meant to guide action by the GRCA and to inform the decision making
process within the planning departments of its municipal partners.
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Table of Contents
ACKNOWLEDGEMENTS ................................................................................................................... 2
EXECUTIVE SUMMARY ..................................................................................................................... 3
1. INTRODUCTION .......................................................................................................................... 9
2. HISTORICAL CONTEXT ............................................................................................................... 11
3. TERRESTRIAL NATURAL HERITAGE CONSERVATION ISSUES..................................................... 12
3.1 Habitat Fragmentation ....................................................................................................... 12
3.1.1 Habitat Patch Size ....................................................................................................... 13
3.1.2 Habitat Patch Shape .................................................................................................... 14
3.1.3 Habitat Patch Isolation/Connectivity .......................................................................... 16
3.1.4 The Landscape Matrix .................................................................................................. 17
3.1.5 Habitat Patch Configuration ........................................................................................ 18
3.2 Invasive Species ................................................................................................................... 19
3.3 Roads ................................................................................................................................... 22
3.4 Urbanization ........................................................................................................................ 23
3.5 Agriculture ........................................................................................................................... 24
3.6 Recreational Use ................................................................................................................. 24
3.7 Atmospheric Pollution and Climate Change ....................................................................... 25
4. THE NATURAL HERITAGE SYSTEM CONCEPT ............................................................................ 25
5. POLICY RATIONALE FOR A NATURAL HERITAGE SYSTEM APPROACH ...................................... 27
5.1 Provincial Policy .................................................................................................................. 27
5.2 Oak Ridges Moraine and Greenbelt Plans .......................................................................... 28
5.3 The Ontario Biodiversity Strategy ....................................................................................... 28
5.4 Conservation Authorities Act .............................................................................................. 28
6. THE GANARASKA REGION CONSERVATION AUTHORITY NATURAL HERITAGE APPROACH ..... 30
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6.1. Overview of Approach ....................................................................................................... 31
6.2 Landscape Level .................................................................................................................. 31
6.3 Vegetation Community Level .............................................................................................. 32
6.4 Species Level ....................................................................................................................... 33
7. SUMMARY OF EXISTING NATURAL HERITAGE CONDITIONS .................................................... 35
7.1 LANDSCAPE LEVEL ............................................................................................................... 35
7.1.1 Total Cover of Major Habitat Types ............................................................................. 35
7.1.2 Forest ........................................................................................................................... 35
7.1.3 Wetlands ...................................................................................................................... 36
7.1.4 Meadow/Grassland ..................................................................................................... 38
7.1.5 Beach and Bluff ............................................................................................................ 38
7.1.6 Habitat Patch Conditions ............................................................................................. 39
7.1.7 Patch Size ..................................................................................................................... 39
7.1.8 Patch Shape ................................................................................................................. 40
7.1.9 Matrix Influence ........................................................................................................... 40
7.1.10 Total Habitat Patch Score .......................................................................................... 41
7.2 VEGETATION COMMUNITIES LEVEL .................................................................................... 41
7.2.1 Forests (ELC codes FOM, FOD, FOC, SWM, SWD, SWC, CUP, CUW) ........................... 41
7.2.2 Wetlands (ELC codes SWM, SWD, SWC, SWT, MAM, MAS, FEO, SAS, SAM,SAF) ....... 43
7.2.3 Meadow/Grassland (ELC codes CUM, CUS, CUT, TPO, TPS, SBO) ............................... 45
7.2.4 Beach and Bluff (ELC codes BBO, BBS, BBT, SDO, SDS, SDT, BLO, BLS, BLT) ................ 46
7.3 SPECIES LEVEL ..................................................................................................................... 48
8.0 POTENTIAL NATURAL HERITAGE CONDITIONS ........................................................................ 51
8.1 Introduction ........................................................................................................................ 51
8.2 Target System Scenarios ..................................................................................................... 52
9.0 GETTING THERE FROM HERE: THE STRATEGY ....................................................................... 54
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9.1 Tools for Natural Heritage Protection and Restoration ...................................................... 54
9.1.1 Provincial Policy .......................................................................................................... 55
9.1.2 Public Education .......................................................................................................... 57
9.1.3 Private Landowner Stewardship .................................................................................. 58
9.1.4 Land Acquisition and Securement ............................................................................... 59
9.1.5 Alternative Land Use Options ...................................................................................... 59
9.1.6 Management of Conservation Authority Lands .......................................................... 61
9.1.7 Integration of Terrestrial Natural Heritage with Other Watershed Management
Programs ............................................................................................................................... 62
9.2 Dealing With Specific Conservation Concerns .................................................................... 63
9.2.1 Species at Risk and Rare Species ................................................................................. 63
9.2.2 Grassland Birds ............................................................................................................ 66
9.2.3 Rare Tallgrass Communities......................................................................................... 68
9.2.4 Coastal Zones ............................................................................................................... 70
9.2.5 Climate Change ............................................................................................................ 72
9.2.6 Invasive Species ........................................................................................................... 73
9.2.7 Roads ........................................................................................................................... 74
9.2.8 Recreational Use .......................................................................................................... 75
9.2.9 Urbanization ................................................................................................................ 76
GLOSSARY OF TERMS .................................................................................................................... 77
REFERENCES .................................................................................................................................. 81
APPENDIX 1.................................................................................................................................... 87
USING GIS TO DEFINE THE NATURAL HERITAGE SYSTEM ............................................................. 87
1. Landscape Analysis and the Natural Heritage System Model ............................................... 87
2. Vector Landscape Analysis .................................................................................................... 87
2.1 Patch Size ........................................................................................................................ 89
2.2 Patch Shape .................................................................................................................... 89
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2.3 Matrix Influence .............................................................................................................. 90
2.4 Total Score ...................................................................................................................... 90
3. Value Surface Raster Model ................................................................................................. 91
3.1 Patch Quality (Total Vector Score) ................................................................................. 92
3.2 Forest Interior ................................................................................................................. 92
3.3 Distance from Urban Areas ............................................................................................. 93
3.4 Distance from Roads ....................................................................................................... 93
3.5 Proximity to Natural Areas ............................................................................................. 94
3.6 Proximity of a Wetland to a Forest ................................................................................. 95
3.7 Proximity of a Forest to a Wetland ................................................................................. 96
3.8 Proximity to a Watercourse ............................................................................................ 97
3.9 Proximity to Lake Ontario ............................................................................................... 98
4. Defining a Target Natural Heritage System .......................................................................... 98
5. Using Landscape Metrics as Surrogate Measures of Ecological Health ............................. 106
APPENDIX 2 – ACRONYMS ........................................................................................................... 109
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1. INTRODUCTION
The term “natural heritage” is commonly used across North America and has been
adopted by the Ontario government for use in provincial policy. Natural heritage
“includes geological features and landforms; associated terrestrial and aquatic
ecosystems; their plant species, populations and communities; and all native animal
species, their habitats and sustaining environment” (OMNR 1992). While literally the
term means the nature that we have inherited, the definition above essentially describes
ecosystems and the geological features that support them. Natural heritage includes
biodiversity, which can be defined as the variety of life, as expressed through genes,
species and ecosystems, that is shaped by ecological and evolutionary processes
(OMNR 2005). For the purpose of the Ganaraska Region Conservation Authority
(GRCA), terrestrial natural heritage is analogous with terrestrial biodiversity, taking into
consideration the underlying geological features.
Reasons for protecting biodiversity range from recognizing the intrinsic value of nature,
to the aesthetic and inspirational values it provides, and our responsibilities as global
stewards. However, the simplest answer is that we depend on biodiversity to survive.
Nature and biodiversity provide us with what are now commonly referred to as
“ecological goods and services” such as food, medicines, clean air and water, soil,
erosion control, assimilation of waste and pollutants, recreational opportunities, etc.
These services can have inestimable social and economic values. All life on Earth
depends on healthy, functioning ecosystems. Removal of species components of these
systems amounts to a loss of integrity that could eventually lead to collapse. It also robs
us of potential, both in the form of future resources, and more importantly in relation to
the adaptive capacity of ecosystems in response to environmental change.
In 1992 Canada signed and later ratified the United Nations Convention on Biological
Diversity, committing our nation to conservation and sustainable use. This was soon
followed by the creation of the Biodiversity Strategy for Canada (1995). Ten years later
Ontario responded with its own biodiversity strategy (OMNR 2005) outlining steps that
should be taken at a provincial level. The Ontario Provincial Policy Statement (2005)
mandates protection of natural heritage features through the municipal planning process,
and recommends natural heritage systems as a tool for reaching this goal.
This document is a natural heritage strategy for the Ganaraska Region Conservation
Authority watersheds (Figure 1). It includes an overview of some of the main terrestrial
conservation issues in the GRCA area and outlines a series of steps and a framework
for addressing these. It also includes the methodology and results for defining target
natural heritage systems, and both long and short-term target system scenarios, with a
summary of the changed conditions each would result in. In short, the document is
meant to be both a baseline summary of existing natural heritage conditions and a road
map to direct the GRCA in conserving and improving these for the future.
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It is intended that this document be used to inform planning decisions related to natural
heritage. Specifically in this regard the intent is to work with municipal partners to
determine the degree to which the target natural heritage system scenarios can be
recognized in municipal official plans, and policies developed around protection and
restoration of the ecological features and functions. The GRCA has in turn been
promoting the protection and restoration of natural heritage systems through the
watershed planning process.
Figure 1. Ganaraska Region Conservation Authority Watersheds
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2. HISTORICAL CONTEXT
Prior to the arrival of European settlers the landscape of southern Ontario was
dominated by forest, although early explorers such as Champlain recorded extensive
clearing by aboriginal people in some areas (Larson et al. 1999). The degree to which
aboriginal cultures used fire to clear land is unknown, however given that they relied on
stone tools it is likely that fire was widely used for to create agricultural plots and habitat
for game species (Larson et al. 1999). On dry sand plains this would have helped to
maintain open woodland or prairie and species associated with these ecosystems (Traill
1885, Reznicek 1983, Bakowsky and Riley 1992).
Following the arrival of European settlers the aboriginal population was greatly reduced
and land was rapidly cleared for agriculture and to supply sawmills. By 1920
approximately 90 percent of the original forest had disappeared (Larson et al.1999).
Agriculture failed in areas with predominantly sandy soils such as on the Lake Erie Sand
Plain and the Rice Lake Plains. By the 1920s these areas had become highly eroded,
and blowing sand was everywhere. Large-scale reforestation efforts to stabilize soils in
subsequent decades resulted in widespread pine plantations in areas such as the Oak
Ridges Moraine (Richardson 1944). Overlooked at the time were native tallgrass
prairies and savannas that were historically quite extensive in these sand plains (Catling
et al. 1992).
Although forest cover has increased somewhat in the past 100 years, the great forests of
southern Ontario are gone, and what remains is a patchwork of fragments surrounded
by agricultural lands and urban land use. Whereas most of the forest in pre-settlement
times would have been mature or old growth, present day forests tend to be young or in
early stages of ecological succession (Larson et al. 1999). Tallgrass ecosystems have
been reduced to less than 0.3 percent of their original cover, making them one of the
most threatened ecosystems in Canada (Rodgers 1998). The Passenger Pigeon
(Ecopistes migratorius), whose flocks blackened the skies, and which must have had an
inestimable impact on forest ecology, is extinct. Cougars (Felis concolor) and Timber
Rattlesnakes (Crotalus horridus) have become extirpated. Eastern Wolf (Canis lupus
lycaon), Elk (Cervus canadensis), and Moose (Alces alces) disappeared from much of
the landscape to be replaced by Coyotes (Canis latrans) and White-tailed Deer
(Odocoileus virginianus). Today, largely due to intensification of agriculture and rapid
urbanization, dozens of sensitive species are declining, and have been designated as
threatened or endangered in the province. Meanwhile, invasive species are threatening
to displace native species through competition or predation, and are altering the
structure of ecosystems. All of these concerns are exacerbated by incremental habitat
loss and fragmentation, which are the main drivers behind the global decline of
biodiversity.
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3. TERRESTRIAL NATURAL HERITAGE CONSERVATION ISSUES
There are many threats to terrestrial biodiversity resulting from human activities. These
are problematic because they ultimately affect ecological function within individual
ecosystems and across the landscape. For humans this means the loss or degradation
of important ecological goods and services provided by these systems.
One of the most significant of terrestrial conservation issues in southern Ontario is
habitat fragmentation. This section covers the impacts of habitat fragmentation, and the
conservation concerns related to habitat patch characteristics in a fragmented
landscape, before reviewing some more general conservation issues.
A fragmented landscape where forest cover is now in isolated patches
3.1 Habitat Fragmentation
Habitat loss is a concept that is easily understood and widely recognized as an
environmental concern. On the other hand, the general public seems to be quite
unaware of habitat fragmentation as an environmental issue, despite its major role in the
loss of biodiversity and ecosystem health.
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Habitat loss can include the shrinkage of a particular habitat type by removal from an
outside edge resulting in partial or complete loss, or the perforation of a habitat type by
removal of internal sections. In contrast, habitat fragmentation is a process of breaking
a whole into smaller pieces, such as through bisection (Figure 2). Habitat fragmentation
involves habitat loss, however habitat loss does not necessarily result in fragmentation
(Collinge 2009). A fragmented landscape is characterized by remnant patches of natural
areas surrounded by human land use. This use is typically agriculture or urban, but can
also include large-scale forestry or mining.
The effects of habitat fragmentation on biodiversity are predominantly related to the size
and shape of remnant patches, the degree of connectivity between them, the
surrounding dominant land use matrix, and their configuration in the landscape. The
relevance of each of these is explained below.
Figure 2. The process of habitat fragmentation and loss of interior habitat and species (Kruger).
3.1.1 Habitat Patch Size
The larger a habitat patch is, the higher the diversity of conditions it is likely to contain
(such as slope, aspect, tree maturity, etc.), and therefore the more species it is likely to
support. A large patch can not only help ensure that a species is represented in a given
area, by supporting more individuals (a population) it can help ensure that it remains
there over time. Furthermore, many species are “area-sensitive,” that is, they require
large blocks of habitat for an individual or a pair to survive. Scientists are also learning
that many species have complex behavioural patterns, without which breeding is not
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successful. Populations must be large enough to support the demographics behind
these behaviours (e.g. Norris and Stutchbury 2001). Larger patches are also more likely
to maintain ecological functions and to be sheltered from negative external impacts.
The process of fragmentation reduces the size of habitat patches and therefore limits the
ability of a natural area to support area-sensitive species. These include those that
require large home ranges, such as the large carnivores at the top of the food chain.
Some of these may be considered “keystone” species, so named because their removal
may result in what conservation biologists refer to as “cascading effects” through the
ecosystem (Terborgh et al. 2003). In this case those effects would include higher
populations of their prey species, which in turn could reduce the populations of the
smaller animals and plants that they feed on. The Cougar, Eastern Wolf, and Black
Bear (Ursus americanus) are examples of top-level carnivores that have disappeared
from highly fragmented landscapes in southern Ontario because forest patches are too
small and too isolated to support them. In short, as species disappear due to habitat
fragmentation, whole ecological communities are affected. This means that vital
interactions for the ecosystem may be lost.
3.1.2 Habitat Patch Shape
Patch size and shape are reciprocal features. All patches have both. As a result, the
influence of one over the other on biodiversity is not always clear or exclusive.
Shape is an issue for two main reasons. The first is in relation to the concept of interior
habitat, which is of importance primarily for forests. Forest interiors tend to be darker,
cooler and damper than areas near the outer edge of a patch. This is a specialized
habitat required by many wildlife species, particularly birds such as thrushes. When
forests dominated the landscape forest interior would have been ubiquitous and these
birds would have been abundant. Now many species are experiencing population
declines, and habitat fragmentation has been implicated as a factor (Terborgh 1989).
More compact patches are likely to have more forest interior when they are above a
minimum size of approximately 4 ha (Figure 3).
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Figure 3. Large, compact patches have more interior than smaller convoluted Patches (Ecological Services for Planning 1995).
There has been growing dissent in the conservation community about the legitimacy of
focusing on forest interior. The criticism is based on studies suggesting that it is the total
amount and configuration of forest cover that determines presence of area-sensitive
birds (e.g. Villard 1998). This interpretation appears to confuse area sensitivity with
forest interior. An area-sensitive species such as Scarlet Tanager (Piranga olivacea)
can breed successfully if the total cover it requires is fragmented but in close proximity.
Other species such as Hooded Warbler (Wilsonia citrina) have been demonstrated to be
area sensitive because of complex social structures, yet remain productive if the habitat
they need is in close proximity (Norris and Stutchbury 2001). Nevertheless, there are
still many species that require the cool moist conditions that would not be found in
smaller woodlots in close proximity, even if in total they make up an equivalent area of
forest cover.
The second reason why shape is important is because of exposure to negative external
influences or “edge effects.” These include higher temperatures, desiccation and storm
damage caused by exposure to sunlight and wind, increased invasion by exotic species,
and higher rates of predation and parasitism. Generally speaking, the more convoluted
or perforated a patch is, the more it is exposed it is to negative edge effects.
Conversely, compact-shaped patches have less exposure. A perfect circle has the
lowest edge-to-area ratio and therefore the least exposure.
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To illustrate the issue of predation as a negative edge effect, in much of southern
Ontario and heavily settled landscapes of northeastern North America there is a
proliferation of habitat generalist species (as opposed to specialists that require specific
habitat types). These freely navigate much of the landscape and readily search forest
patches for food. Some of them, including Raccoon (Procyon lotor), Striped Skunk
(Mephitis mephitis), Opossum (Didelphis virginiana), Red Fox (Vulpes vulpes), and
Coyote (Canis latrans), are “mesopredators” (medium sized) that readily raid bird nests
or prey upon other small animals that are restricted to forest habitat.
The Brown-headed Cowbird (Molothrus ater) is a brood parasite that lays its eggs in the
nests of other birds. The larger and more aggressive cowbird chick then dominates the
nest, resulting in the starvation or expulsion of the bird’s own offspring. Although they
are open country birds, cowbirds will readily penetrate several hundred meters into a
forest patch in search of nests to parasitize. Thanks to habitat fragmentation forest
patches are exposed to higher rates of parasitism from inflated populations of cowbirds,
and large numbers of native songbirds are producing cowbird chicks more than their
own, which contributes to population declines (Brittingham and Temple 1983).
The degree of penetration into a forest patch may vary according to the specific edge
effect. Temple and Cary (1988) predicted that most parasitism occurred within 100 m of
the forest edge and that the area beyond 100 m could therefore be suitable as interior
habitat. This 100 m rule is now commonly applied to define forest interior. Despite the
complexity of the issue, this has been widely applied as a standard simple measure of
forest quality.
3.1.3 Habitat Patch Isolation/Connectivity
Species that have limited mobility or that require very specific habitat types are
particularly vulnerable to habitat fragmentation because they have difficulty moving from
one patch to another. In the first case, a species with limited mobility may not be able to
physically traverse the distance between patches. In the second case, the landscape
between the patches is inhospitable, and therefore creates a barrier to movement. The
more isolated the patches, the less opportunity there is for movement between them.
Spring ephemeral wildflowers are an example of species that can be highly sensitive to
isolation. Not only do some of these require very specific habitat conditions, they also
have extremely limited mobility. Some species such as Mayapple (Podophyllum
peltatum), Trout Lily (Erythronium americanum) and some ferns spread slowly by root
suckering, while others, such as Spring Beauty (Claytonia caroliniana), rely on ants to
disperse their seeds. A study of Dutchman’s Breeches (Dicentra cucullaria) concluded
that this plant could spread only about one hundred yards per millennium (Sauer 1998).
Generally speaking, isolated populations are more prone to extinction. For example, the
population could use up all of the food resources in a habitat patch and have no means
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of moving to another location. Or, a species that requires more than one habitat type to
complete its life cycle, such as an amphibian, may no longer have access to each
habitat type. Of particular concern is the fact that isolated populations, especially if they
are small, have limited genetic diversity. Without recruitment of individuals from outside
populations they may be subject to inbreeding depression and the consequent loss of
fitness. This can ultimately limit persistence because the options for adapting to
environmental change or resisting disease have been diminished. This is a very
significant point in relation to biodiversity conservation because it means that the
presence of a species in one or more habitat patches today does not guarantee that it
will still be there in the future. The population may already be at risk.
The most obvious solution to dealing with the problems associated with patch isolation is
to maintain or restore habitat connectivity. Connectivity has been defined as “the degree
to which the landscape facilitates or impedes movement among resource patches”
(Taylor et al. 1993). Two main types of connectivity are recognized. Structural
connectivity relates to the spatial arrangement of habitats in the landscape. Functional
connectivity is the behavioural response of organisms to that structure (Bennett 1999).
The most widely promoted form of landscape linkage for maintaining connectivity is the
habitat corridor. A corridor can be defined as “a linear landscape element that provides
for movement between habitat patches” (Rosenberg et al. 1997). They may also be
referred to as wildlife movement corridors, biological corridors, and greenways, although
the latter term is often used for something designed as much or more for human
movement as for wildlife (Little 1995). The idea is to provide an opportunity for wildlife to
navigate safely from one habitat patch to another. By doing so additional resources may
be available or there may be an improved opportunity for genetic exchange between
populations, promoting fitness.
In general, the more specialized are the habitat requirements of a species, or the more
sensitive it is to predation, the more it will rely on continuity of the habitat(s) for
movement in the landscape, and therefore would benefit from corridors. Other forms of
structural connectivity may suffice for less specialized or more mobile species. For
example the close proximity of patches can allow for some species to move between
them provided the intervening habitat is not inhospitable and no barriers are in place. A
series of patches in close enough proximity can provide a “stepping stone” function for
some species as they move between larger patches in an otherwise inhospitable
landscape.
3.1.4 The Landscape Matrix
Landscapes can be divided into three spatial elements: patches, corridors, and the
matrix (Forman 1995). Patches and corridors have been discussed above. These are
essentially elements within the matrix, which is the dominant form of the landscape.
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According to Forman and Godron (1986) “the matrix is the most extensive and most
connected landscape element type, and therefore plays the dominant role in the
functioning of the landscape, (i.e. the flows of energy, materials and species).”
In the heavily settled landscape of southern Ontario the matrix is typically composed of
agricultural land or urban land. These dominant land use types have influence on the
patches and corridors of habitat found within them. Some of these influences include
the negative edge effects that originate in the matrix. In this regard, a measure of patch
shape attempts in part to measure exposure to these impacts, while a measure of the
matrix influence would relate to the impacts themselves. An urban matrix, with higher
human populations and associated activities is likely to have more of a negative
influence and provide more barriers to movement than an agricultural matrix.
3.1.5 Habitat Patch Configuration
Patch configuration relates to the pattern in which patches occur within the landscape.
The proximity and direction of large versus small patches of different shapes, habitat
type and quality within the context of varying landscape matrices has a profound
influence on biodiversity and ecological function. All of these patch characteristics,
combined with patch configuration determine the structure and interaction of species
metapopulations and metacommunities.
A metapopulation is the sum total of all the individual populations of a species within the
landscape (Hanski and Simberloff 1997). In a fragmented landscape these individual
populations are likely to be of varying sizes and demographic structure, and may not be
viable on their own. The presence of a species within individual patches may fluctuate
over time through extinction and re-colonization (Levins 1969). In order to maintain
long-term persistence of a species that requires the habitats found in the patches it is
critical to ensure sufficient interaction between the individual subpopulations for normal
behavioural patterns and mating opportunities to occur that will provide enough genetic
diversity to support the entire metapopulation.
A metacommunity is a collection of communities connected by dispersal (Hanski and
Gilpin 1991). In this case, a community is a collection of individuals that directly or
indirectly interact by partitioning the resources of a shared habitat patch (Hubbell 2001,
Holyoak et al. 2005). Metacommunity theory goes a step further than metapopulation
theory by suggesting that species interactions also will be strongly influenced by the
spatial configuration of habitat patches, in addition to the amount of dispersal of
individual species between remaining patches (Holyoak et al. 2005). This means that
the ecological communities themselves will be different from one patch to another, and
therefore that ecological integrity will vary between them. From a conservation
perspective then, the goal would be to maintain enough of the essential community
dynamics among the varying patches to ensure the long-term persistence of each of the
ecological community types that are native to the region.
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The concepts of metapopulations and metacommunities have profound implications for
managing landscapes. For example, it is now apparent that habitats appearing to be
healthy to the untrained eye may in fact have limited ecological integrity. More
significantly, if achieving the goals of ecological health and integrity and sustaining these
over the long term requires maintaining the full complement of biodiversity known to
occur in a given area, then we may not only need to keep most of the remaining habitat,
we will have to strategically add habitat to the landscape. All successional levels of all
vegetation community types must be represented in sufficient quantity and quality to
support all of the native species components of the ecosystems.
3.2 Invasive Species
It is commonly accepted that, next to outright habitat loss, invasive species represent the
greatest threat to global biodiversity (Vitousek et al. 1996). According to the Invasive
Alien Species Strategy for Canada (Government of Canada 2004), invasive species are
“harmful alien organisms whose introduction or spread threatens the environment, the
economy, or society.” Alien species are “species of plants, animals, or microorganisms
introduced by human action outside their natural past or present distribution”
(Government of Canada 2004). In their new environment invasive exotic species
generally lack the natural ecological controls (e.g. predation, herbivory or disease) that
regulate populations of native species.
One insect species in particular is of great concern in the GRCA. The Emerald Ash
Borer (Agrilus planipennis) has spread to numerous parts of southern Ontario and has
recently been found in the GRCA area. This beetle represents a serious threat to ash
trees of any age class. Fortunately ash is a minor component of most woodlands in the
GRCA area, but its loss will nevertheless affect forest ecosystems, especially in moist
areas where it is most abundant, and where it is used as a street tree in urban areas.
Emerald Ash Borer (Agrilus planipennis) / Photo credit: Canadian Food Inspection Agency
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In the GRCA a number of invasive plants are prevalent (species details can be found in
Pridham, 2009). Currently the most threatening is likely Pale Swallowwort, also known
as Dog-strangling Vine (Cynanchum rossicum), which invades woodlands and open
fields. This plant is in the milkweed family, and like other milkweeds the seeds spread
easily through the landscape by wind. Dog-strangling Vine can form dense mats that
can smother or prevent regeneration of other plants. It is currently prevalent on the Oak
Ridges Moraine and can be found in abundance in parts of the Ganaraska Forest.
Pale Swallowwort or Dog-strangling Vine (Cynanchum rossicum)
Garlic Mustard (Allaria petiolata) is an herbaceous plant that invades woodlands. It is
allelopathic, that is, it secretes chemicals into the soil that other plants cannot tolerate.
Garlic Mustard can take over the entire herbaceous layer of upland and riparian forests,
eliminating native wildflowers and preventing tree regeneration.
Garlic Mustard (Allaria petiolata)
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Common Buckthorn (Rhamnus cathartica) is a European shrub that was introduced in
Ontario as a windbreak. In the autumn the black berries are spread across the
landscape by birds. This plant can completely take over the understorey of woodlands,
reducing forest plant biodiversity and making movement difficult.
Common Buckthorn (Rhamnus cathartica)
A recent arrival that is as much of a health concern as an ecological concern is Giant
Hogweed (Heracleum mantegazzianum). This huge herbaceous plant prefers moist
areas and can grow to 5 m in height. Hogweed sap can cause photodermatitis resulting
in severe skin blistering and even blindness if it is accidentally rubbed in the eyes.
Giant Hogweed (Heracleum mantegazzianum)
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Many other species of invasive plants have become well established in southern
Ontario, and with population growth and cross-border movement of goods more are
likely to arrive in the future. Eradication of most species is not feasible, therefore control
measures must be based on available funding and priority areas such as high quality
natural areas or habitats of species at risk.
3.3 Roads
Road ecology is a rapidly expanding science concerning the impacts of roads on
ecosystems. These impacts include habitat fragmentation, creating barriers to wildlife
movement, wildlife mortality, spread of invasive species, noise, artificial lighting, and
introduction of pollutants into the environment (Forman et al. 2003).
Within the context of a terrestrial natural heritage strategy, other than the obvious
impacts of habitat fragmentation described previously, the main concern about roads is
their impact on wildlife populations. For example, some small mammals are reluctant to
cross wide openings created by roads because of exposure to the risk of predation,
especially by hawks. This restricts dispersal of individuals between populations,
potentially reducing genetic diversity. Road kill also has a direct impact on wildlife
populations.
Amphibians and reptiles are vulnerable to road mortality because of their small size and
rate of movement. Turtles are particularly at risk due to their slow speed. Complicating
factors include mass migration of amphibians across roads to reach breeding pools
under ideal weather conditions and the attraction of species such as snakes to the
warmth retained by roads in early morning or evening.
Snapping Turtle (Chelydra serpentina) nesting on Roadside
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The function of a natural heritage system is clearly compromised by the presence of
roads and traffic. The use of mitigation measures such as underpasses or overpasses
(collectively referred to as “ecopassages”) is growing in North America, and an
assessment of roads as barriers to wildlife movement as well as of roadkill hotspots is
recommended as a means of identifying priority areas for ecopassages (Ontario Road
Ecology Group 2010). Beyond mere mitigation, the potential of roads to act as corridors
for some native plant species, or for roadsides to support rare communities such as
prairies, also should be considered.
3.4 Urbanization
The process of urbanization involves an essentially permanent conversion of natural or
agricultural lands to human habitat that is characterized by dense road networks,
housing or industry. Urbanization, particularly in the form of urban sprawl, can have
profound impacts on biodiversity and ecological function that go well beyond habitat loss
(see Johnson and Klemens 2005 for an excellent summary). For example, the human
habitat that comprises urban areas is incompatible to most species that require any
particular type of natural habitat. Instead, a suite of species that are highly tolerant of, or
actually benefit from the urban environment thrive here. Many of these are non-native,
and in total their diversity is far lower than the diversity of native species in natural
ecosystems.
Lawns and gardens are first and foremost designed for the benefit of humans, thus even
when wildlife attraction is the stated goal it is always the species that people wish to
attract because of qualities they find appealing. Species that personal tastes reject are
discouraged. Under these circumstances, real benefits to biodiversity are limited. Many
lawn and garden plants are exotic species, and some, such as Norway Maple (Acer
platanoides), honeysuckles (Lonicera spp.), English Ivy (Hedera helix), and Periwinkle
(Vinca minor), to name a few, are invasive, and have negative impacts as they spread
into nearby natural areas and ravines (Pridham 2009).
Urban areas are concentrated sources of many pollutants. These include atmospheric
pollutants such as carbon dioxide, and low-level ozone resulting from combustion of
fossil fuels, as well as road salt and petroleum products like oils that wash into catch
basins and make their way into streams and rivers. Pesticides used to maintain lawns
and gardens also find their way into water bodies and natural areas and may have
impacts on non-target beneficial species. Other pollutants that effect wildlife include
high levels of noise and artificial night lighting, which is known to affect the behaviour of
many species (Rich and Longcore 2006).
Remaining natural areas in cities are typically under heavy pressure from recreational
uses. For example, walking trails and mountain bike trails commonly penetrate into
once remote areas, resulting in erosion, disturbance to wildlife and introduction of
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invasive plants. Even designated paved trails can result in wildlife mortality. For
example, snakes may be drawn to warm asphalt in the morning, and are inadvertently
killed by cyclists. Common activities of adults in city ravines include collection of
wildflowers, fiddleheads and mushrooms, while children may collect small animals such
as reptiles and amphibians. In addition, pets such as dogs and cats disturb or prey upon
wildlife species living on or near the ground.
3.5 Agriculture
The establishment of farms following European settlement resulted in the loss of vast
areas of habitat in southern Ontario. Today, through clearing, some habitat loss and
fragmentation still occurs, however in south-central and southeastern Ontario it is likely
that this is surpassed by the amount of new habitat created as farmland is abandoned.
It would be erroneous to conclude that agriculture inherently has a net negative impact
on the landscape, although monoculture row crops have very limited wildlife values, and
the use of some pesticides and herbicides may have negative impacts on non-target
wildlife species. On the other hand, some forms of agriculture, such as pasture and
hayfield, provide habitat for wildlife, most notably grassland birds. Hedgerows can
provide a connectivity function for small and large mammals, and open cropland can be
traversed by many animals, including amphibians migrating from forest to wetland and
back. In short, agricultural lands can have both positive and negative impacts on
terrestrial biodiversity, and best management practices can be implemented to help
ensure that the former outweigh the latter.
3.6 Recreational Use
There are numerous recreational uses of terrestrial natural areas and a variety of
impacts associated with them (Wall and Wright 1977). In fact, as much as these
activities may have human health benefits, no form of recreation is completely benign in
relation to biodiversity. Even accessing natural areas on foot can disturb wildlife or
result in the introduction and spread of invasive plants, the seeds of which may be
clinging to boots, clothing, or pet hair. Well used trails can also result in trampling of
vegetation, soil compaction and erosion.
All of the above impacts are multiplied by growing public demand for recreation
opportunities and the increasing use of off road vehicles such as mountain bikes, dirt
bikes and all-terrain vehicles. Few natural areas are now free of at least one of these
activities, and the resulting damage is usually obvious. Both public and private lands are
affected by these uses, although the former tend to suffer from heavier use.
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3.7 Atmospheric Pollution and Climate Change
Natural areas are continuously subjected to various forms of atmospheric pollution. This
includes ground level ozone that contributes to smog. Plants that are sensitive to
ground level ozone develop spotting on the leaves, giving them a brownish appearance.
This restricts the ability of the leaves to undertake photosynthesis and therefore affects
the health and resilience of the plants.
Automobile exhaust and airborne particles of fertilizers can lead to higher than normal
atmospheric levels of nitrogen. Rainfall then deposits some of this nitrogen in natural
areas where it enters the soil. Native plants that are adapted to lower levels of nitrogen
may then become stressed while plants that benefit from high nitrogen levels, including
some invasive plants, thrive and gain a competitive edge. The result is a loss of plant
biodiversity and a decline in ecological health (Sauer 1998).
As if all the above stressors were not enough, global climate change will have
unpredictable and possibly catastrophic impacts on ecosystems. All models predict a
rate of global temperature increase that will occur over a much shorter period than at
any time in the past. Many species, and plants in particular, are adapted to a given
range of temperature and precipitation, thus if conditions surpass this range those
species will become stressed and eventually disappear. Although some models predict
major geographic shifts in forest types, the reality is that the natural dispersal capacity of
many trees and other species will not allow them to shift their ranges fast enough. To
make matters worse, fragmented landscapes already prevent the dispersal of many
species, and therefore will exacerbate the problem. The result may be novel
ecosystems made of those species that tolerate the changes and those which have
recently emigrated from other areas. How well these systems will be able to function
remains to be seen, however there is no doubt they will be less healthy and productive
than systems made up of species that have evolved together over millennia. Obviously
this has implications for production of natural resources such as timber.
4. THE NATURAL HERITAGE SYSTEM CONCEPT
Modern western society is a multi-dimensional system built by and for a single species.
The system consists of nodes of human settlement areas connected by a network of
transportation corridors within a landscape that is often dominated by human activities
such as agriculture. In southern Ontario this system has been imposed upon the
historical landscape such that the original natural systems have disappeared or become
fragmented and isolated. Imagine if we lost connectivity in our society. Our
communities would become isolated. Trade and transport would breakdown. Without
these there would not be enough resources to maintain our towns and cities. In
essence this is what we have done to ecosystems. Natural functions across the
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landscape such as dispersal have been compromised. Isolated wildlife populations in
remaining habitat fragments are disappearing because of inbreeding or insufficient
resources. The health of the system is under threat. To rectify this situation we must re-
build and reconnect natural systems and do so in a manner that can be balanced with,
and support human needs.
Until the mid 1980’s conservationists were using an “islands of green” approach (Hilts et
al. 1986), attempting to have the best-of-the-best represented in protected parks and
reserves. In many cases the lands surrounding such protected areas had been, or later
became converted to human uses, leaving them as isolated islands of natural habitat.
As far back as 1967 the theory of island biogeography was developed to explain the
number of species found on real islands (MacArthur and Wilson 1967). The theory
postulated that the number of species was in part related to the size of the island and its
distance from shore and was a balance between extinction and the immigration and
emigration of species. Smaller, more distant islands were likely to have fewer species
than larger islands in close proximity to the mainland. This is because smaller islands
tend to have fewer resources, and fewer species were likely to reach more distant
islands. The implications of this theory for fragmented landscapes where habitat was
found in patches of various sizes and distances from each other was obvious, and it can
be argued that island biogeography, combined with metapopulation theory and
population genetics, were major factors in the development of conservation biology as a
separate field of science in the late 1980’s.
Although there are many factors to consider, conservation biology theory suggests that
recently isolated populations of species such as those in fragmented landscapes may
have a reduced capacity to survive into the long term. First, they may consume all
available resources in a habitat patch and go extinct. Or they can be easily lost to
disease or disasters such as fire, or the introduction of new predators. A more insidious
threat is that without interaction with other populations for genetic exchange, inbreeding
and a reduction in fitness is likely. With all of the stresses on natural areas in the
present age – over-use, high rates of predation and parasitism, invasive species,
disease, pollution, and climate change – fitness and the ability to adapt have never been
more important.
Habitat connectivity has become a major issue in conservation biology because this is
clearly the approach required to deal with patch isolation and the need for gene flow
(Crooks and Sanjayan 2006). The concept of a protected areas network composed of
large core habitat areas connected by habitat corridors (Figure 4) was first proposed by
Noss (1983), and has since been widely advocated at geographic scales ranging from
watersheds (TRCA 2004), to states and provinces (Noss and Harris 1990, OMNR
2000a), to continents (Noss 1992). In Ontario these networks are frequently referred to
as natural heritage systems, based on use of the term natural heritage in the Provincial
Policy Statement (2005). The Oak Ridges Moraine Conservation Plan (OMMAH 2002)
and the Greenbelt Plan (OMMAH 2005) both define natural heritage systems at a large
landscape scale.
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Figure 4. Protected Areas Network or Natural Heritage System (Asian Development Bank)
5. POLICY RATIONALE FOR A NATURAL HERITAGE SYSTEM APPROACH
5.1 Provincial Policy
The Planning Act authorizes the Province to develop policy on matters of provincial
interest that are affected by land use planning. Section 2.1 of the 2005 Provincial Policy
Statement (PPS) outlines policies related to natural heritage. While most of the specific
policies relate to protecting significant features, Section 2.1.2 states that:
“The diversity and connectivity of natural features in an area, and the long-term
ecological function and biodiversity of natural heritage systems, should be
maintained, restored or, where possible, improved, recognizing linkages between
and among natural heritage features and areas, surface water features and
ground water features.”
Thus the PPS promotes protection of natural heritage systems and ecological function.
It is important to note that in the PPS glossary of terms, the definition of Natural Heritage
System includes “lands with the potential to be restored to a natural state.” This is a
crucial point, because it means that not only does the Province recognize the need to
protect existing features, but areas that have restoration potential to create an improved
natural heritage system as well. This is a key component of the GRCA approach.
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The Ontario Ministry of Natural Resources (OMNR) has proposed a vision statement for
the desired future state of natural heritage systems in southern Ontario. It states that
natural heritage systems “will effectively conserve biodiversity, including composition
structure and function, and support a high quality of life in Southern Ontario” (OMNR
2006). The OMNR has also produced a revised Natural Heritage Reference Manual
(OMNR 2010) that includes an appendix outlining a recommended approach to natural
heritage system planning. To help planning authorities identify Significant Wildlife
Habitat as per the PPS, OMNR also produced the Significant Wildlife Habitat Technical
Guide (OMNR 2000).
5.2 Oak Ridges Moraine and Greenbelt Plans
Among the objectives of the Oak Ridges Moraine Conservation Plan (OMAFRA 2002)
are maintaining and improving ecological and hydrological function and integrity. In part
this is to be accomplished through designating and zoning of the moraine. These zones
include Core and Linkage areas, therefore the natural heritage system concept is being
applied as a planning approach for the moraine. The Greenbelt Plan (OMAFRA 2005)
also refers to a Natural Heritage System of core areas and connecting corridors.
5.3 The Ontario Biodiversity Strategy
Protecting What Sustains Us, Ontario’s Biodiversity Strategy (2005), suggests that “a
broad vision of the landscape is needed to provide a context for biodiversity
conservation,” and further that “biodiversity conservation must be built into all aspects of
land use planning.” The revised Strategy (Ontario Biodiversity Council 2011) includes
“adopt landscape conservation planning and comprehensive land use planning
approaches at all scales” as a key action, and includes as a target “by 2015 natural
heritage systems plans and biodiversity conservation strategies are developed and
implemented at the municipal and landscape levels.”
5.4 Conservation Authorities Act
The Conservation Authorities Act provides the legislation for the creation and function of
Conservation Authorities, and directs them to function in areas related to watershed
planning and management. From the perspective of natural heritage protection, Section
20 of the act allows a Conservation Authority to “establish and undertake, in the area
over which it has jurisdiction, a program designed to further the conservation,
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restoration, development and management of natural resources other than gas, oil, coal
and minerals.”
Section 21 of the Conservation Authorities Act establishes the powers of Conservation
Authorities. In relation to natural heritage these include:
To study and investigate the watershed and to determine a program whereby the
natural resources of the watershed may be conserved, restored, developed and
managed;
To collaborate and enter into agreements with ministries and agencies of
government, municipal councils, and local boards and other organizations
To cause research to be done; and
Generally to do all such acts as are necessary for the due carrying out of any
project.
The work of Conservation Authorities was historically focused on restoration of degraded
environments. Later this shifted more toward water quality and quantity. Within the past
two decades there has been an increasing acknowledgement that these are inseparable
from management of the terrestrial landscape. The amount of forest and wetland cover,
for example, directly affects water quality and quantity, as does the amount of
impervious surface in urban areas. This, combined with recognition that the province
does not have adequate resources to deal with terrestrial issues on a watershed level,
has led many Conservation Authorities to develop terrestrial natural heritage programs.
By protecting and improving a natural heritage systems conservation authorities are
returning to their original mandate.
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6. THE GANARASKA REGION CONSERVATION AUTHORITY NATURAL HERITAGE APPROACH
Choosing an Approach for Defining Natural Heritage Systems
The Province recommends establishment of “high-level direction” through stakeholder
involvement as critical to a “Coordinated, Integrated and Comprehensive Approach for
defining natural heritage systems (OMNR 2010). To help ensure acceptance of the final
product this process identifies key stakeholders (e.g. municipalities, conservation
authorities, government departments such as Ministry of Municipal Affairs and Housing,
First Nations, the aggregate industry, and agricultural, landowner and environmental
groups), and engages these at the beginning and at key stages in development of the
system. This includes a visioning exercise and agreement on the methodology and
criteria used to define the system.
Despite the merits of this approach, there are risks involved. For example, excluding
natural areas from the natural heritage system from the beginning because they cannot be
protected means that the values that these areas currently have may not be accounted for.
A more serious risk is that the resulting natural heritage system may be compromised if
non-environmental interests are given equal weight at the negotiating table with the
environmental interests, and especially if non-environmental criteria are given equal
weight in the model used to define the system. This would not reflect an “environment
first” approach which is often called for by the public in planning processes, and which
would provide the foundation for sustainability. The economy and human interests are
important. However, these depend on the environment (ecological goods and services),
while the reverse is not the case.
An alternative approach is to use an existing methodology for defining natural heritage
systems developed by experts in conservation biology and landscape ecology, and then
to bring in the stakeholders to learn about the issues and approach, and to review the
results as presented in scenarios. Alterations and deletions to the system might then
occur with the knowledge that they may be compromising a target system that was
defined to maintain biodiversity and ecological health. Through a process of give and
take, a solution might then be negotiated that reduces the target system in some areas but
makes up for these losses in other areas, or that chooses the most acceptable scenario.
The GRCA has adopted (and slightly modified) the criteria and GIS model developed by
the Toronto and Region Conservation Authority (TRCA 2004), which has already been
peer reviewed and implemented for both urban and rural landscapes in the Greater
Toronto Area. Using a proven approach helps ensure consistency between one
jurisdiction and another and is ultimately more defensible than creating a new approach
based entirely on local interests or concerns.
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6.1. Overview of Approach
The natural heritage system approach used by the GRCA is a slightly modified version
of the approach developed by the Toronto and Region Conservation Authority (TRCA
2004). The approach considers three levels: landscape, vegetation communities, and
species. These levels roughly correspond to those considered in the concept of
biodiversity (i.e. ecosystem diversity, species diversity, and genetic diversity). Some
conservation biologists also consider landscape pattern as a level of biodiversity (Noss
and Cooperrider 1994). Measuring and monitoring genetic diversity is beyond the
capacity of the analysis, however by including landscape structure and habitat
distribution the physical factors that affect population biology and genetic diversity will be
addressed indirectly. Each of these levels and their relevance is discussed briefly
below.
6.2 Landscape Level
The emerging science of landscape ecology considers the impact of landscape pattern
and structure on ecological function. All landscapes can be divided into three main
components: patches, corridors, and the matrix (Forman 1995). The matrix is the
dominant landscape feature such as forest or agriculture. Within the matrix are patches
of other natural habitat or land use types such as blocks of forest within an agricultural
landscape, or small towns in a forested landscape. Corridors are linear features that
connect patches, for example valley lands connecting woodlots, or roads connecting
towns. What constitutes a landscape is relative, and it would likely be different for an
insect and for a large mammal. This demonstrates the importance of scale when
evaluating landscapes. For the GRCA the most relevant scales are the entire land base
over which they have jurisdiction, as well as the individual watersheds of which the
jurisdiction is comprised. No one scale should be addressed without some consideration
for how patterns there relate to those at higher and lower scales. Furthermore, unlike
aquatic species, terrestrial species are not bound to an individual watershed. Therefore
the role of adjacent watersheds or jurisdictions in supporting populations must be
considered.
The GRCA approach evaluates the terrestrial landscape using Geographic Information
Systems (GIS) software to measure and rank habitat patch and landscape
characteristics. The method includes a vector analysis of existing landscape conditions
and applies a raster based model to define potential improvements (see Appendix 1).
The vector analysis uses polygons to represent patches and evaluates the
characteristics of these, while the raster analysis divides the landscape into pixels, and
assigns values to each of these based on a number of ecological criteria.
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Landscape indicators include changes in forest, wetland and urban cover, as well as
mean habitat patch size and shape. Potential measures for future consideration include
a mean connectivity value and a road density measure.
6.3 Vegetation Community Level
The biotic components of ecosystems interact in what can be termed communities.
These are made up of species that are adapted to certain physical and climatic
conditions. A description of the vegetation found in these communities is the most
obvious way to classify them. The GRCA makes use of the Ecological Land
Classification System (ELC) for Southern Ontario (Lee et al. 1998). This system is
hierarchical, defining vegetation communities at a series of levels ranging from those
which can be identified remotely using air photo interpretation, to levels that require on-
the-ground assessment of soils, drainage, and individual plant species. As an example,
the code FOD represents deciduous forest at the Community Series level, FOD1
represents dry-fresh oak deciduous forest at the Ecosite level, and FOD1-1 represents
fresh red oak deciduous forest type at the most detailed Vegetation Type level.
The GRCA uses the Community Series level as the principal means of mapping and
tracking the status of vegetation communities. This level is mapped remotely with GIS
by digitizing polygons around discernible features on the landscape using colour
orthographically rectified aerial photographs (orthos) as the base. In addition to the ELC
community types, the GRCA uses a number of human land use classifications
commonly used by other conservation authorities such as intensive and non-intensive
agriculture, aggregate pit, rural development, manicured open space, urban, etc.
Together these provide full coverage of all vegetation community types and land uses on
the landscape. Figure 5 shows a sample area of the ELC mapping.
For individual site assessments the GRCA uses the most detailed vegetation type level
of the ELC. This level is also important for identifying rare community types, and the
Natural Heritage Information Centre (NHIC) has defined these for Ontario based on the
number of occurrences of each vegetation type.
Vegetation community indicators include total cover of rare community types such as
tallgrass prairie, and the relative representation of all vegetation community types.
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Figure 5. Sample of ELC Community Series Mapping
6.4 Species Level
Species are the most widely recognized component of biodiversity. The large number of
plant and animal species in southern Ontario makes it necessary to focus on select
groups for evaluation and conservation. These should include species at risk,
uncommon species, and indicator species.
Species at Risk (SAR) include those that have been officially designated as
Endangered, Threatened, or Special Concern either federally by the Committee on the
Status of Endangered Wildlife in Canada (COSEWIC) or provincially through the
Committee on the Status of Species at Risk in Ontario (COSSARO). Technically, SAR
are the responsibility of the federal government on federal lands and waterways, and the
provincial government everywhere else. Therefore the GRCA merely reports such
species to the NHIC when they are encountered, and incorporates information on
element occurrences in watershed planning and plan review.
Uncommon species include those that are naturally rare because they are at the top of
the food chain or have highly specialized habitat requirements, as well as those species
that are particularly sensitive to human activities and land use. Top-level carnivores
such as Eastern Wolf and Cougar were among the first species to disappear from
southern Ontario as the once vast forests were converted to agriculture. At present it is
questionable whether or not there is either sufficient habitat or the social will to allow
these species to return.
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Highly specialized species are those that rely on a single food source or very specific
and rare habitat conditions. Some prairie, alvar, or bog plants would be examples of
these. Species that are sensitive to human activities include amphibians such as
salamanders that require very specific upland and breeding habitats and are susceptible
to road kill. Also in this category would be reptiles such as turtles and snakes. Birds
that are area sensitive or forest interior species also fit this category because they
require larger blocks of habitat which themselves are less common in heavily settled
landscapes.
The GRCA approach considers uncommon and sensitive species indirectly through
advocating a target natural heritage system to increase species representation and
promote population viability, as well as by tracking vegetation communities that some of
these species are specifically adapted to. A more direct approach will involve the
development of a local species of concern list based on abundance, distribution, and
sensitivities. This list would then help to inform the review process for land use planning.
Because it is impossible to track the population status of all species, or even all sensitive
species, it is necessary to use a proxy approach and select a series of indicator species.
There are many considerations in doing so. Species roles in ecosystems vary from
habitat generalists that move freely through most habitats and land use types, to habitat
specialists that require a very specific habitat type or conditions that are found in few
localities. The difference between these can be viewed as a gradient from common to
rare. In this case the presence of rare species would indicate that the special conditions
they are associated with are present, and therefore that those species and components
of biodiversity are represented. Rare species in this context are naturally rare, and
would make better indicators than species that have become rare due to human
activities.
Other species may not be as specific in relation to their habitats yet be sensitive to the
quality of the habitat. For example, forest interior or area-sensitive birds may not be as
sensitive to the type of forest as to the size of the woodland or the amount of forest
cover in a given area. The presence of some, such as certain amphibian species, may
be dependent on the proximity of more than one type of required habitat, in this case
upland forest and wetland.
Indicator species are not generally used to summarize the status of species so much as
they are to indicate the quality of habitat or the condition of the landscape. The GRCA
uses birds and frogs as indicators of forest and wetland quality and configuration. These
groups were selected not only because their habitat requirements are well known and
often specialized, but because they vocalize and are therefore easily detectible. The
GRCA has adapted the Marsh Monitoring and Forest Bird Monitoring protocols to
roadside point counts adjacent to a diversity of suitable wetland habitats and forest patch
configurations. The monitoring approach used is surveillance. Species are tracked over
time, but not in relation to a single parameter or anticipated outcome (Goldsmith 1991).
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7. SUMMARY OF EXISTING NATURAL HERITAGE CONDITIONS
7.1 LANDSCAPE LEVEL
7.1.1 Total Cover of Major Habitat Types
This section summarizes the total amount of major habitat types, including forest,
wetland, meadow and beach/bluff. It does not consider the amount of cover or the
condition of the different vegetation communities that these major habitat types can be
broken down into (e.g. deciduous, coniferous or mixed forest as opposed to simply forest
cover). That discussion occurs in the following section. The purpose of this section is
to look at landscape level conditions only. Map 1 shows these major habitat types as
well as land use, while Figure 6 summarizes the relative abundance of these.
Figure 6. Pie Chart summarizing total cover of major vegetation types and land uses
Major Habitat Hectares Percentage
Aggregates 377.99 0.41%
Beach / Bluff 84.94 0.09%
Forest (including swamp) 28,415.75 30.58%
Intensive Agriculture 34,147.78 36.74%
Meadow 7,654.90 8.24%
Non-Intensive Agriculture 6,907.00 7.43%
Open Water 3,642.69 3.92%
Railway 151.41 0.16%
Road 1,946.48 2.09%
Rural Development 3,999.75 4.30%
Urban Area 4,590.95 4.94%
Wetland (not including swamp)
1,014.35 1.09%
Total 92,934.00 100.00%
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7.1.2 Forest
Based on the GRCA’s Ecological Land Classification System (ELC) mapping the total
amount of forest cover in the GRCA jurisdiction is 30.6 percent of the land base. This
includes natural forest, plantation forest, and forest swamp. The amount corresponds
closely to the 30 percent forest cover figure suggested as a minimum target for the lower
Great Lakes and Mixed Woods Plains area of southern Ontario’s settled landscape
(Environment Canada 2004), a figure that was subsequently selected as a target by
numerous municipalities and conservation authorities. However, this should not imply
that the landscape has sufficient forest cover, let alone that we can afford to lose some.
Based on more recent science the revised How Much Habitat is Enough? guidelines
(Environment Canada 2013), in addition to a 30 percent minimum (which is not referred
to as a high risk approach), recommend forest cover targets of 40 percent and 50
percent as medium and low risk targets for maintaining forest species richness and
healthy aquatic ecosystems.
The majority of the forest cover is found in the upper reaches of the watersheds, and
particularly on the Oak Ridge Moraine. This is beneficial in relation to groundwater
recharge and the maintenance of stream flow because it is known that forests absorb
water and release it gradually (Buttle 1995). The large forest blocks on the Oak Ridges
Moraine also support many area sensitive species. Nevertheless, this skewed
distribution of forest cover also suggests that other portions of the watersheds are less
likely to support the full suite of forest species, and therefore have less ecological
integrity. As human land use intensifies, natural cover diminishes, and at some point a
threshold is crossed where the integrity of natural systems cannot be maintained.
So long as the natural features that once dominated the landscape are fragmented there
is room for improvement through increasing natural cover. Quite simply, more natural
cover translates into better ecological health. Obviously this must be done in balance
with human demands on the landscape. The target natural heritage system scenarios
suggest where the best options may be for increasing forest cover on the landscape to
meet terrestrial biodiversity goals as applied through the analysis criteria.
7.1.3 Wetlands
Wetlands can be divided into four main categories: marsh, swamp, bog, and fen. The
ELC also defines shallow water wetlands, which are those areas dominated by floating
or submerged aquatic plants. Bogs and fens are rare community types in southern
Ontario south of the Canadian Shield. Within the GRCA some bog features have been
recorded in a small portion of the Newtonville Bog Provincially Significant Wetland, and
some mineral fen features have a very limited representation on the Bond Head Bluffs,
which are designated as an Area of Natural and Scientific Interest (ANSI). The rarity of
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these ecosystems, combined with the difficulty in replicating them, makes them high
priorities for protection.
The ELC defines two main marsh types: meadow marsh and shallow marsh (Lee et al.
1998). Meadow marshes are typically wet meadows dominated by water tolerant
grasses or sedges. They are often found in floodplains, and include areas that were
previously flooded as a result of beaver dams. Because they are often maintained by
dynamic conditions the total cover of these ecosystems can fluctuate dramatically.
Based on ELC mapping, the GRCA jurisdiction currently supports 301 ha of meadow
marsh. However, this is probably an underestimate because these wetlands can be very
difficult to discern from meadows when interpreting air photos.
Shallow marshes are typically areas of standing water or shorelines dominated by
emergent vegetation such as cattails. They include the major coastal wetlands of Lake
Ontario that are found at the mouths of rivers and streams, as well as shoreline areas of
inland lakes and ponds. Currently 265.9 ha of shallow marsh are found in the GRCA
jurisdiction.
Forest swamps and thicket swamps are the two main swamp categories. Swamps are
areas dominated by woody vegetation that are seasonally or permanently inundated by
water. Forest swamps are tree-dominated while thicket swamps are shrub-dominated.
According to the ELC mapping there are 5,020 ha of forest swamp in the GRCA
jurisdiction. However, of all the ELC community types, forest swamps are the most
difficult to identify through air photo interpretation, therefore the mapping of these
features invariably has a degree of inaccuracy. Thicket swamps can also be difficult to
discern with air photos, particularly if dominated by willows, the colour of which does not
stand out as much as that of alder or dogwood swamps. The current known cover of
thicket swamps is 251 ha.
The total cover of all wetland types in the GRCA jurisdiction, including forest swamp, is
6,484.6 ha, which represents 6.9 percent of the total area. The How Much Habitat is
Enough? guidelines recommend 10 percent wetland cover for each major watershed
(Environment Canada 2013). With respect to wetlands, the historical cover varied widely
from one region to another according to soils and climate. There is an alternative federal
guideline of 40 percent of the original wetland coverage in a watershed, however the
historical amount in the GRCA area is unknown, so this is not helpful here. Some areas
would have originally supported much less than 10 percent, therefore having less than
this does not necessarily imply poor health.
Target setting for wetlands should begin with protection of what currently exists
combined with any available knowledge of historical conditions. According to a study by
Ducks Unlimited (2010), pre-settlement wetland cover in the Regional Municipality of
Durham would have been 12.6 percent, and in the County of Northumberland it would
have been 12.9 percent. As of 2002 that wetland cover had declined to 7.8 percent and
7.4 percent respectively. Since the dominant historical wetland type would have been
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forest swamp, where losses occurred, this is probably the type that was most affected.
Therefore if restoration of wetlands is a goal, forest swamp should be a priority.
Deciduous Forest Swamp
7.1.4 Meadow/Grassland
The total amount of open meadow and early successional habitat within the GRCA area
was calculated at 8.2 percent. This includes a small amount of tallgrass prairie, which
will be discussed in greater detail in the vegetation communities section of this report.
There is no general guideline for how much of these open grassland and successional
habitats should exist because for the most part they are anthropogenic rather than
natural features. Typically they result from conversion of forest to agriculture, with
periods of allowing fields to recover by going fallow, or permanent abandonment that
allows them to gradually recover through stages of ecological succession (i.e. becoming
shrubland and eventually forest). As a result, there are varying amounts of each
successional stage from year to year. In future there may be guidelines for these
habitats associated with their ability to support grassland and shrubland bird species at
risk.
7.1.5 Beach and Bluff
Beach and bluff habitats together cover only 84.9 ha, making up 0.09 percent of the
GRCA jurisdiction. These vegetation communities are naturally rare because the
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physical conditions and the plants adapted to them have a restricted geographic range.
With the exception of the developed harbours of Newcastle, Port Hope and Cobourg, the
outright loss of these communities to waterfront development has been minor. However,
as will be discussed in the section on vegetation communities, the quality of these
habitats is for the most part degraded. Thus, although it is unlikely that the total area of
beach and bluff can be increased, there is room for rehabilitation of what remains.
Bond Head Bluffs
7.1.6 Habitat Patch Conditions
The following is a discussion of the inherent characteristics of habitat patches and the
landscape context of them as measured in the GIS landscape vector analysis (See
Appendix 1). The results for existing conditions represent the baseline upon which to
measure changes against the target conditions defined by the GIS raster modeling.
7.1.7 Patch Size
Patch size considers forest, wetland and beach/bluff habitats combined, but does not
include meadow habitats, which in the modeling are considered areas of potential forest.
The patch size results for existing conditions are illustrated on Map 2.
The mean habitat patch size in the GRCA jurisdiction is 5.7 ha. The smallest patches
are under one half hectare, and tend to be in the more heavily settled parts of the
landscape such as Cobourg, Port Hope and Newcastle. As a result there is a general
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gradient of small to large patches as one moves from Lake Ontario to the Oak Ridges
Moraine.
It is no surprise that the largest habitat patches are in the headwater areas on the Oak
Ridges Moraine and include the Ganaraska Forest and the Northumberland County
Forest. These represent the largest patches of forest in Ontario southwest of the
Canadian Shield, hence their value goes beyond the local scale. The largest single
patch is the Ganaraska West Forest at 2,566 ha.
Many large patches are also found through the central portion of the GRCA jurisdiction,
through the branches of the Ganaraska River as well as in the headwater areas of some
of the smaller streams, such as Graham Creek, Gages Creek and some of the smaller
streams draining into Lake Ontario. In short, not only is there good representation of
larger patches, but fairly good distribution as well. Overall the average size of patches is
considerably larger than those found in the more heavily settled landscape of
southwestern Ontario and the Greater Toronto Area (TRCA 2004), yet smaller than
areas further north.
7.1.8 Patch Shape
A large proportion of the habitat patches in the GRCA jurisdiction scored in a moderately
low range for shape (Map 3), although none are in the lowest. This is because so much
of the remaining natural cover is found in valley and stream corridors and therefore
consists of long, narrow and convoluted patches with a high perimeter-to-area ratio.
Patches bordered by roads tend to have better shape scores because most roads are
based on a grid network which results in compact square and rectangle shapes.
The relatively poor shape scores and high perimeter-to-area ratio suggest that negative
edge effects represent a conservation concern in the GRCA watersheds. Fortunately
the surrounding matrix is largely rural, with fewer actual negative influences than
typically would occur in an urban context. Nevertheless there is clearly room for
improvement in patch shape.
7.1.9 Matrix Influence
The largely rural and natural matrix results in overall relatively high patch scores for
matrix influence (Map 4). As would be expected the lowest scores are natural areas that
fall within urban areas such as Cobourg and Port Hope. These and patches in the
Newcastle area would likely have even lower scores were it not for the fact that the
measure considers open water to be a positive, natural matrix influence, and therefore
the presence of Lake Ontario within two kilometers has boosted the patch scores. The
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highest values tend to be on the Oak Ridges Moraine, where the matrix has more
natural and less urban or residential land use.
7.1.10 Total Habitat Patch Score
Adding the values for size shape and matrix influence provides a total score for each
habitat patch (Map 5). While recognizing that there is some overlap between these
measures and that they are not necessarily equal in value, the total score is
nevertheless useful to visualize the relative condition of habitat patches based on their
characteristics and configuration in the landscape. The map shows that patches that are
larger and more compact in shape, as well as have more natural cover in the
surrounding landscape tend to score higher than smaller or more convoluted patches
near urban areas.
7.2 VEGETATION COMMUNITIES LEVEL
Section 7.1 summarized the amount of major habitat types in the GRCA jurisdiction.
Here is summarized the relative amount and condition of vegetation communities based
on the Community Series level of the ELC. The results are reported on for existing
conditions only since it is beyond the scope of this report to determine potential
conditions for each type. Map 6 shows the ELC and land use mapping for the GRCA
jurisdiction, while Figure 7 (pie chart) summarizes the relative abundance of all ELC
vegetation Community Series types.
7.2.1 Forests (ELC codes FOM, FOD, FOC, SWM, SWD, SWC, CUP, CUW)
According to the ELC mapping, of the 27,965.7 ha of mapped forest in the GRCA
jurisdiction, 3,235.4 ha are deciduous forest, 3,403.3 ha are coniferous forest, and
12,145.6 ha are mixed forest. The total also includes 5,020 ha of forest swamp, 3,682.6
ha of cultural plantation, and 478.7 ha of cultural woodland. There are no cover
standards or guidelines for each forest type. Other than plantations, the different types
tend to be found according to the soil, slope, aspect (direction), elevation and moisture
conditions to which they are best adapted. Therefore the relative abundance of each
type naturally changes from one part of the landscape to another.
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Figure 7. Relative abundance of community series level vegetation types in the Ganaraska watershed
KEY TO ELC COMMUNITY SERIES CODES
BBO – Open Beach/Bar BBS – Shrub Beach/Bar BBT – Treed Beach/Bar BLO – Open Bluff BLS – Shrub Bluff BLT – Treed Bluff CUM – Cultural Meadow CUP – Cultural Plantation CUS – Cultural Savanna
CUW – Cultural Woodland FEO – Open Fen FOC – Coniferous Forest FOD – Deciduous Forest FOM – Mixed Forest MAM – Meadow Marsh MAS – Shallow Marsh OAO – Open Aquatic SAF – Floating-leaved Shallow Aquatic
SAS – Submerged Shallow Aquatic SBO – Open Sand Barren SBS – Shrub Sand Barren SWC – Coniferous Swamp SWD – Deciduous Swamp SWM – Mixed Swamp SWT – Thicket Swamp TPO – Open Tallgrass Prairie TPS – Tallgrass Savanna
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Condition and age are important considerations in relation to forest biodiversity and
ecological health. Managed forests and those used for recreation may show more signs
of stress than those left untouched, depending on the intensity of use. For example,
forests with active trails may contain more invasive plants than those that humans rarely
enter because many of these plants are spread on boots or tires. Based on fieldwork it
is known that there is a great range of quality in forests within the GRCA. However, due
to issues of access, land ownership, and financial constraints it is impractical to record
and monitor the quality of most woodlands. Nevertheless, indicator species such as
birds can act as a proxy for forest quality and health if remote surveys of birdsong are
undertaken from public roads adjacent to forests.
An important issue related to forest quality is old growth. According to Ontario’s Old
Growth Policy Act (1994) “Old growth ecosystems are characterized by the presence of
old trees and their associated plants, animals and ecological processes. They show little
or no evidence of human disturbance.” Old growth forests are particularly valuable for
biodiversity. For example, they tend to have intact soils containing most of the
microorganisms, fungi and the decomposer community that is essential to a healthy
functioning ecosystem. Furthermore, as trees mature and die they provide food for
many insects and shelter for birds and mammals, particularly those that are cavity
nesters such as woodpeckers and flying squirrels. Fallen logs in turn provide vital
habitat and cover for small mammals, reptiles, and amphibians such as salamanders
(Henry and Quinby 2010).
A well-known old growth forest just outside of the GRCA jurisdiction is found at Peter’s
Woods Provincial Nature Reserve. Other individual stands of old growth trees can be
found in various locations. These should be mapped, protected where possible, and
their condition and biodiversity monitored. In addition forests that are potential old
growth, that is are maturing but do not yet meet the definitions, should also be identified,
mapped and tracked.
7.2.2 Wetlands (ELC codes SWM, SWD, SWC, SWT, MAM, MAS, FEO, SAS, SAM,SAF)
Figure 7 shows the relative abundance of wetland types according to ELC mapping, but
does not include the small area that has some bog-like conditions in the Newtonville Bog
or the very small fen features found on coastal bluffs, which are too small to map at this
scale.
At a total of 5,020 ha, forest swamp is by far the most abundant wetland type in the
GRCA watersheds. This figure could change based on future information because of
the difficulty in determining the boundaries of swamps through air photo interpretation.
Given that this part of southern Ontario was predominantly forested prior to settlement,
this amount may mirror historical relative abundance conditions for the types of
wetlands, although wetland loss figures as discussed in Section 7.1 do not take into
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consideration the various types. Thicket swamps cover 251 ha, and likewise there is no
good source of information on the historical cover of this particular wetland type.
Vernal pools are components of many forest swamps. The value of these for the life
cycles of many species, particularly amphibians, is receiving increased attention within
the conservation community (Colburn 2005). Unfortunately, mapping of these important
ecosystems is inaccurate because it is often difficult to see them under the canopy when
looking at air photos. These should be mapped as encountered during field work and an
effort made to find ways of mapping them across the landscape. This may include a
landowner outreach program as part of a vernal pool conservation program.
Vernal Pool
Marshland, including meadow marsh (443.6 ha) and shallow marsh (265.9 ha), is the
next most abundant wetland type. The most important of these are the extensive
marshes on Rice Lake and the coastal marshes of Lake Ontario. Although data was
collected during the original evaluation of the Rice Lake wetlands, an effort should be
made to determine the current condition of these significant areas, and whether or not
they currently support species at risk.
Through the Durham Coastal Wetland Monitoring Project there is a better understanding
of the current conditions of the major Lake Ontario marshes in the Municipality of
Clarington. These wetlands are under stress through fluctuating water level changes,
water pollution, and recreational pressures. A recent status report provided a “fair”
grade to both the Wilmot Creek marsh and the Port of Newcastle marshes for the
amphibians and birds, which are the terrestrial quality indicators (Environment Canada
2010). The status of coastal wetlands in the Municipality of Port Hope and Township of
Hamilton has yet to be assessed.
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Durham Coastal Wetland Monitoring, Wilmot Creek Marsh
7.2.3 Meadow/Grassland (ELC codes CUM, CUS, CUT, TPO, TPS, SBO)
The meadows and early successional vegetation types are for the most part areas that
are in various stages of conversion of the land back to forest. Their relative abundance
and condition is of concern primarily in relation to their provision of habitat for species
that depend on them, including those species of grassland and shrubland birds that are
experiencing population declines. Although there is no “natural” amount to base a target
on, the total cover and distribution of these vegetation communities should be tracked to
ensure that there is adequate representation in relation to conservation of these species.
Tallgrass prairie and savanna are rare native grassland habitats that were originally
maintained by fires. Unlike old fields or meadows, which are typically found in moist
loamy soils, prairies and the plant species associated with them are adapted to dry
sandy soils.
From surveyor’s records and the accounts of pioneers such as Catharine Parr Traill it is
known that much of the Rice Lake Plains on the eastern portion of the Oak Ridges
Moraine was historically covered with tallgrass prairie and savanna (Catling et al. 1992).
The actual total cover amount would have varied from year to year based on weather
and fire patterns, therefore it may never be possible to set firm cover targets. However,
there is no doubt that what remains of tallgrass communities throughout their historical
range is a very small fraction of what would have been hear prior to European
settlement. An estimate of 3 percent remaining of the original cover has been used
(Roger 1997). As a result these ecosystems are a very high priority for protection and
restoration.
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Tallgrass prairie and savanna are difficult to discern from open meadow when
undertaking air photo interpretation. Therefore mapping and cover values for these
communities is based on the tallgrass and “sand barren” communities that have been
mapped by the Ontario Ministry of Natural Resources (Map 20). According to this
mapping there are 466.6 ha of tallgrass in the GRCA jurisdiction, which represents a
mere 0.05 percent of the total area. The identification of opportunities to increase cover
of these communities is a high priority.
Tallgrass Prairie, Ganaraska Forest
7.2.4 Beach and Bluff (ELC codes BBO, BBS, BBT, SDO, SDS, SDT, BLO, BLS, BLT)
Beach and bluff communities are dynamic ecosystems that are formed by the movement
of water. As such, the vegetation associated with them may shift according to water
level fluctuations and wave action. Plants in these ecosystems must also be tolerant of
extreme temperatures and wind.
Currently only 27.2 ha of beach and 57.7 ha of bluff are found in the GRCA jurisdiction.
On Lake Ontario, natural beach vegetation communities have become rare as a result of
changing water levels and human activities such as shoreline development. The latter
include hardening of shorelines for erosion control, clearing areas for swimming and
sunbathing, trampling, and use of off-road vehicles. These beaches are also often
subjected to accumulation of garbage that washes ashore. Based on GRCA surveys of
the Lake Ontario coast in The Municipalities of Clarington and Port Hope, it can be
stated that native beach communities survive in only a few locations. At the Wilmot
Creek mouth these have been heavily trampled. A very small, degraded remnant can be
found in front of the water treatment plant at the mouth of Graham Creek. Both of these
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locations are in need of rehabilitation. Surprisingly, the highest quality site appears to be
the west beach at the Port Hope harbour, immediately in front of the Cameco
Corporation facility. This beach still supports many Sea Rocket (Cakile edentula) plants,
a provincially rare species, as well as good representation of other native beach plants
such as Seaside Spurge (Chamaesyce polygonifolia), Beach Clotbur (Xanthium
echinatum), Silverweed (Potentilla answerina), and others. The rarity and quality of this
site suggests that it is a priority area for protection, and should be considered as
Significant Wildlife Habitat.
In a few areas raised dune habitat can be found beyond the water disturbance zone
behind beaches. Unlike high sand dunes such as those found in Sandbanks Provincial
Park, these areas are low in stature, generally only about 20 to 30 centimetres higher
than the beach. Typical vegetation communities on these dunes include Canada Wild
Rye (Elymus canadensis), Beach Wormwood (Artemesia caudata), Spreading Dogbane
(Apocynum androsaemifolium), Sandbar Willow (Salix exigua), and Balsam Poplar
(Populus balsamifera).
Beach and dune vegetation communities, Port Hope
Bluffs are found in numerous places along the Lake Ontario shoreline in the GRCA
jurisdiction. These range from low bluffs of approximately 2 metres in height, to the
extensive Bond Head Bluffs, which are up to 46 metres in height and extend for 5.5
kilometeres (Brownell 1993). The Bond Head Bluffs have been designated a provincially
significant Life Science Area of Natural and Scientific Interest (ANSI) and regionally
significant Earth Science ANSI by the province. Treed and shrub bluff vegetation
communities can be found here, however the most interesting sites are the seepage
areas which support rare hanging fen communities. These contain such locally rare
plant species as Fringed Gentian (Gentianopis crinita), Indian Paintbrush (Castilleja
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coccinea), and Showy Lady’s Slipper (Cypripedium reginae). The hanging fens are
among the most significant vegetation community types in the region.
Rare hanging fen community on Bond Head Bluffs
7.3 SPECIES LEVEL
The high diversity of birds and the many habitat specialists among them suggest that
they can be used as indicators of different environmental conditions. A useful bird
indicator would require specific forest conditions and not be at the edge of its range
(where presence may naturally be sporadic). As with all indicator species however, it
must be kept in mind that the mere presence of a sensitive species does not always
imply a healthy environment. For example it may be possible that an individual singing
male recorded at the site has not found a mate. Or conditions in a small area may be
suitable for a nesting pair, but predation, high rates of parasitism, disturbance, or an
insufficient amount of habitat to support complex behaviour patterns result in nest failure.
Therefore the continued presence of more than one pair over subsequent years is a
better indicator of quality habitat. Long-term monitoring efforts are required to accurately
determine trends.
So far GRCA surveys have focused on forest birds as indicators of forest conditions. In
future, given the capacity to do so, it would be worthwhile to also survey for wetland
birds to supplement the amphibian indicators, as well as grassland birds, many of which
are experiencing steep population declines.
The diversity of bird species and their habitats means that a host of species may be
available for use as indicators of almost any habitat conditions we wish to measure. For
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the purpose of this report the focus is on forest interior birds because these are by
definition area sensitive, and they require specific habitat conditions. Their presence as
breeders should therefore indicate something about forest patch size and quality. For
consistency two of the more common and widely distributed interior species were
chosen. The Veery (Catharus fuscescens) is a thrush, and the Ovenbird (Seiurus
aurocapillus) is a warbler. Both species are ground nesters and therefore are also
potentially more sensitive to disturbance or predation.
Veery (Catharus fuscescens) Source: Cephas. Wikimedia Commons
Map 7 shows the distribution of Veery and Ovenbird according to GRCA roadside and
Forest Bird Monitoring surveys undertaken between 2003 and 2010. Both species are
widely and relatively evenly distributed in the GRCA jurisdiction, reflecting a
corresponding pattern of forest cover. Thus it would appear that the overall quantity of
forest cover and forest interior habitat, as well as the size, quality and distribution of
patches is generally good, with the exception of urbanized areas.
Ovenbird (Seiurus aurocapilla) Source: Dick Daniels (http://carolinabirds.org) Wikimedia Commons
Before becoming complacent, however, it is important to point out that there are other
forest birds that have a higher area sensitivity than Veery and Ovenbird. For example,
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the Cerulean Warbler (Dendroica cerulea) is known to require very large forest blocks for
breeding, and this species was detected only once during the surveys, in the Ganaraska
Forest. Other forest interior or area sensitive species, were they to be mapped, would
show a less even distribution than these two indicators.
Frogs are used by the GRCA as indicators of wetland status. In particular, species were
selected that appear to require very specific conditions and/or have declining
populations regionally. Wood Frog (Rana sylvatica) and to a lesser extent Gray Treefrog
(Hyla versicolor) require wetland and woodland in close proximity, with the former
frequently breeding in vernal forest pools and forest swamps (although both will breed in
open water wetlands at the edge of, or in close proximity to forest). As a result large
numbers of these species suggest good connectivity between forest and wetland. Wood
Frogs are also sensitive to acidification in breeding pools as well as urbanization (Gibbs
et al. 2007). Amphibian Road Call Count (ARCC) data for Ontario show a decline in
wood frog populations, although no trend is noted with Marsh Monitoring Program
(MMP) and Backyard Frog Survey (BFS) program counts (Badzinski et al. 2008).
Wood Frog (Rana sylvatica)
Western Chorus Frogs (Pseudacris triseriata) have a preference for thicket swamps and
were used as indicators for this wetland type. Both the MMP and BFS counts for Ontario
indicate declining trends for this species, and a general decline throughout much of the
range of this frog has resulted in Great Lakes/St. Lawrence populations being listed as
“Threatened” on the Federal Species at Risk list. Lastly, Leopard Frog (Rana pipiens) is
used as a shallow marsh quality indicator. This species requires connectivity between
wet meadows (typically meadow marsh) and shallow marsh, therefore is an indicator of
connectivity between these two. Also related to connectivity is the likelihood that
Leopard Frogs are more susceptible to roadkill because of their terrestrial nature. The
species may also be an indicator of good water quality as it has been shown to be
sensitive to pesticides, particularly Atrazine (Gibbs et al. 2007).
Since the presence of only a few individuals would not indicate much about wetland
health, only locations where full choruses of each of these frog species were recorded
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have been mapped (Map 8). It is possible that GRCA roadside surveys, which are not
conducted for all parts of the jurisdiction every year, could miss some large populations,
however the map suggests a limited distribution of full choruses for each species
compared with the ELC distribution of wetlands. Additional surveys will be required over
a longer term to determine actual local trends in frog populations.
Wetland areas known to support full choruses of any of these indicator frog species
should be considered candidate areas for Significant Wildlife Habitat designation. In
many cases these will not be Provincially Significant Wetlands, thus these seasonal
concentration areas may have no current protection. As they are discovered, additional
major breeding habitats for sensitive frogs and salamanders should be mapped and
designated as Significant Wildlife Habitat.
Although the GRCA does not monitor mammals, several species have been reported
recently that could act as indicators. Three of these are mustelids (weasel family). The
first is the River Otter (Lutra canadensis), which citizens have reported seeing in parts of
the Ganaraska River watershed. Away from lake systems this species moves between
streams and ponds with good water quality and over large areas to fulfill its fish diet.
Thus the presence of this species suggests good connectivity between bodies of water
with reasonable quality.
The second species is the Fisher (Martes pennanti), a fox-sized predator that requires
large expanses of interior forest (Kurta 1995). Fishers have been reported to breed in
the Ganaraska Forest, suggesting that the forest is large enough to support area-
sensitive predatory mammals. The Pine Marten (Martes americana) is a similar case.
This arboreal weasel requires large expanses of closed coniferous woodland (Kurta
1995), which the plantations in the Ganaraska Forest can apparently provide.
An additonal mammal species, the Black Bear (Ursus americanus), is indicative of good
forest cover. Regular reports of bears suggest that this species is now a local resident in
the GRCA jurisdiction. Although not always popular, black bears are a natural
component of southern Ontario forests, and their return is an indicator of improved
ecological health.
8.0 POTENTIAL NATURAL HERITAGE CONDITIONS
8.1 Introduction
Based on the raster GIS model (described in Appendix 1) two scenarios for improved
natural heritage systems were selected. Because the model is based on criteria related
to ecological function, these scenarios represent incremental targets towards greater
ecological health of the landscape and its watersheds. Vegetation communities most
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suited for the target areas would be dependent on conditions such as soil types,
hydrology, etc. The vector landscape analysis was re-run on the target scenarios and
the improvements in habitat cover and patch conditions are discussed for each of these
in this section.
It is important to emphasize that the target areas represent lands (usually meadow or
agriculture) that have been identified by the model as having the greatest potential to
improve ecological function. However, because most of the lands are privately owned,
these targets should not be viewed as having been “set in stone.” Instead they are
guidelines to help set stewardship priorities, or to identify areas that should be taken into
consideration during proposed land use changes, in which case protection or mitigation
measures, and possible compensation opportunities should be discussed.
8.2 Target System Scenarios
Based on Ecological Land Classification mapping, the current combined cover of forest,
wetland, and beach/bluff habitats amounts to 29,520.2 hectares. This represents 31.8
percent of the total GRCA jurisdiction under natural cover. The first modeled scenario
would increase habitat cover to 40.4 percent (Map 9). Scenario 2 would increase natural
cover to 50.9 percent, which is slightly over 19 percent higher than existing conditions
(Map 14). While an increase in cover is valuable, it is important to keep in mind that the
gains using the model are not based on cover per se, but on the ecological functions that
inform the model criteria. These translate into improved size, shape and connectivity of
the habitat patches.
It is obviously irrelevant to compare the number of patches that scored better or worse
for size shape or matrix influence between existing conditions and the two scenarios
when the number of patches is changing. Nevertheless the graphs on Maps 2, 10 and
15 demonstrate a substantial increase in the amount of cover that scores and ranks in
highest range for patch size with each incremental increase. Furthermore, the average
patch size has increased from 13 ha to 28 ha in Scenario 1 and 31 ha in Scenario 2.
Shape scores, as depicted on Map 3, Map 11 and Map 16 show more habitat scoring in
the lower range from existing conditions to the two scenarios. This is to be expected.
Many formerly isolated and relatively compact patches are now connected to form
larger, but more convoluted patches. Although these have a higher edge-to-area ratio,
because of their increase in size there is an overall increase in interior habitat in the
scenarios.
Scenario 1 shows a relatively small improvement in matrix influence scores over existing
conditions (Map 12). In particular a number of patches in the upper Ganaraska River
watershed have obvious increases, as do patches in the Cobourg Creek watershed and
along the Lake Ontario Shoreline. In this scenario there is no obvious improvement in
patch values for those natural areas within the urban matrix of Port Hope and Cobourg.
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In a counterintuitive outcome, Scenario 2 shows a decrease in habitat area scoring in
the highest range of matrix influence values, although there are big improvements in the
second highest value range (Map 17). This is probably because the habitat patch sizes
have increased so dramatically that there is more chance of there being “urban”
classified areas within the huge 2 km radius around them.
The total score map for the second target scenario (Map 18) shows a decrease in scores
for patches around the Northumberland Forest. This is probably influenced by the
substantial decrease in shape values resulting from the target scenarios for this area,
combined with the counterintuitive change in matrix value described above.
Nevertheless, the graphs on the total score maps (Maps 5, 13, and 18), suggest an
overall shift of habitat area into the higher total score values.
Nuisance Wildlife
If the target natural heritage system promotes an increase in natural cover and its
connectivity, and benefits wildlife by doing so, it is inevitable that questions will be raised
about the potential for an increase in nuisance wildlife. In fact, not only is this unlikely to
happen, but the populations of nuisance species could actually be reduced through an
increase in natural cover.
The species that are usually considered to be problematic are those that eat crops or attack
livestock, damage property, or consume refuse. These include such birds as American
Crows, Blue Jays, European Starlings and Red-winged Blackbirds, and mammals such as
Raccoon, weasels, Striped Skunk, Porcupine, Beaver, Coyote, and Black Bear. Of these,
crow, Blue Jay, Raccoon, skunk, and Coyote are opportunistic omnivores and habitat
generalists. That means they will eat a variety of foods and can make use of just about any
kind of habitat. In essence, they will be around no matter how humans alter the landscape.
If anything, their populations may decrease because they are also considered to be “edge”
species that flourish in fragmented landscapes with a high ratio of habitat patch edge.
Since reducing forest edge and increasing interior habitat is a basic goal of the natural
heritage system, theoretically the populations of these species will actually diminish over
time as the amount of forest cover increases.
White-tailed Deer populations have increased in southern Ontario. These animals
represent a potential road safety hazard, and when abundant can have a negative impact on
populations of sensitive forest plants. Deer have responded well to forest fragmentation
because they too are essentially an edge species. Increasing the amount of forest cover on
the landscape may help stabilize populations.
Red-winged Blackbirds and Beaver are wetland species. The diet of the former is made up
primarily of insects during the breeding season, thus they may actually be beneficial to
humans at this time. It is during late summer and fall migration that blackbirds exhibit
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9.0 GETTING THERE FROM HERE: THE STRATEGY
9.1 Tools for Natural Heritage Protection and Restoration
The most secure way of protecting natural heritage features is through land acquisition,
provided the land is well-managed for conservation of the features in perpetuity. Such
conservation lands can include conservation areas and other conservation authority
properties, Provincial or Federal lands, parks and reserves, or private reserves. Map 19
shows these types of protected areas within the GRCA watershed area, as well as those
flocking behaviour, and may descend on crops. At this time they are not specific to any
particular habitat. Beaver, on the other hand, will make use of any open water area,
including rivers, provided there is a good source of preferred trees nearby. The natural
heritage system model focuses on increasing potential forest cover, and not open water
wetland, therefore should have no impact on beaver populations. Furthermore, one of the
pioneer tree species that may increase in cover when fields are left to revert to forest is
trembling aspen. Beavers favour this species, and where it is available will likely prefer it
over tree species that humans value most.
Porcupine will inhabit deep forest and forest edge. It is debatable that their populations
would increase as a result of more forest cover on the landscape. More forest cover means
more trees for Porcupines to eat. Therefore, although the overall population may increase,
the net impact is likely to be unchanged.
Weasels can be a problem for those who keep chickens. They use both forest and open
country, therefore will not likely be affected by an increase in forest cover. However, one
member of the weasel family, the fisher, is forest dependent. Populations of these animals
have increased in southern Ontario in recent years, and they have been known to prey on
cats in rural areas. This is obviously of concern to cat owners, but considering the amount
of feral cats in the landscape and the tremendous negative impact they have on native
birds, reptiles and small mammals, more Fisher may be beneficial. That one of the main
prey items of Fisher is the Porcupine further suggests a net benefit from the presence of
this species.
Black Bear may benefit from additional forest cover on the landscape, yet they appear to
be expanding their range in southern Ontario already. Whether or not increased
populations of this species will result in an unacceptable number of human-bear conflicts
remains to be seen. From an ecological perspective, bears were native components of
southern Ontario ecosystems, and their return is likely to be beneficial. Should they
become a nuisance, the usual measures would apply.
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lands identified as significant features through provincial policy, specifically Provincially
Significant Wetlands and Areas of Natural and Scientific Interest (ANSI). Clearly much
of the existing, let alone the target natural heritage systems, is lacking any kind of
protection status. The Provincial Policy tools for protection, as well as other means
available, are discussed in this section.
9.1.1 Provincial Policy
The 2005 Provincial Policy Statement (PPS) defines natural heritage features and areas
as:
“features and areas, including significant wetlands, significant coastal wetlands,
fish habitat, significant woodlands south and east of the Canadian Shield,
significant valleylands south and east of the Canadian Shield, significant habitat
of endangered species and threatened species, significant wildlife habitat, and
significant areas of natural and scientific interest, which are important for their
environmental and social values as a legacy of the natural landscapes of an
area.”
Development and site alteration is not permitted in these features “unless it can be
demonstrated that there will be no negative impacts on the natural features or their
ecological functions.”
The province itself defines Provincially Significant Wetlands (PSW) and Areas of Natural
and Scientific Interest (ANSI) using evaluation criteria. Furthermore, the OMNR is
defining habitat requirements for Species at Risk in response to the 2007 Species at
Risk Act. However, the province has left it up to planning authorities to define Significant
Woodlands, Significant Valleylands, and Significant Wildlife Habitat. The revised Natural
Heritage Reference Manual (OMNR 2010) provides guidance on how a planning
authority can do this while acknowledging that alternative approaches may be
acceptable.
Section 2.1.2 of the PPS states that the “diversity and connectivity of natural features in
an area, and the long-term ecological function and biodiversity of natural heritage
systems, should be maintained, restored, or where possible, improved, recognizing
linkages between and among natural heritage features and areas, surface water
features and ground water features.” Thus the Province recognizes the importance of
both ecological function and the natural heritage system that supports this function.
Despite this recognition of ecological function the emphasis of the 2005 PPS is still on
protecting significant features. Even the definition of Natural Heritage System states that
the system is made up of “natural features and areas,” (i.e. the significant features as
defined above). This is problematic for two reasons. One is that, even if an area has
habitat cover below the recommended minimum, only the best of what is left can be
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protected unless a good argument can be made to protect all that remains. Second, if a
natural heritage system is made up of core areas and linkages (or in the case of the
GRCA methodology, a defined area of habitat required to support a set level of function),
how can this policy be used to protect the entire system if it is focused on only the most
significant of what would essentially be components of that system? Even the revised
Natural Heritage Reference Manual, which goes into detail about how to define the
significant features and natural heritage systems separately, fails to demonstrate how to
identify these features within a natural heritage system context.
If a municipality has already defined significant natural heritage features, these can be
incorporated into the natural heritage system. If not, then in the absence of guidance
from the Province, a municipality can attempt to protect a natural heritage system by, for
example, calling all forests within it Significant Woodlands, all wetlands Significant
Wetlands (i.e. those not already identified as PSWs would be locally significant), and
other features such as corridors either Significant Wildlife Habitat, or, Significant
Valleylands. Without accepted approaches however, doing so would require going out
on a limb, and possibly lead to Ontario Municipal Board hearings. Furthermore, the
inconsistency of approaches used by municipalities can undermine their credibility and
defensibility.
Significant Wildlife Habitat should also include such things as seasonal concentration
areas for certain species, as described in the Significant Wildlife Habitat Technical Guide
(OMNR 2000b), whether or not these are located in the defined natural heritage system.
Mapping of such features can be updated on a regular basis as they are encountered.
One example of such an area would be those locations where full choruses of sensitive
frog species (such as those used as indicators) are known to occur. These may be in
wetlands so small that they are not even included in the Ecological Land Classification
mapping.
Using the significant features approach to protect areas of potential habitat will be a
greater challenge, despite the fact that the PPS definition of Natural Heritage System
includes “areas with the potential to be restored to a natural state.” This is because
Section 2.1.7 of the PPS states “nothing in policy 2.1 is intended to limit the ability of
existing agricultural uses to continue.” Given that the model looks for potential
improvements in forest cover primarily on agricultural lands, no protection or restoration
of these lands will be possible without cooperation of the landowner. Fortunately,
agricultural land between patches of woodland or other habitats does provide
connectivity for some species, therefore even while it is actively used for crop production
it contributes to the defined target natural heritage system.
Based on these challenges it is recommended that the target natural heritage system be
considered conceptual. It is a framework for decision-making based on a long-term
vision. It is also a means of identifying priority areas for landowner contact related to
stewardship – particularly tree planting. This is not to suggest that existing and potential
habitat is expendable. Ideally there would be no net loss at a minimum and a
consideration of the target system in municipal planning. Existing features should be
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protected to the greatest extent possible, and potential habitat areas given serious
consideration. Should development threaten either, compensation should be sought.
The target natural heritage system should also act as a screening tool for development
applications, for example it could highlight the need for an environmental impact study
should the municipality require this through its protection policy. Within the system itself,
municipal or conservation authority policy may restrict some forms of development, while
development on adjacent lands may require mitigation such as buffers to ensure no
negative impacts on the system. Ideally existing habitat within the defined target system
would be protected. On the other hand, development proposals in areas identified as
having restoration potential to achieve the target system may require a compensation for
loss process to ensure no net loss of potential, particularly within the vicinity of the
proposed development.
The target natural heritage systems in the two scenarios should be considered as
guidelines towards achieving greater ecological health and improved biodiversity
conservation in the landscape. The boundaries of the system must be flexible enough to
respond to those landowners within the defined area who are not interested in the
project, versus those that are outside the system that are interested in improving natural
heritage values on their properties. Meeting the targets will require innovative
approaches and landowner cooperation, and it is recognized that not all landowners will
show an interest in the concept even if financial or other compensation for a change in
land use is offered. The tools for building and sustaining the system include education,
stewardship, land acquisition and securement, alternative land uses, integration into the
watershed planning process, provincial and municipal policy, and regulation tools.
To determine how best to use provincial policy to protect and restore a target natural
heritage system the GRCA will:
1. Continue to consult with other conservation authorities with respect to their
approaches.
2. Consult with municipal partners, outlining available options and their
consequences.
3. Work with municipal partners to define provincially significant features in relation
to the natural heritage system.
4. Work with municipal partners to develop policies for natural heritage features and
the natural heritage system, including for protection, compatible land uses, and
mitigation and compensation in the event of development proposals.
9.1.2 Public Education
Although Canada is a signatory nation to the 1992 Convention on Biological Diversity
and both the nation and the province of Ontario have biodiversity strategies, it is
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surprising to find that the majority of citizens have little understanding of what
biodiversity is and even less knowledge about the basic issues in conservation such as
habitat fragmentation as discussed in Section 3.1. Many Canadians have an idea about
what an ecosystem is, however few have a good knowledge of the species that make up
those systems or how they interact with other species and the environment. In addition,
the values of ecosystems to individuals and society are under-appreciated. Under these
circumstances it can be difficult to gain public support for natural heritage protection.
Nevertheless, many private landowners already appreciate natural heritage values and
have a strong conservation ethic. An improvement in ecological literacy, especially with
respect to recent issues in conservation science (e.g. conservation biology and
landscape ecology) would enhance these existing sentiments and possibly gain new
converts. The GRCA will therefore:
1. Use existing and develop additional communication materials on southern
Ontario biodiversity and conservation issues.
2. Target the media with more stories related to natural history and ecology.
3. Foster a greater appreciation for wildlife and ecosystems among landowners
through direct contact, displays, and workshops.
4. Engage schools in conservation programs through the Ganaraska Forest Centre
and through classroom education.
9.1.3 Private Landowner Stewardship
Although the Province recently cut support for Stewardship Councils there remains a
strong interest among landowners for private land stewardship. Many conservation
authorities promote stewardship activities through partnerships with local municipalities.
The GRCA’s Clean Water-Healthy Land Stewardship Program is an example of such a
project. To continue promoting and undertaking stewardship for the benefit of terrestrial
natural heritage the GRCA will:
1. Use the target natural heritage systems as a tool to set private land stewardship
priorities.
2. Maintain the Clean Water-Healthy Land Stewardship Program and tree planting
program.
3. Maintain existing, and become involved in additional partnerships that promote
and undertake private land stewardship.
4. Where feasible target specific rare vegetation communities such as tallgrass
prairie through stewardship activities.
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9.1.4 Land Acquisition and Securement
One of the surest means of protecting a significant area is securement. This can take
the form of purchasing properties, receiving property donations, or placing conservation
easements on privately held lands. A number of groups, including the Nature
Conservancy of Canada, the Kawartha Land Trust and the Northumberland Land Trust,
have been actively securing properties in or around the GRCA jurisdiction. The GRCA
itself has a history of land securement, including acquiring properties to expand the
Ganaraska Forest. The target natural heritage system can provide useful guidance for
land securement. For example the presence of a property within or adjacent to the
system could enhance its conservation value. In future the GRCA will:
1. Update land acquisition priorities based on the natural heritage system.
2. Use the natural heritage system as a tool when considering the merit of property
donations.
3. Consider securement options for protecting particularly important components of
the natural heritage system.
4. Cooperate with other securement-focussed organizations to help protect the
natural heritage system.
9.1.5 Alternative Land Use Options
The impact of various land use types on natural heritage systems can range from
negative to benign, to beneficial. For the most part urban land uses have negative
impacts because of the intensity of human use. While cities may have limited capacity
to support area sensitive species (Environment Canada 2007), by providing green
infrastructure they can become more compatible with natural heritage systems. For
example, improving the urban forest and planting native wildflower gardens can provide
wildlife habitat, reduce pesticide use and water consumption, and help regulate local
climate (Evergreen Foundation 2001).
Although they displace what were formerly natural ecosystems and are managed
primarily for the benefit of humans, agricultural lands tend to have fewer negative
impacts on biodiversity than urban areas, and in some cases can provide valuable
habitat. For example pasture can support many grassland sparrows and in some cases
the endangered loggerhead shrike. Hay fields can provide valuable habitat for the
Bobolink, (now designated as a threatened species) provided they are not harvested
before the breeding period ends (Ross 2010). Nevertheless, monoculture crops may
require high inputs of fertilizers and pesticides that can have negative impacts on natural
areas and species, while providing minimal habitat in themselves (Shiva 1993).
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Research has been underway to find ways to make agriculture more compatible with
environmental protection. An excellent example is the Alternative Land Use Services
(ALUS) project in Norfolk County, Ontario which seeks to develop partnerships with
landowners, to undertake research into alternative agricultural practices, and to promote
compensation for farmers who provide ecological services (Bailey and Reed 2004).
ALUS has been very successful so far and can be seen as a model for similar efforts
elsewhere in southern Ontario.
Agroforestry is the practice of integrating trees with agricultural crops and/or livestock
(Laine 2008). This can range from planting a treed shelterbelt to managing a woodlot for
non-timber forest products. Agroforestry could be a key approach towards building the
target natural heritage system because it can involve increasing tree cover on the
landscape to improve the function of the system while at the same time resulting in crops
that provide income to landowners.
One form of agroforestry, known as Analog Forestry, may be a particularly useful
approach. Analog Forestry was originally applied in Sri Lanka to restore lands that were
heavily degraded by tea plantations (Senanayake and Jack 1998). It involves the
restoration of degraded lands by establishing vegetation cover made up of native forest
plants that are useful to wildlife mixed with native and non-invasive non-native species
that provide food, construction materials and income to the landowner or community.
Analog forests are designed to mimic natural succession, with valued species that are
ecological “pioneers” planted initially, followed over time with the planting of species
adapted to later successional stages. The resulting analog forest has a structure and
functions similar to a natural forest and requires no fertilizer or pesticide inputs. Applying
this approach to lands identified as target areas can potentially build the natural heritage
system and restore many ecological functions to the landscape without taking land out of
production.
Analog Forestry has more potential in tropical regions because of the higher diversity of
non-timber species that can be planted such as fruits, nuts, coffee, latex, etc.
Nevertheless, the potential of temperate non-timber forest products such as maple
syrup, ginseng, raspberries, walnuts etc. within an analog forest context is worth
exploring through experimentation. Marketing of such crops could be enhanced with
organic and environment-friendly certification.
Whether they were planted as part of an analog forest, a plantation, or an attempt to
recreate natural forest, mature trees are a crop that can be selectively harvested for
income. It can be argued that quality hardwood may be worth more in the long run than
growing crops such as corn over the same period. The challenge is how to compensate
for the lost short-term income while the timber crop matures. Subsidies in the present
for a share of the future profit may be the key to making such a program viable. Such
subsidies should take into consideration the additional values provided by the trees as
they mature, not only in improving ecological function through the natural heritage
system, but through soil improvement, water retention, local climate regulation, carbon
sequestration and recreational and aesthetic values.
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Alternative forms of energy may re-shape the agricultural landscape in the near future,
most literally through the establishment of solar farms and wind farms. Obviously
displacement of natural cover to establish these would not benefit a natural heritage
system. Furthermore, there is evidence that wind turbines do have an impact on birds
and bats. For example, on Wolfe Island in the St. Lawrence River 602 birds and 1,270
bats were killed within a sixth month period following the establishment of 86 wind
turbines (Bell 2010). More studies are needed to determine the potential impacts of
these structures on biodiversity as well as where they might be situated to have minimal
impact.
The demand for biofuel crops could also potentially result in the loss of additional natural
cover. In the case of corn planted for ethanol production this would simply increase the
cultivated area of monoculture row crop, and the usual environmental impacts
associated with this.
In eastern Ontario Switchgrass has been planted for the production of fuel pellets that
are used in stoves to heat buildings. Fields of Switchgrass may have the capacity to
support some grassland breeding birds such as Bobolink, however as a monoculture
they have limited value for biodiversity. In contrast, areas with dry sandy soils may have
the potential to grow prairie plants for pellet production. Studies in Minnesota (Tilman et
al. 2006) have demonstrated that a mix of prairie grasses and forbs can produce more
energy than grass monocultures. Provided that it does not displace existing tallgrass
prairie remnants or remove tallgrass restoration opportunities, this approach may have
tremendous potential because it could result in “productive prairies” that mimic native
prairies while providing habitat for a variety of prairie-dependent birds, insects and other
species. In short, productive prairies such as this could complement or enhance the
natural heritage system.
To help reduce the negative impacts of urban and agricultural land uses and to make
them more compatible with a viable natural heritage system the GRCA will:
1. Promote the greening of urban areas and provide advice and referrals to
individuals and city departments about planting native wildflower gardens and
native trees to promote biodiversity.
2. Promote and where possible support agricultural projects that enhance the
natural heritage system.
3. Where feasible work with landowners to experiment with agricultural alternatives
such as agroforestry and productive prairie projects.
9.1.6 Management of Conservation Authority Lands
In recent times the focus of government funding programs for stewardship has been on
private lands, leaving public lands with limited support for maintenance. This is ironic
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considering that these lands exist for environmental conservation purposes. They are
meant to be reservoirs of biodiversity and ecological function and examples of healthy
natural areas, while at the same time having an important role to play in water
management, research and the appreciation for nature. In some cases they harbor
species at risk and rare vegetation communities such as tallgrass prairie. Yet
conservation lands are becoming degraded from high recreational pressures, invasive
species, or plain neglect because there is limited funding available to monitor and
respond to these conditions or to improve the services they provide. With respect to
conservation lands the GRCA would like to:
1. Undertake detailed ELC mapping and species inventories.
2. Cooperate with academic institutions to undertake research on the impacts of
recreational use.
3. Identify areas for ecological restoration, including control invasive species and
erosion.
4. Identify opportunities to improve public outreach and education opportunities.
5. Update existing management plans based on the above.
9.1.7 Integration of Terrestrial Natural Heritage with Other Watershed Management Programs
While the focus of this strategy is terrestrial natural heritage, ecological integrity involves
much more than this. Ecological integrity involves aquatic ecosystems, as well as
maintaining basic ecological cycles, including nutrients, the hydrological cycle, and
carbon and nitrogen cycles. Ideally, a natural heritage system would contain all of these
components as well as geological features. While these were beyond the scope of this
document, the relationships between these other ecosystem elements must be
considered.
Watershed management by Conservation Authorities, including the GRCA, involves
measuring and monitoring hydrological systems and aquatic ecosystems. For the most
part each element has been addressed on its own. Therefore there is a real need for an
integrated approach to watershed monitoring and management. In this regard the
GRCA shall continue to develop an integrated watershed monitoring program that will:
1. Identify areas of overlap and interdependencies between watershed
ecological elements and hydrological and geological features.
2. Determine if there may be suitable indicators for these relationships.
3. Develop and implement an integrated watershed monitoring program that
addresses the relationships between these elements.
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9.2 Dealing With Specific Conservation Concerns
9.2.1 Species at Risk and Rare Species
In Ontario Species at Risk (SAR) are divided into four categories: Endangered,
Threatened, Extirpated and Special Concern. At least 37 terrestrial SAR have been
historically found, or could be currently present in the GRCA jurisdiction (Table 1).
Table 1 Terrestrial Species at Risk in or potentially in the GRCA watershed
Common Name Latin Name Provincial
Status Federal Status
Henslow’s Sparrow Ammodramus henslowii END END
Short-eared Owl Asio flammeus SC SC
Whip-poor-will Caprimlugus vociferus THR THR
Chimney Swift Chaetura pelagica THR THR
Snapping Turtle Chelydra serpentina SC SC
Black Tern Chlidonias niger SC
Common Nighthawk Chordeiles minor SC THR
Northern Bobwhite Colinus virginianus END END
Eastern Wood Pewee Contopus virens SC
Yellow Rail Coturnicops noveboracensis SC SC
Monarch Danaus plexippus SC SC
Cerulean Warbler Dendroica cerulea SC SC
Bobolink Dolichonyx oryzivorus THR THR
Blanding’s Turtle Emydoidea blandingii THR THR
Peregrine Falcon Falco peregrinus THR THR
Northern Map Turtle Graptemys geographica SC SC
Bald Eagle Haliaeetus leucocephalus SC
Eastern Hog-nosed Snake Heterodon platyrhinos THR THR
Barn Swallow Hirundo rustica THR THR
Wood Thrush Hylocichla mustelina THR
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Common Name Latin Name Provincial
Status Federal Status
Least Bittern Ixobrychus exilis THR THR
Butternut Juglans cinerea END END
Eastern Milk Snake Lampropeltis triangulum SC SC
Loggerhead Shrike Lanius ludovicianus END END
Red-headed Woodpecker Melanerpes erythrocephalus SC THR
Little Brown Myotis Myotis lucifugus END END
Northern Myotis Myotis septentrionalis END END
American Ginseng Panax quinquefolius END END
Eastern Prairie Fringed Orchid
Platanthera leucophaea END END
Western Chorus Frog Pseudacris triseriata THR
King Rail Rallus elegans END END
Eastern Meadowlark Sturnella magna THR THR
Eastern Ribbonsnake Thamnophis sauritus SC SC
Eastern Musk Turtle Sturnothernus odoratus THR SC
Golden-winged Warbler Vermivora chrysoptera SC THR
Canada Warbler Wilsonia canadensis SC THR
Hooded Warbler Wilsonia citrina SC THR
Provincial policy and the provincial Endangered Species Act (2007) require that species
at risk and their habitats be protected. Therefore, where these are known to exist or
where they are discovered in the future the provincial legislation will apply. During the
course of reviewing planning applications the GRCA may identify an “Element
Occurrence” of a species at risk or rare species based on historical records maintained
by the Natural Heritage Information Centre. In the case of species covered by the Act,
the proponent is directed to the Ontario Ministry of Natural Resources.
Promoting protection and restoration of natural areas, as well as improvements in the
size, shape and connectivity of habitat patches, should contribute to the maintenance of
viable populations of most species requiring specific habitat (as opposed to habitat
generalists), regardless of how rare they are. However, not all SAR are in trouble
because of habitat loss or fragmentation. Butternut (Juglans cinerea), for example, is
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threatened by the butternut canker disease. The loggerhead shrike (Lanius
ludovicianus) has declined dramatically despite the presence of what appears to be
suitable habitat. Such species require special attention, and are subject to provincial
recovery plans.
American Ginseng (Panax quinquefolius)
Many species that have yet to be listed as SAR are nevertheless of conservation
concern because of disturbing population declines throughout their range. These
include a number of Neotropical and other migratory birds of both woodlands and
grasslands. Other species are simply uncommon naturally because they are restricted
to rare habitat types, or because they are particularly sensitive to disturbance or
environmental degradation. It is hoped that most of these are captured in the natural
heritage system. Should populations be discovered that are not protected, consideration
should be given to defining the areas as significant wildlife habitat. The same would
apply to seasonal congregation areas such as communal hibernation sites or nesting
colonies.
In the past GRCA has been actively involved in Species at Risk projects, for example
through the Rice Lake Plains Joint Initiative partnership. One focal species has been the
Eastern Hog-nosed Snake (Heterodon platyrhinos), an unusual and interesting reptile
whose Ontario range is restricted to areas with sandy soils. Future actions by GRCA in
relation to Species at Risk should include:
1. Develop a list of local species of concern based on rarity.
2. Create a database to record sightings of local species of concern.
3. Continue to lead, support or be an active partner in SAR projects.
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4. If support is available make an effort to revisit sites with old records to confirm
whether or not SAR can still be found at historical localities and report results to
the Natural Heritage Information Centre.
5. Conduct inventory work and contact local naturalists to determine additional
locations of rare species and species at risk.
6. Consider the needs of species at risk in management of the Ganaraska Forest,
including forestry and recreational activities.
Eastern Hog-nosed Snake (Heterodon platyirhinos)
9.2.2 Grassland Birds
Bird monitoring programs have provided evidence that a number bird species associated
with open grasslands are experiencing steep, long-term population declines. These
include the Eastern Meadowlark (Sturnella magna), Savannah Sparrow (Passerculus
sandwichensis), Grasshopper Sparrow (Ammodramus savannarum) and others. Two
endangered bird species in Ontario, the Loggerhead Shrike and Henslow’s Sparrow
(Ammodramus henslowii), are also associated with grasslands, as is the Bobolink
(Dolichonyx oryzivorus), which was designated a threatened species in Ontario in 2010.
A number of land use issues have been implicated in these declines. They include the
loss of old field habitats to urbanization, use of more intensive agricultural methods,
mowing of hayfields during breeding season, and ecological succession of meadows
and pasturelands to shrub and forest habitats. Widespread use of toxic pesticides on
the wintering grounds is also believed to be a contributing factor (Stutchbury 2007).
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The decline of grassland birds has received a great deal of attention by conservation
groups over the last few years. What tends to be forgotten, however, is that numerous
forest-dependent birds and other species are also in decline. This leaves us with a
conservation dilemma. If most of southern Ontario was historically under forest cover
and some forest birds are in decline, should these and other forest-dependent
organisms not be of higher concern than grassland birds? Would the ecological health
of the landscape - the quality of soil, the quality and quantity of water, and the local
climate - not be better if mature forest was again the dominant vegetation type? Are not
grassland bird populations artificially inflated compared to historical conditions when
grasslands were relatively rare and disturbance-dependent? In short, how concerned
should we be if populations of grassland birds are in decline? And should we wait to see
if the populations of these birds stabilize at a lower, but sustainable level?
Complicating the situation is the issue of geographical representation and responsibility.
The bobolink is a case in point. The historical center of this species’ distribution was in
the tallgrass plains of the Midwestern United States. However, habitat loss and
intensive agricultural practices in the Midwest, coupled with clearing of forests further
east by European settlers resulted in a range shift for much of the population. The bulk
of the North American population now appears to be east of the original range, including
Ontario, meaning that for long term persistence of the total population, these areas have
the responsibility for maintaining more individuals than would likely have occurred
historically (McCracken 2005). This implies that we must conserve more grassland than
would have occurred historically.
Bobolink (Dolichonyx oryzivorus) Source: S. Maslowski (Wikimedia)
The conservation of grassland birds presents numerous dilemmas. For example, if the
natural tendency of ecological succession is to produce forest, then active management
will be required to maintain grassland. Some of that active management is currently in
the form of hayfields and pasture, the goals of which do not normally include supporting
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birds. Such practices frequently shift from productive fields to fallow fields. Which
means that, even with programs in place to encourage improved management practices,
some form of inventory would be necessary to ensure that enough suitable habitat is
available at any one time and consistently to sustain grassland bird populations. This
would have to be done at a variety of scales from local to provincial.
How can the needs of grassland birds be addressed through a natural heritage system,
especially considering that the modeling approach used by GRCA considers fallow fields
as areas that may have potential to increase forest cover? One approach would be to
identify and incorporate grasslands into the defined system. However, the fact that
grasslands are ephemeral in nature because they undergo ecological succession or are
subject to changes in land use makes this approach challenging. Another approach
would be to attempt to ensure that grasslands are well-represented in the landscape
matrix surrounding the natural heritage system. This too would be a challenge, not only
for the above reasons, but because it would involve a mammoth effort to coordinate the
land use activities of many land owners.
Both of these approaches would involve maintaining unnatural cover that benefits
grassland birds (hayfields and pasture) or, at best semi-natural cover (old fields). A
more practical approach would be to step up the effort to restore tallgrass prairie and
savanna – a natural vegetation community type - wherever it is feasible to do so. By
doing this one would both increase the cover of this threatened ecosystem, and help to
stabilize or increase populations not only of grassland birds, but of all the other
uncommon species that rely on these habitats.
To address the decline of grassland bird species the GRCA will:
1. Solicit support and partnerships for surveys, mapping and monitoring of
grassland birds.
2. Promote public awareness about grassland birds and species at risk.
3. Undertake analyses to determine how grassland priorities might best be
incorporated into natural heritage system planning.
4. Where appropriate, advise or work with landowners to maintain or create habitat
beneficial to grassland birds.
9.2.3 Rare Tallgrass Communities
Tallgrass prairie and savanna are grass-dominated ecosystems adapted to drought
conditions. Historically they were present on large portions of natural sand plains in
southern Ontario such as the Lake Erie Sand Plain and the Rice Lake Plains on the Oak
Ridges Moraine. Occasional fires prevented woody vegetation such as trees from taking
over, allowing the grasses and many species of fire-tolerant wildflowers to survive.
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Without trees, tallgrass ecosystems were among the easiest areas for settlers to clear
for agriculture. However the dry sandy soils were not conducive for many crops, and
farms on these sand plains were often abandoned. Without the deep roots of prairie
plants to hold the soil, some of these abandoned areas became blow-sands. To
stabilize the soil tree planting programs were initiated in the 1920s and 1930s. These
programs were very successful. However it wasn’t until the latter half of the 20th Century
that ecologists and biologists realized that prairie was historically present on these lands,
and that the few remnants made up a very small percent of the original cover in North
America – making tallgrass communities a critical conservation concern.
At present no GIS model exists to determine priority areas for increasing tallgrass prairie
and savanna cover. However, mapping and inventory results of tallgrass in the
Peterborough District has been compiled by the Ontario Ministry of Natural Resources
(White 2003). This is depicted on Map 20. This mapping can be overlaid on the
modeled natural heritage system to ensure its inclusion. Existing soils mapping can also
be used to determine where there is potential for tallgrass. The merits of planting
tallgrass versus forest in stewardship efforts can then be based on this information
coupled with landowner preferences and the modeled system that is based on showing
potential improvements in forest cover. It is suggested that for areas where there is
clear potential to greatly increase forest patch values, forest cover should be the
preferred option. Other areas on sandy soils can be considered for their potential to
increase tallgrass cover. It must be kept in mind, however, that to maintain tallgrass a
commitment to active management such as prescribed burns is necessary. Otherwise
natural succession will result in the eventual return of forest.
The GRCA has been actively involved in tallgrass prairie restoration work since 2005.
Future work to address this conservation issue could include:
1. Continue to solicit support for, maintain and restore tallgrass remnants on GRCA
properties.
2. Work to ensure that tallgrass remnants are not negatively impacted by multiple
use management of the Ganaraska Forest.
3. Where appropriate incorporate tallgrass prairie restoration or creation into
landowner stewardship programs.
4. Incorporate tallgrass into Ganaraska Forest Centre education programming.
5. Continue GRCA participation in the Rice Lake Plains Joint Initiative.
6. Investigate the potential for restoring tallgrass prairie along roadsides.
7. Support the efforts of Tallgrass Ontario to implement the provincial tallgrass
recovery strategy.
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Prescribed burn at Ochonski Prarie, Ganaraska Forest
Tallgrass Prairie Restoration, Ganaraska Forest Centre
9.2.4 Coastal Zones
Coastal communities include beach and bluff as well as coastal wetlands. Near-coast
zones refer to lands surrounding large bodies of water, such as those within 2 km of
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Lake Ontario. With the exception of the major coastal wetlands (which are often
associated with creek mouths), these areas are generally not considered in watershed
planning because they are not found within defined major watershed boundaries. As a
result they require particular attention.
The chief concern with beaches and bluffs is their rarity and vulnerability. By nature
these are dynamic ecosystems that can shift with water levels and the action of waves,
ice and seepage. Native beach vegetation communities have been found in only a few
locations on the Lake Ontario shoreline within the GRCA jurisdiction, and where they are
found they tend to be degraded. Bluffs, such as the Bondhead Bluffs, feature unusual
vegetation communities such as hanging fens that harbor rare plant species.
Coastal wetlands, including those on large inland water bodies such as Rice Lake, tend
to be dominated by expansive marshlands. In addition to their values for filtering water,
protecting shorelines and providing important fish habitat these areas are a preferred
habitat of rare area-sensitive bird species, including Bald Eagle (Haliaeetus
leucocephalus), Black Tern (Chlidonias niger), Least Bittern (Ixobrychus exilis), Sandhill
Crane (Grus canadensis), Yellow Rail (Coturnicops noveboracensis) and King Rail
(Rallus elegans).
Near-coast zones, especially those around the Great Lakes, are of particular concern for
migratory species. Long distance migrants such as songbirds rely on natural habitat in
these areas for staging, that is for food and cover before or after crossing Lake Ontario.
Monarch butterflies, now a species at risk, also require open fields with native
wildflowers as well as trees for roosting while they wait for optimum weather conditions
for crossing the lake. Efforts by the GRCA to deal with coastal natural heritage should
include:
1. Continue involvement in the Durham Coastal Wetland Monitoring Project.
2. Expand coastal wetland monitoring to Northumberland County to include
important areas such as the Carr Marsh, as well as wetlands on Rice Lake.
3. Continue field surveys and complete a background report on the terrestrial
natural heritage of the Lake Ontario coastal zone within the GRCA jurisdiction,
beginning with the Municipality of Clarington and expanding into the Municipality
of Port Hope and the Township of Hamilton.
4. Work with municipal partners to protect rare and sensitive coastal ecosystems
through the planning process and through public education, signage, etc.
5. Garner support and partnerships to restore degraded beach and bluff
communities.
6. Work with private landowners to protect and restore habitat for migratory birds
and butterflies.
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9.2.5 Climate Change
Climate change models for Ontario predict a warming trend (Columbo et al. 2007). This
will affect species and vegetation communities in complex ways (Varrin et al. 2007). The
Ontario Breeding Bird Atlas (Cadman et al. 2007) shows that numerous bird species,
including Northern Mockingbird, Blue-gray Gnatcatcher and many others, are already
expanding their breeding range substantially further north in the province. Although not
proven, it is possible, if not likely that this is a response to climate change. The
advantage birds have over other species is long distance flight.
Models show that the climate envelopes for some tree species are expected to shift
northward (Lovejoy and Hannah 2006). However, this is not to imply that the trees
themselves will be capable of doing so. Unlike the birds, dispersal capacity of most tree
species is too limited to keep pace with projected climate conditions.
Some plant and animal species have the capacity to move further and faster than others,
which means that if there is a need to move northward in response to changing climate,
the species composition of ecosystems will change. We will have some northern
species lagging behind as some southern species move forward. A positive way of
looking at the resulting conditions is to consider that “novel ecosystems” may continue to
function and provide services. However, climate change will put tremendous stress on
existing ecosystems, diminish biodiversity and reduce their function and productivity.
The species that will be the real losers as the climate changes will be those that have
limited dispersal capacity and/or are habitat specialists. They will not be able to move
fast enough or will not be able to find suitable habitat. The situation will be greatly
exacerbated for many species and communities in southern Ontario because of habitat
fragmentation. Even without climate change this is already a serious threat to
biodiversity.
Migratory species will also be at a disadvantage, especially Neotropical migratory birds.
These time their return flight from the south to take advantage of warm spring conditions
gradually shifting northward. As trees leaf-out the insects that feed on them, such as
“inchworm” caterpillars emerge, as do flying insects. These are critical food resources.
Sudden cold snaps can eliminate this food supply. Early or late warm conditions can
mean the resources aren’t there when they are needed during parts of the migration or
when the birds reach the breeding grounds (Root and Hughes 2005).
Because climate envelopes will shift and species must move in response, improving
habitat connectivity will be a crucial step in our dealing with climate change. Defining
improved habitat cover targets and meeting these through tree planting and ecological
restoration will not only improve landscape connectivity for the benefit of biodiversity, it
will sequester large amounts of carbon. Thus building natural heritage systems is one of
the most important things we can do to respond to climate change.
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In their approach to dealing with climate change in relation to natural heritage the GRCA
will:
1. Promote and participate in partnerships (with municipalities, other conservation
authorities, non-profit organizations and government) to identify, mitigate and
adapt to the local impacts of climate change.
2. Work with municipal partners in the development climate change strategies.
3. Develop a strategy to determine how GRCA should respond to climate change.
4. Use and provide data collected through GRCA monitoring programs in the
identification of the potential impacts of climate change and mitigation measures.
5. Provide expertise and outreach regarding potential climate change impacts on
natural heritage.
6. Work to promote and improve the natural heritage system.
9.2.6 Invasive Species
Dealing with invasive species may not have been a priority for conservation authorities in
the past, however some invasive plants such as Pale Swallowwort or Dog-strangling
Vine (Cynanchum rossicum) have recently become so pervasive that they threaten the
ecological health of Conservation Authority properties and have become a major
concern for private landowners. Furthermore, the recent arrival of Giant Hogweed
(Heracleum mantegazzianum) poses a health hazard that has led to growing public
concern. Complicating matters, the Ontario pesticide by-law has placed some
restrictions on the use of chemical herbicides in the control of invasive plants and there
is considerable public confusion with respect to the circumstances in which the by-law is
applied. Thus, in responding to the threats posed by invasive species there is a need to
clarify the roles and responsibilities of the various agencies that manage lands or protect
natural heritage features.
Two of the terrestrial insect invaders, the Asian Long-horned Beetle and the Emerald
Ash Borer remain the responsibility of the Canadian Food Inspection Agency (CFIA),
hence the GRCA role would be to merely to post existing educational materials and refer
potential sightings of these beetles to the CFIA. With respect to terrestrial ecosystems
the primary threats are from invasive plant species, thus these should be the initial
focus. To deal with the problem the GRCA will:
1. Raise public awareness of the invasive species issue through distribution of
educational materials and through media.
2. Where appropriate act as an information source on the ecology and management
of priority invasive species.
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3. Develop an invasive species response plan for the GRCA watersheds that
identifies and maps priority species and outlines the potential roles of the GRCA
in dealing with this issue, including management of GRCA properties and private
land stewardship.
4. Work with municipal partners and other conservation authorities to develop
response strategies to invasive species.
5. Actively map invasive species occurrences and contribute data to provincial
tracking systems.
9.2.7 Roads
A number of conservation authorities have been involved with the Ontario Road Ecology
Group (OREG) and are incorporating this issue in their natural heritage work. The
GRCA has been following OREG’s progress and participating in symposia. In 2010
GRCA experimented with a simple road density measure of length of road in kilometers
per square kilometer of area using UTM squares and watershed units. Next steps
should include:
1. Continue using road density measures and compare them to collected data on
species presence, benthic invertebrate diversity and water quality to determine
the values of using road density in watershed planning.
2. Undertake a survey and mapping study of bridges and culverts where the natural
heritage system is bisected by roads in order to determine the degree of
connectivity offered by these structures for various terrestrial wildlife species.
3. Partner with other groups and municipalities to develop a local road ecology
program and through this program a) undertake a study to determine wildlife
crossing hotspots through GIS analysis and roadkill surveys; b) determine where
mitigation measures might be undertaken such as posting signage or creating
ecopassages; c) identify and make use of opportunities for roads to complement
the natural heritage system, such as through the establishment of roadside
prairie
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Turtle crossing sign erected in Bewdley
9.2.8 Recreational Use
GRCA properties and conservation areas offer excellent recreational use opportunities
to the public such as hiking, cross country skiing, bird watching and fishing. In addition
the Ganaraska Forest offers opportunities for hunting and off-road vehicle use.
However, there are signs of natural feature degradation resulting from these uses such
as the introduction of invasive plants, refuse, and erosion. In order to continue to
provide recreation opportunities while maintaining ecological integrity the GRCA should:
1. Undertake assessments of the impacts of recreational use on natural heritage
features, where possible working with educational institutions and students in the
process.
2. Have maintenance staff keep a record of such disturbances and report them to
the GRCA ecologist.
3. Identify and prioritize these impacts in updated property management plans.
4. Seek funding sources for addressing these impacts through stewardship, and
where possible involve the public and private sector in response actions.
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9.2.9 Urbanization
While cities and towns have numerous negative impacts on biodiversity and ecological
health there are many things that can be done to reduce the problems and make urban
areas more natural heritage-friendly (Schaefer et al. 2004). In fact there is a growing
movement to make cities “biophilic,” that is more nature and life-friendly through urban
design and planning (Beatley 2011). Actions include native plant gardening in yards
and parklands to increase biodiversity and support pollinator insect populations,
promoting landscaping with native plants in industrial and commercial areas, reducing
the impacts of cats and windows on birds, establishing green rooftops, etc. It is
recommended that the GRCA:
1. Research and document any existing local programs for urban biodiversity and
natural heritage.
2. Identify municipal parks, forestry, and planning staff that may have an interest in
urban biodiversity issues and action.
3. Develop an urban biodiversity program to engage the public, municipalities and
partner organizations in promoting biophilic cities.
4. Work in partnership with other organizations to develop and/or distribute existing
education materials about urban biodiversity.
5. Where feasible provide expertise and resources to undertake private and public
stewardship projects within the urban setting.
6. Consider incorporating urban biodiversity issues in educational programs.
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GLOSSARY OF TERMS
Agroforestry: Combining trees with crop agriculture as a windbreak, to produce shade,
or to provide additional crops.
Biodiversity: The variety and variability of life as expressed through genes, species
and ecosystems.
Biofuel: Organic material as a fuel source, ranging from grasses, to manure, to alcohol
distilled from plant material.
Cascading Effects: A series of impacts, often unpredictable, based on disturbance of
an ecosystem (e.g. removal of a species).
Connectivity: A measure of how connected or spatially continuous a corridor, network,
or matrix is. Structural connectivity is the placement of patch and corridor features in the
landscape. Functional connectivity is the degree to which an organism can navigate
through this structure.
Corridor: A strip of a particular type that differs from the adjacent land on both sides. A
linear structural element in the landscape that provides movement opportunities for
organisms or ecological processes.
Ecological Health: The condition of an ecosystem, through its structure and functions,
that permits the maintenance of biological diversity, biotic integrity, and biological
processes over time.
Ecological Integrity: The quality of a natural, unmanaged or managed ecosystem in
which the natural ecological processes are sustained, with genetic, species, and
ecosystem diversity ensured for the future.
Ecopassage: A man made structure, such as a culvert or overpass, designed for
wildlife to avoid roads.
Fitness: The ability of a population to survive and adapt to environmental change based
on genetic traits.
Forest Interior: The dark, cool, and moist conditions that occur deep within a
woodland, commonly defined as occurring further than 100 metres from the outside
edge.
Habitat: The ecosystem(s) where a species lives, or the conditions within that
ecosystem that a species requires.
Habitat Configuration: The specific arrangement of habitat elements that is found in
different places.
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Habitat Fragmentation: The process of gradually breaking habitat patches into ever
smaller and more isolated pieces.
Inbreeding Depression: The mating among close relatives which produces few
offspring, and offspring that are weak or sterile.
Indicator Species: Species chosen to monitor environmental change because they are
associated with very specific conditions and therefore their presence or absence
suggests the status of those conditions.
Invasive Species: Alien species whose introduction or spread threatens the
environment the economy, and/or society, including human health.
Keystone Species: A species whose removal causes widespread ecological effects.
Landscape Matrix: The background ecosystem or land-use type in a mosaic.
Metacommunity: A collection of ecological communities connected by species
dispersal.
Metapopulation: The sum total of all the individual populations of a species within the
landscape
Natural Heritage: Includes geological features and landforms; associated terrestrial
and aquatic ecosystems; their plant species, populations and communities; and all
native animal species, their habitats and sustaining environment.
Natural Heritage System: A system made up of natural heritage features and areas,
linked by natural corridors which are necessary to maintain biological and geological
diversity, natural functions, viable populations of indigenous species and ecosystems.
These systems can include lands that have been restored and areas with the potential to
be restored to a natural state (PPS 2005).
Negative Edge Effects: The detrimental influences on a habitat patch resulting from
exposure to the landscape matrix, such as wind, predation, invasive species, etc.
Novel Ecosystems: Ecosystems made up of components that did not evolve or
naturally occur together, such as those that are dominated by exotic species.
Parasitism: The action of a parasite. One organism benefitting from another organism
without reciprocity.
Patch: A relatively homogeneous nonlinear area that differs from its surroundings. A
habitat feature isolated from other similar habitats.
Photodermatitis: A blistering condition of the skin in response to exposure to sunlight.
Raster Modelling: Evaluation of the landscape based on a grid approach, where each
pixel is assigned a value based on the degree to which it represents a series of
predefined criteria.
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Species at Risk: Species that have been defined as endangered, threatened, or
special concern by federal or provincial government.
Securement: In the context of conservation, a process to ensure legal protection such
as through ownership or agreement.
Succession: The process of ecosystem recovery after a disturbance, such as from
grassland to shrubland to forest.
Tallgrass: Native prairie or savanna habitat that is characterized by tall grasses.
Terrestrial: On or relating to the earth. Land dwelling as opposed to aquatic.
Vector Analysis: The assigning of values to polygons that represent habitat patches
based on the characteristics of the individual polygons and their relationship to each
other.
Watershed: The area of land that drains into a river, lake, or other water body.
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REFERENCES
Badzinski, D.S., R.W. Archer, S.T.A. Timmermans, K.E. Harrison, and K.E. Jones.
2008. Assessment of Trends in Frog and Toad Populations in Ontario Using Citizen
Science Monitoring Data. Bird Studies Canada and Environment Canada.
Bailey, R.O. and D.J. Reed. 2004. ALUS: The Farmer’s Conservation Plan: A
Proposal to Test and Alternative Land Use Services Project in Norfolk County. Norfolk
Federation of Agriculture.
Bakowsky, W. and J.L. Riley. 1992. A survey of the prairies and savannas of southern
Ontario. In Wickett, R.G., P.D. Lewis, A. Woodliffe and P. Pratt (eds.) Proceedings of
the Thirteenth North American Prairie Conference. Department of Parks and
Recreation, Windsor.
Beatley, T. 2011. Biophilic Cities: Integrating Nature into Urban Design and Planning.
Island Press, Washington DC.
Bell, A. 2010. Wind wars: How we can live with turbines without wrecking the
wilderness. OnNature Autumn 2010.
Bennett, A.F. 1999. Linkages in the Landscape: The Role of Corridors and
Connectivity in Wildlife Conservation. World Conservation Union, Gland, Switzerland.
Brittingham, M.C. and S.A. Temple. 1983. Have cowbirds caused forest songbirds to
decline? BioScience 33: 31-35.
Brownell, V.R. 1993. Waterfront Natural Areas Part 1: An Overview of Natural Areas
long the Lake Ontario Waterfront from Burlington to Trenton. Waterfront Regeneration
Trust.
Buttle, J.M. 1995. Channel changes following headwater reforestation: The Ganaraska
River, Ontario, Canada. Geographiska Annaler. Series A, Physical Geography, Vol. 77,
No. 3, 107-118.
Cappiella, K., T. Schueler, and T. Wright. 2005. Urban Watershed Forestry Manual,
Part 1: Methods for Increasing Forest Cover in a Watershed. United States Department
of Agriculture, Forest Service, Northeastern Area.
Catling, P.M., V.R. Catling, and S.M. McKay-Kuja. 1992. The extent, floristic
composition and maintenance of the Rice Lake Plains, Ontario, based on historical
records. Canadian Field Naturalist 106: 73-86.
Colburn, E.A. 2005. Vernal Pools: Natural History and Conservation. McDonald and
Woodward Books, Granville, Ohio.
82 | P a g e
Columbo, S.J., D.W. McKenney, K.M. Lawrence, and P.A. Gray. 2007. Climate
Change Projections for Ontario: Practical Information for Policymakers and Planners.
Climate Change Research Report CCRR-09, Applied Research and Development
Branch, Ontario Ministry of Natural Resources.
Collinge, S.K. 2009. Ecology of Fragmented Landscapes. Johns Hopkins University
Press, Baltimore.
Crooks, K.R. and M. Sanjayan (Eds.). 2006. Connectivity Conservation. Cambridge
University Press.
Ducks Unlimited Canada. 2010. Southern Ontario Wetland Conversion Analysis. Final
Report, March 2010.
Ecological Services for Planning. 1995. Using the Natural Heritage Strategy Approach
to Develop Habitat Rehabilitation and Restoration Targets and Project Priorities.
Ecological Services for Planning Limited, Guelph. 82 pp.
Environment Canada. 2004. How Much Habitat is Enough?: A Framework for Guiding
Habitat Rehabilitation in Great Lakes Areas of Concern. Second Edition. Minister of
Public Works and Government Services.
Environment Canada. 2007. Area Sensitive Birds in Urban Areas. Available at
www.on.ec.gc.ca/wildlife/publications-e.html
Environment Canada. 2010. Durham Coastal Wetland Monitoring Project 6-Year
Technical Report, Module 3 – Biological Condition. Environment Canada-Canadian
Wildlife Service.
Environment Canada. 2013. How Much Habitat is Enough? Third Edition.
Environment Canada, Toronto.
Environmental Law Institute. 2003. Conservation Thresholds for Land Use Planners.
Washington D.C.
Evergreen Foundation. 2001. Urban Naturalization in Canada: A Policy and Program
Guidebook. Evergreen Foundation, Toronto.
Forman, R.T.T. 1995. Land Mosaics: The Ecology of Landscapes and Regions.
Cambridge University Press.
Forman, R.T.T. and M. Godron. 1986. Landscape Ecology. John Wiley and Sons,
New York.
Forman, R.T.T., D. Sperling, J.A. Bissonette, A.P. Clevenger, C.D. Cutshall, V.H. Dale,
L. Fahrig, R. France, C.R., Goldman, K. Heanue, J.A. Jones, F.J. Swanson, T.
Turrentine, and T.C. Winter. 2003. Road Ecology: Science and Solution. Island Press,
Washington DC.
83 | P a g e
Fraser, G.S. and B.J.M. Stutchbury. 2004. Area sensitive forest birds move extensively
among forest patches. Biological Conservation 118(3): 377-387
Gibbs, J.P., A.R. Breisch, P.K. Ducey, G. Johnson, J.L. Behler, and R.C. Bothner. 2007.
The Amphibians and Reptiles of New York State. Oxford University Press, New York.
Goetz, S.J., R.K. Wright, A.J. Smith, E. Zinecker and E. Schaub. 2003. IKONOS
imagery for resource management: Tree cover, impervious surfaces, and riparian buffer
analyses in the mid-Atlantic region. Remote Sensing of Environment 88, Issues 1-2:
195-208.
Goldsmith, B. (Ed.). 1991. Monitoring for Conservation and Ecology. Chapman and
Hall, London.
Government of Canada. 2004. Invasive Alien Species Strategy for Canada.
Environment Canada.
Hanski, I., and D. Simberloff. 1997. The metapopulation approach, its history,
conceptual domain, and application to conservation. In Hanski and Gilpin 1997 5-26.
Hanski, I., and M. Gilpin (Eds.). 1997. Metapopulation Biology. Academic Press, San
Diego, CA.
Henry, M. and P. Quinby. 2010. Ontario’s Old-Growth Forests. Fitzhenry and
Whiteside, Marham, Ontario.
Hilts, S.D, M.D. Kirk, and R.A. Reid. 1986. Islands of Green: Natural Heritage
Protection in Ontario. Ontario Heritage Foundation, Toronto.
Hohnson, E.A. and M.W. Klemens. 2005. Nature in Fragments: The Legacy of Sprawl.
Columbia University Press, New York.
Holyoak, M., M.A. Leibold, and R.D. Holt (Eds.). 2005. Metacommunities: Spatial
Dynamics and Ecological Communities. University of Chicago Press, Chicago.
Hubbell, S.P. 2001. The Unified Neutral Theory of Biodiversity and Biogeography.
Princeton University Press, Princeton.
Johnson, E.A. and M.W. Klemens. 2005. Nature in Fragments: The Legacy of Urban
Sprawl. Columbia University Press, New York.
Kruger, K. No date. Habitat Fragmentation: Falling Apart at the Seams.
www.sustainableinfield.edublogs.org
Kurta, A. 1995. Mammals of the Great Lakes Region. Revised Edition. Fitzhenry and
Whiteside, Toronto.
Laine, A. (Ed.). 2008. Establishing Tree Cover. Best Management Practices
Agroforestry Series Volume 2. Service Ontario.
84 | P a g e
Larson, B.M., J.L. Riley, E.A. Snell, and H.G. Godschalk. 1999. The Woodland
Heritage of Southern Ontario. Federation of Ontario Naturalists, Toronto.
Lee, H.T., W.D. Bakowsky, J. Riley, J. Bowles, M. Puddister, P. Uhlig, and S. McMurray.
1998. Ecological Land Classification for Southern Ontario: First Approximation and its
Application. Ontario Ministry of Natural Resources, Southcentral Science Section,
Science Development and Transfer Branch. SCSS Field Guide FG-02.
Leitao, A.B., J. Miller, J. Ahern and K. McGarigal. 2006. Measuring Landscapes: A
Planner’s Handbook. Island Press, Washington D.C.
Levins, R. 1969. Some demographic and genetic consequences of environmental
heterogeneity for biological control. Bulletin of the Entomological Society of America 15:
237-240.
Little, C.E. 1995. Greenways for America. Johns Hopkins University Press, Baltimore.
Lovejoy, T., and L. Hannah. 2006. Climate Change and Biodiversity. Yale University
Press, New Haven, CT.
McCracken, J.D. 2005. Where the Bobolinks Roam: The Plight of North America’s
Grassland Birds. Biodiversity 6(3): 20-29.
Norris, D.R. and B.J.M. Stutchbury. 2001. Extraterritorial movements of a forest
songbird in a fragmented landscape. Conservation Biology 15(3): 729-736.
Noss, R.F. 1983. A regional approach to maintain diversity. BioScience 33: 700-7006.
Noss, R.F. 1992. The Wildlands Project land conservation strategy. Wild Earth
Special Issue: 10-24.
Noss, R.F. and L.D. Harris. 1990. Habitat connectivity and the conservation of
biological diversity: Florida as a case history. Pages 131-135 in Proceedings of the
1989 Society of American Foresters National Convention, Spokane WA. Society of
American Foresters, Bethesda, MA.
Noss, R.F. and A. Cooperrider. 1994. Saving Nature’s Legacy: Protecting and
Restoring Biodiversity. Island Press, Washington DC.
Ontario Biodiversity Council. 2011. Ontario’s Biodiversity Strategy: Protecting What
Sustains Us. Ontario Biodiversity Council, Peterborough, Ontario.
Ontario Ministry of Municipal Affairs and Housing. 2002. Oak Ridges Moraine
Conservation Plan. Queens Printer for Ontario.
Ontario Ministry of Municipal Affairs and Housing. 2005. Greenbelt Plan. Queens
Printer for Ontario.
85 | P a g e
Ontario Ministry of Natural Resources. 1992. A Natural Heritage Areas Strategy for
Ontario (draft). Ontario Ministry of Natural Resources Provincial Parks and Natural
Heritage Policy Branch.
Ontario Ministry of Natural Resources. 2000a. The Big Picture Project: developing a
natural heritage vision for Carolinian Canada. Natural Heritage Information Centre
Newsletter, Winter 2000.
Ontario Ministry of Natural Resources. 2000b. Significant Wildlife Habitat Technical
Guide. Queen’s Printer for Ontario.
Ontario Ministry of Natural Resources. 2005. Protecting What Sustains Us: Ontario’s
Biodiversity Strategy.
Ontario Ministry of Natural Resources. 2010. Natural Heritage Reference Manual for
Natural Heritage Policies of the Provincial Policy Statement, 2005. Queen’s Printer for
Ontario.
Pridham, D. 2009. A Landowner’s Guide to Controlling Invasive Woodland Plants.
Reznicek, A.A. 1983. Association of relict prairie flora with Indian trails in central
Ontario. In Brewer, R. (Ed.) Proceedings of the Eighth North American Prairie
Conference, Western Michigan University, Kalamazoo.
Rich, C. and T. Longcore (Eds.) 2006. Ecological Consequences of Artificial Night
Lighting. Island Press, Washington D.C.
Riley, J.L. and P. Mohr. 1994. The Natural Heritage of Southern Ontario’s Settled
Landscapes: A Review of Conservation and Restoration Ecology for Land-Use
Planning. Ontario Ministry of Natural Resources, Southern Region, Aurora, Ontario,
Science and Technology Transfer, Technical Report TR-001.
Richardson, A.H. 1944. The Ganaraska Watershed: A study in land use with
recommendations for the rehabilitation of the area in the post-war period. Ontario
Department of Planning and Development, Toronto, Ontario.
Rodger, L. 1998. Tallgrass Communities of Southern Ontario: A Recovery Plan. World
Wildlife Fund and Ontario Ministry of Natural Resources.
Rosenberg, D.K., B.R. Noon, and E.C. Meslow. 1997. Biological corridors: Form,
function and efficacy. BioScience 47: 677-687.
Root, T.L. and L. Hughes. 2005. Present and future phonological changes in wild
plants and animals. In Lovejoy, T.E. and L. Hannah (eds.). 2005. Climate Change and
Biodiversity. Yale University Press, New Haven.
Ross, C. 2010. Songs of the Bobolink. ON Nature 50(2): 24-29.
Sauer, L.J. 1998. The Once and Future Forest. Island Press, Washington DC.
86 | P a g e
Schaefer, V., H. Rudd, and J. Vala. 2004. Urban Biodiversity: Exploring Natural Habitat
and its Value in Cities. Captus Press, Vancouver.
Senanayake, R. and J.B. Jack. 1998. Analog Forestry: An Introduction. Monash
University Publications. Monash University, Clayton, Victoria, Australia.
Shiva, V. 1993. Monocultures of the Mind: Perspectives on Biodiversity and
Biotechnology. Zed Books, London.
Taylor, P.D, L. Fahrig, K Henein, and G. Merriam. 1993. Connectivity is a vital element
of landscape structure. Oikos 68: 571-573.
Terborgh, J., L. Lopez, P. Nunez, M. Rao, G. Shahabuddin, G. Orihuela, M. Riveros, R.
Ascanio, G.H. Adler, T.D. Lambert, and L. Balbas. 2001. Ecological meltdown in
predator-free forest fragments. Science 294: 1923-1926.
Tilman, D, J. Hill, and C. Lehman. 2006. Carbon-negative biofuels from low-input high-
diversity grassland biomass. Science 314: 1598-1600.
Toronto and Region Conservation Authority. 2004. Toronto and Region Terrestrial
Natural Heritage System Strategy.
Traill, C.P. 1885. Studies of Plant Life in Canada. A.S. Woodburn, Ottawa.
Varrin, R., J. Bowman, and P.A. Gray. 2007. The Known and Potential Impacts of
Climate Change on Biodiversity in Ontario’s Terrestrial Ecosystems: Case Studies and
Recommendations for Adaptation. Applied Research and Development Branch, Ontario
Ministry of Natural Resources.
Veysey, J.S., K.J. Babbitt, and A. Cooper. 2009. An experimental assessment of buffer
width: Implications for salamander migratory behavior. Biological Conservation 142(10):
2227-2239.
Villard, M.A. 1998. On forest-interior species, edge avoidance, area sensitivity and
dogmas in avian conservation. The Auk 115: 801-805.
Vitousek, P.M., C.M. D’Antonio, L.L. Loope, and R. Westbrooks. 1996. Biological
invasions as global environmental change. American Scientist 84: 468-478.
Wall, G. and C. Wright. 1977. The Environmental Impact of Outdoor Recreation.
Department of Geography Publication Series No. 11, University of Waterloo.
White, D.J. 2003. Prairie, Savannah, and Sand Barren Communities of Peterborough
District. Ontario Parks, Ontario Ministry of Natural Resources, Peterborough District.
Zuckerberg, B. and W.F. Porter. 2010. Thresholds in the long-term responses of
breeding birds to forest cover and fragmentation. Biological Conservation 143(4): 952-
962.
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APPENDIX 1
USING GIS TO DEFINE THE NATURAL HERITAGE SYSTEM
1. Landscape Analysis and the Natural Heritage System Model
The GRCA has adopted and adapted the approach developed by the Toronto and
Region Conservation Authority. This involves a vector landscape analysis of existing
habitat cover and characteristics of individual habitat patches, as well as a raster-based
model to demonstrate where there could be improvements. The existing conditions plus
the areas defined for improvements together become a “target” natural heritage system
that helps to prioritize stewardship and acquisition efforts and inform land use planning.
Once a target system is defined the vector landscape analysis is re-applied to
demonstrate and quantify the potential improvements in cover and habitat patch
characteristics.
2. Vector Landscape Analysis
This GIS analysis evaluates the geometric qualities of habitat patches and their
configuration in the landscape. As such, all patches and land use types are depicted as
polygons in the GIS environment. Fundamentally this works for fragmented landscapes
only. For example, a landscape or watershed that is composed of 100 percent forest
cover would contain a single habitat patch (which may even extend beyond the study
area), whereas a fragmented landscape contains patches, corridors, and the
surrounding matrix, each of which can be evaluated comparatively.
Prior to the analysis the Ontario Ministry of Natural Resources (MNR) Southern Ontario
Land Resource Information System (SOLRIS) vector-based woodland layer was
compared with the GRCA ELC product. This SOLRIS layer provides seamless forest
cover mapping across southern Ontario, making it easier to match natural heritage
systems that are based on forest cover across jurisdictional boundaries. Although it
included thickets and hedgerows, the SOLRIS layer proved to be very accurate, and was
therefore used as a reference for improving the accuracy of the ELC polygons which
GRCA had defined as forest.
The vector analysis requires that all defined land use types be classified as either urban
or agriculture, and all ELC community types be clumped into four major vegetation
types: forest, meadow, wetland, and beach/bluff. Once this is done, a figure of total
cover for each is calculated by study area or watershed. It is important to note that treed
swamps are counted as both wetlands and forests in this calculation, but are considered
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forest in other calculations used during both the vector and raster analysis. This being
the case, when stating what the total natural cover is for a study area, care must be
taken not to count the treed swamp cover twice. It is also important to note that the ELC
suggests mapping only communities 0.5 ha or larger. However, since open water
wetlands that are smaller than this can be vital breeding areas for amphibians, GRCA
has made an attempt to map these even when they are smaller than the suggested size
limit. The breakdown of clumped land use and ELC types is as follows:
*based on types known to exist in study area
The vector analysis involves scoring habitat patches using three criteria: patch size, patch shape, and matrix influence. Each of these is based on principles of conservation biology, as explained in detail below. In addition, a combined total score for size, shape and matrix influence is calculated for each patch. Each of these can be depicted on a map of the study area showing habitat patch polygons of different colours based on their score. For accuracy, when a habitat patch extends beyond the watershed boundary, values are calculated for the entire patch, not just the portion in watershed. The accuracy of the vector analysis is dependent upon the accuracy of the ELC
mapping. This in turn is based on factors such as date of air photos used, experience of
air photo interpreter, and parameters set for digitizing, such as minimum size of polygon
to be mapped and effort expended in mapping detail. In the case of the GRCA mapping,
a minimum size of 0.5 ha was used for mapping polygons, except for wetlands, in which
case there was no size limit. The accuracy target for polygon boundary detail was set at
approximately 5 metres, meaning that the canopy of large trees at the edges of habitat
patches would be reflected in the shape.
The vector analysis used a script developed by TRCA for ArcView 3.2 software.
Because GRCA is currently using Arc GIS 10.1, this necessitated adapting from an
Avenue to a Python script for compatibility with the newer software. What follows is a
detailed description of each measure used in the vector analysis, and a rationale.
Major Habitat Type or Land Use
ELC and Land Use Types Included*
Forest FOD, FOC, FOM, SWD, SWC, SWM, CUP, CUW
Meadow CUM, CUT, CUS, TPO, TPS, TPW, SBO, SBS, SBT
Wetland SWD, SWC, SWM, SWT, MAM, MAS, SAS, SAM, SAF, BOO, BOS, BOT, FEO, FES, FET
Beach/Bluff BBO, BBS, BBT, BLO, BLS, BLT
Agriculture IAG (intensive agriculture), NAG (non-intensive agriculture)
Urban U (urban development), RD (rural development), MOS (manicured open space), aggregate, roads, railways
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2.1 Patch Size
This is based on the general principle that “bigger is better.” Larger patches receive a
higher score than smaller patches.
In general, wetlands, particularly open water wetlands, are naturally smaller than forests.
Many very small wetlands play a critical role in supporting populations of specialist
species such as amphibians. Accordingly, the size score for wetlands is based on
smaller units.
The scoring for forests and wetlands is as follows:
Forest Size (ha)
Wetland Size (ha)
Score
>0 <1 1
≥2 ≥1 2
≥10 ≥3 3
≥50 ≥10 4
≥250 ≥20 5
2.2 Patch Shape
This measure attempts to incorporate issues related to forest interior habitat as well as
the negative edge effects that can be harmful to forest ecosystems. The more compact
and less convoluted or perforated at patch is, the higher the score.
Patch shape is measured using a simple perimeter (edge)-to-area ratio (P/A). To
compensate for the increase in perimeter that comes with increasing size, a corrected
shape calculation is used (0.282 x Perimeter)/(Area)½ (Baker 1997). The minimum
perimeter-to-area ratio, and thus the most desirable shape for reducing exposure, is
found in a perfect circle. The scoring for shape is as follows:
Value (P/A) Score
≥500 1
≥300 2
≥200 3
≥125 4
≥100 5
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2.3 Matrix Influence This is a rough measure of the positive or negative influences in the landscape matrix surrounding a habitat patch. Assumptions behind the measure include: 1) urban areas generally have a negative influence on natural areas (noise, pollutants, recreational pressures, invasive plants, collecting, pets, roads, and barriers to movement); 2) natural areas generally have a positive influence on other natural areas (recruitment for populations, sources of food and shelter); and agricultural areas can have either positive or negative impacts on natural areas (allow movement of species, but can result in enrichment from fertilizers, or drift from pesticides). The matrix influence calculation considers the amount of urban, agricultural and natural cover within a two-kilometer radius of the outside edge of each habitat patch. In order to avoid data gaps in the radius area, the measure requires the definition and consideration of all ELC and land use types to at least 2 km from the outside edge of the watershed or study area. The outside edge was chosen over a center point for two reasons. First, in the case of very large patches, at 2 km from the center the influence of the patch on itself might be measured, rendering the calculation meaningless. Secondly, the goal is to evaluate the outside forces impacting the patch in question, in essence positive or negative edge effects. A base point value of 1 point for natural, O points for agricultural, and – 1 for urban is used to reflect a positive, benign, or negative matrix influence. The percent of each of these land cover types is measured within the 2 km matrix, and each is multiplied by the base point value. From a biodiversity conservation perspective, the perfect patch surroundings would be 100 percent natural (e.g. a wetland within an extensive forest patch), and would receive a matrix score of 100, while the lowest possible score is –100 for a natural habitat patch completely surrounded by urban land use. The matrix influence score is as follows:
Matrix Score
-1 to -60 1
< - 20 2
-20 to +20 3
> +20 4
+60 to 100 5
2.4 Total Score
The total score is calculated through a weighted average of the scores for size, shape
and matrix influence. Of the three scored criteria, size is the single most important patch
attribute, both because large patches are more likely to maintain their functional integrity,
and because negative edge effects (related to shape and matrix influence) tend to have
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less influence on large patches. Therefore when adding results for the three criteria,
size is given an additional weighting on a sliding scale from small to large patches.
Note: a multiplier of 3 is used in the calculation of Total Score. For example, for a forest patch with the following scores: size = 5; shape = 3; and matrix = 4, the following equation would be used to calculate the total: 5(50%)*3 = 3(25%)*3 = 4(25%)*3 = 12.75. The weighting system for Total Score for forest and meadow and beach/bluff habitats is as follows:
Size (ha) % Size % Shape % Matrix
> 0 40% 30% 30%
≥ 10 45% 27.5% 27.5%
≥ 250 50% 25% 25%
≥ 500 55% 22.5% 22.5%
≥ 1000 65% 17.5% 17.5%
≥ 2000 75% 12.5% 12.5%
The weighting system for Total Score for wetlands is as follows:
Size (ha) % Size % Shape % Matrix
≥ 1 33.3% 33.3% 33.3%
≥ 3 40% 30% 30%
≥ 10 45% 27.5% 27.5%
≥ 20 50% 25% 25%
3. Value Surface Raster Model
The GIS raster model is used to identify opportunities for improving natural heritage
values in order to define a target natural heritage system. The ELC and land use
polygons used for the vector model form the basis of the model. They are transformed
into 10 x 10 metre pixels, each of which receives a value based on a number of set
natural heritage criteria. The criteria correspond to conditions in the landscape that
promote or retard biodiversity and ecological function. Through this process the entire
study area becomes a “value surface” made up of tiny pixels, each of which has a
numerical value and corresponding shade of colour based on how it scored. Thus the
natural heritage values are easily displayed with a range of shades from light to dark
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representing poor to excellent. The criteria used in the model, and an explanation of
their relevance follows:
3.1 Patch Quality (Total Vector Score)
This criterion is based on the total weighted score received by a habitat patch for size,
shape, and matrix influence in the vector landscape analysis. Thus every habitat patch
gets a base value higher than the surrounding landscape, based on its existing
characteristics and landscape context. The assumption is that the higher the total score
is for a patch, the more valuable it is for the target natural heritage system. Total scores
are translated from the raw vector score (on a scale of 1-15) to a raw raster shape score
(on a scale of 1-10).
Raw Score Total Score
0-1.5 1
1.5-3 2
3-4.5 3
4.5-6 4
6-7.5 5
7.5-9 6
9-10.5 7
10.5-12 8
12-13.5 9
13.5-15 10
3.2 Forest Interior
The importance of forest interior is described in the discussion of patch shape above.
The most commonly accepted distance from an edge that defines where edge habitat
(with its associated negative impacts) ends and interior habitat begins, is 100 m
(Environment Canada 2006). Therefore, for this calculation an interior patch buffer of
100 m is used, and every pixel that falls inside this area (100 m or more from the inside
of the edge of a forest patch) automatically gets 10 points. Since there can be no
interior without the buffer surrounding it, all patches within the 100 m buffer itself also get
10 points. All other pixels in the surrounding landscape receive zero points.
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Distance from Edge (m) Score
< 100 10
≥ 100 10
3.3 Distance from Urban Areas
This criterion assumes that the further away a natural area is from an urban area, the
better, because of all the negative external influences described under Patch Shape and
Matrix Influence in the vector landscape analysis. The maximum value of 10 points is
based on a distance of 2 km, the same distance considered in the Matrix Influence
calculation. By placing a higher value on pixels that are far from urban areas, those
lands are more likely to be selected as part of the natural heritage system, either as
existing or potential habitat.
Distance (metres) Score
0-10 1
10-30 2
30-60 3
60-120 4
120-200 5
200-300 6
300-500 7
500-1000 8
1000-2000 9
2000 + 10
3.4 Distance from Roads
Roads have many negative impacts on wildlife and natural areas. They act as barriers
to movement of some species, and result in road kill for many individuals of other
species. Although it is easy to see their impact on medium to large sized mammals,
what is invisible to drivers as they speed through the landscape are the hundreds of
amphibians and reptiles that have been killed on the roads. Many insects are killed by
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automobiles, as a look at the grill of any car can demonstrate. This measure assumes
that the further a natural area is from a road, the better, up to a distance of 1 km. All
roads outside of urban areas are considered.
Distance (metres) Score
0-100 1
100-200 2
200-300 3
300-400 4
400-500 5
500-600 6
600-700 7
700-800 8
800-900 9
900 + 10
Note - TRCA table has gap from 900-1000. Consider adding a zero points for 0-100
3.5 Proximity to Natural Areas
Natural areas for this calculation include any ELC community type, including cultural
communities and open water. They do not include human land use areas such as
urban, agriculture, and aggregate pits (if the latter supports vegetation it would be a
cultural ELC community).
This values pixels based on their proximity to a natural area. The highest values go to
existing natural areas, with values decreasing the further the pixel is from any existing
natural area up to a distance of 2 km. Pixels between two habitat patches would score
more than those found equal distance from a single patch. This measure assumes that
patches in close proximity to other patches provide a supporting function for those
species with the capacity to move between them. In this sense it is one of several
measures that incorporate connectivity into the natural heritage system design.
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Distance (metres) Score
0-10 10
10-30 9
30-60 8
60-120 7
120-200 6
200-300 5
300-500 4
500-1000 3
1000-2000 2
2000 + 1
3.6 Proximity of a Wetland to a Forest
This measure considers the needs of many species to have both forests and wetlands in
close proximity for survival. In particular it considers the needs of amphibians such as
wood frog, spring peeper, eastern newt and the mole salamanders (Ambystoma), all of
which live in upland forests and annually migrate to wetlands in order to breed.
For this measure, SWM, SWD, and SWC are considered to be forest rather than
wetland, otherwise their proximity would be zero. Furthermore, their total scores would
be overly inflated because they would be scored for all of both forest and wetland related
measures.
The maximum distance used for this calculation is 2000 m. This is the distance used in
the matrix influence calculation and it is also approximately the width of a concession,
where the defining roads represent hazards or barriers to the migration of these species.
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Distance (metres)
Score
0-10 10
10-30 9
30-60 8
60-120 7
120-200 6
200-300 5
300-500 4
500-1000 3
1000-2000 2
2000 + 1
3.7 Proximity of a Forest to a Wetland
This layer is the inverse of the previous. It values forest that is immediately adjacent to
wetlands, the justification being that for a species that uses both habitat types, the
proximity of the forest from the wetland is as important as the proximity of the wetland to
the forest. The score breakdown is also the same as for the previous measure.
For this measure, SWM, SWD, and SWC are considered to be forest rather than
wetland, otherwise their proximity would be zero. Furthermore, their total scores would
be overly inflated because they would be scored for all of both forest and wetland related
measures.
Distance (metres)
Score
0-10 10
10-30 9
30-60 8
60-120 7
120-200 6
200-300 5
300-500 4
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Distance (metres)
Score
500-1000 3
1000-2000 2
2000 + 1
3.8 Proximity to a Watercourse
For this measure “watercourse” includes streams and open water bodies. The latter
consists of all OAO polygons as well as major lakes.
This measure recognizes that many species use both upland and open water habitats,
and that a water source is import for drinking. There is also an important nutrient
exchange between aquatic and terrestrial ecosystems. Finally, by using a buffer the
measure recognizes the many values of riparian habitats for aquatic ecosystems and
their support for connectivity in fragmented, human-dominated landscapes. This
measure helps to build connectivity into natural heritage systems by identifying potential
areas for riparian cover that also can increase corridor function. The criterion and
scoring has been modified from the TRCA approach, which separates proximity to a
watercourse with and without a fill line.
Distance (metres) Score
0-30 10
30-50 9
50-70 8
70-90 7
90-110 6
110-130 5
130-150 4
150-170 3
170-190 2
190-210 1
> 210 0
Notes on data use for the value surface model
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3.9 Proximity to Lake Ontario
Lake Ontario and other large bodies of water represent a substantial challenge to
migratory birds and butterflies. On their autumn journey south, migrants – especially
delicate Monarch butterflies – must wait until the optimal weather conditions occur for
them to cross such an expanse of open water. On the return journey in the spring
migrant birds, having crossed the lake, will seek food, shelter, and an opportunity to rest.
In particular, those birds that would have begun their flight several hundred kilometers
south of the lake are more likely to be exhausted once they have crossed, and may
quickly land in any suitable habitat. For this reason natural areas that are close to the
lake are particularly valuable as staging and resting areas for migrants, and as such
provide an important contribution towards sustaining this important ecological
phenomenon.
The Significant Wildlife Habitat Technical Manual suggests that sites within 5 km of the
Lake Ontario and Lake Erie shorelines will be most significant as stopover areas and
further notes that “many of the best sites are found within 2 km of Lake Ontario and Lake
Erie” (OMNR 2000). Therefore, in order to capture this value in the natural heritage
system model all natural habitat types within 2 km of the Lake Ontario shoreline receive
an additional 10 points.
4. Defining a Target Natural Heritage System
A target natural heritage system is defined by using the total of all the criteria values in
the raster value surface analysis. Essentially, every pixel across the entire landscape
has a value based on how that part of the landscape meets the natural heritage criteria.
These values can be depicted on a map using various shades of a single colour, with
low values being lighter and high values being darker. The result is the “value surface”
where large habitat patches in close proximity within rural areas will tend to have darker
shades (higher values) than smaller isolated patches that are closer to urban areas.
Lighter colours (lowest values) will appear in actual urbanized areas (Figure 1).
It is important to note that the higher values may not always be in areas where there are
existing natural features. For example it is possible that a group of pixels in what is
actually an agricultural area could receive exceptionally high values for several criteria
such as distance from roads, distance from urban, and proximity to natural areas. This
would be an area where habitat could have high value if it existed here, thus is an area
to be considered for restoration potential.
Once the value surface is created, a mechanism is necessary by which a line can be
drawn to define the target natural heritage system. One way to do this is simply to
impose a pre-determined target for natural cover. For example, 30 percent forest cover
has been widely promoted as a minimum standard (Environment Canada 2006). If the
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watershed or study area currently contains less than this amount, then the point at which
the total pixel values would correspond to 30 percent cover can be determined by
manipulating the histogram that appears when “Display Values” is selected in the GIS
software. When this value is selected all pixels with values that would add up to 30
percent are selected. Those areas of corresponding lands that are not already natural
cover become the potential natural heritage areas, and these, combined with the existing
natural features identified in the process together become the “target” natural heritage
system. This exercise can be undertaken for any predetermined cover target.
Figure 1. GRCA watershed “value surface” results from raster analysis.
If the watershed or study area already contains more than the recommended minimum
target this should not be interpreted as evidence that habitat loss is an option. The 30
percent forest cover recommendation is a minimum, and is based on studies
demonstrating that most species of a select group of organisms (e.g. birds) that are
associated with the habitat type will be represented at this threshold. To ensure good
ecological function and the representation of all native species, considerably more than
30 percent cover will be required. The exact amount depends on many variables related
to the quality of habitat, how well connected it is, and what the surrounding landscape
matrix is composed of. The main point being that there is always room for improvement,
and that a threshold can be selected that demonstrates this.
A second approach is to set a pre-determined acceptable percent cover increment, for
example, five or ten percent more than what currently exists. The line around the target
system can then be based on selecting existing habitat plus all of the higher scoring
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pixils out to the point at which the additional target percent cover is achieved. The
vector landscape analysis is then run on the result to demonstrate improvements. Using
this approach the target system is based on what is considered acceptable, not on a
threshold in the data. Nevertheless, since the science demonstrates a minimum of 30
percent forest cover, and the landscape already contains more than this amount, then
one can argue that what is desirable according to the science is in fact incorporated in
the system, and therefore that an increase in cover based on a political decision of what
is acceptable should be justified.
A third, and more time consuming approach, is to use a number of potential habitat
increments and run the vector landscape analysis on the results for each of these. A
histogram illustrating the results for all of these can then be generated to determine if a
point exists where there is an obvious threshold in the landscape values that can then be
selected as a target.
A fourth approach is to use GIS to create a histogram based on the total raster values
using natural breaks (Jenks) in the data (Figure 2). This graph is based on the total
range of values and the number of pixels occurring within each of these. One then
determines where in the graph the current percent natural cover conditions occur
(highlighted in blue), in this case approximately 32 percent cover. In general the values
to the right of this selected bar represent existing habitat because they have received the
highest ecological values per pixel. The bars to the left represent the remainder of the
landscape (where clearly the majority of pixels received a low score). Each of these in
turn can be viewed as an increment toward improving the natural heritage system by
adding potential habitat cover. Although these values are progressively lower as one
moves left, each can be considered the next best scenario for improvement. One then
selects a bar in the graph that corresponds to an obvious peak in the number of pixels
that will also lead to an acceptable increase in percent cover. Since no “correct” or best
ecological scenario can be defined (true best would likely be 100 percent natural), this
approach attempts to add a non-biased element to the inevitable political decision about
how much habitat is acceptable, given other land use demands. More than one
increment can be selected to have interim and long-term target scenarios.
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ELC Final Raster Histogram
Final Raster Score
706560555045403530252015105
Nu
mb
er
Ce
lls (
25
m²
/ ce
ll)
1,300,000
1,200,000
1,100,000
1,000,000
900,000
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
Figure 2. Histogram of raster values with existing natural cover highlighted in blue.
For this Strategy there were no obvious spikes in the graph, therefore each bar was
selected individually and the corresponding natural heritage system target displayed and
assessed for obvious improvements, particularly in habitat connectivity. Two target
scenarios were selected using the histogram, one which would represent an increase
from 32 to 40.4 percent cover (Figures 3 and 4), and the second to 50.9 percent cover
(Figures 5 and 6). These target scenarios correspond well with the revised How Much
Habitat Is Enough? federal guidelines for forest cover, which suggest that 30 percent
should be a minimum and is a high risk approach, 40 percent is a medium risk approach,
and 50 percent is a low risk approach for maintaining ecological integrity and water
quality (Environment Canada 2013).
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ELC Final Raster Histogram
Final Raster Score
706560555045403530252015105
Nu
mb
er
Ce
lls (
25
m²
/ ce
ll)
1,300,000
1,200,000
1,100,000
1,000,000
900,000
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
Figure 3. Histogram showing range of raster values, with Bar 29 selected resulting in 40.4 percent natural
cover.
Figure 4. GRCA watershed showing existing natural cover (green) and 40.4 percent target (red).
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ELC Final Raster Histogram
Final Raster Score
706560555045403530252015105
Nu
mb
er
Ce
lls (
25
m²
/ ce
ll)
1,300,000
1,200,000
1,100,000
1,000,000
900,000
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
Figure 5. Histogram of raster values showing Bar 25 selected resulting in 50.9 percent natural cover.
Figure 6. GRCA watershed showing existing natural cover (green) and 50.9 percent target (red).
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The raster data is converted back to vector polygons using the GIS polygon smoothing
option Polynomial Approximation with Exponential Kernal (PAEK), which runs a line
roughly through the mid point of the jagged edged raster boundary. Specifically this was
done using a 100 metre tolerance. These are overlaid with the existing mapping of the
major habitat types (forest, wetland, meadow) that was used for the original vector
landscape analysis. If some existing natural areas fall outside of the target natural
heritage system they should not be considered worthless. They are part of the
supporting values in the matrix, and should therefore be identified as supporting habitat
for the natural heritage system, or they can simply be added to the system.
NHS target scenarios include small bodies of open water, and occasionally bleed into
urban areas. Because the intent is to define a terrestrial natural heritage system, the
potential habitat areas are supposed to be terrestrial only. Furthermore, the potential
habitat areas should only include agricultural lands and cultural meadow. Therefore,
using GIS the OAO and URB polygons in the ELC that are coincident with the target
system areas must be selected and erased from the target systems polygon layer prior
to running the vector landscape analysis. This can be accomplished by first running an
attribute query on the ELC layer to select all OAO and URB polygons followed by a
spatial query that selects only those that intersect the target system areas. Next, clip the
query results to the target systems vector layers. This effectively isolates only the OAO
and URB areas that are contained within the target system areas. The clipped layer is
then erased from the target systems layer. This results in a target system layer that
includes only those areas acceptable for the terrestrial natural heritage system.
One additional cleaning step was undertaken with the GIS. The target scenarios include
many very small isolated areas, some of which appear in the middle of open fields, and
many of which would simply be impractical or superfluous as restoration sites. As a
result, all such areas that were under 0.5 ha were systematically removed.
Once converted to polygons, the target areas are merged with existing habitat areas to
create a single layer, upon which the vector landscape analysis is re-run. The road layer
must be re-applied to ensure that habitat patches are defined where appropriate by
these features. Road width is based on a 30m right-of-way (15m on each side of the
centre line) for all roads except 400 series highways, for which this width is doubled.
The results for size, shape, matrix influence, and total score will for the most part reflect
the improvements represented by the areas targeted for restoration, should they be
planted. Roads must be clipped from the target system before this analysis is
undertaken. Actual figures comparing before and after results for each criteria are useful
for interpretation and marketing the concept of the improved natural heritage system.
Given that the historically dominant natural cover in the GRCA jurisdiction was forest,
then tree planting is generally what should be advocated for the areas identified as
having potential to improve the natural heritage system. There is a fundamental bias
towards forest cover in the model through the shape and forest interior, however this
does not suggest that only forest should be considered for restoration. Those areas with
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poorly drained soils may have potential to increase wetland cover (although the
dominant historical wetland type would have been swamp, which is equivalent to forest
in the model). Lands close to known tallgrass remnants may have potential to increase
prairie or savanna habitat if they are on well-drained sandy soils.
It is important to emphasize that the natural heritage system targets are conceptual and
long term. They can help prioritize areas for landowner contact to determine if there is
interest in stewardship work that would help meet the target. Actual achievement of the
target system, were it possible, would take decades. Some lands simply will not become
available, and there would undoubtedly be cases where restoration “banking” is
necessary in order to exchange some potential areas within the preferred target system
for those that are not. Policies in relation to the target system must be developed in
consultation with municipal partners. The vector landscape analysis results can be used
to quantify the trade-offs.
The restoration potential areas defined by the modeling are fundamentally based on
forest cover improvements. Two main factors determine this. First, the vector model
measures of shape and forest interior are expressions of forest-based conservation
principles. Second, the areas that are considered to have restoration potential are
agriculture and cultural meadow, both of which are terrestrial, and therefore not
immediately conducive to wetland restoration, for example.
To determine wetland restoration potential, assuming this means expanding existing or
creating new wetlands, would require a separate analysis based primarily on soil
permeability. Soil type data can further be overlaid with any available historical wetlands
mapping to help determine where wetland potential might be found. However, it should
be taken into consideration that where wetlands can exist now, without site alteration,
they already do exist. This is in contrast to forest, which was historically the dominant
ecosystem, and which most of the landscape would return to if left alone, without
intervention.
Tallgrass prairie and savanna are also not considered in the modeling. The OMNR has
a mapping layer of historical tallgrass communities. These rare community types should
be identified as not having forest restoration potential. This can be done either by
discouraging the model from identifying them as restoration potential areas (by giving
them a negative score, such as minus 10), or by overlaying the tallgrass mapping on the
target natural heritage system and identifying these as significant features or special
management areas. The former is the preferred approach because open tallgrass
habitat will not conflict with the forest targets dictated by the model. Because of this
conflict it is recommended that tallgrass restoration targets be set in areas that have
sandy soils and where tallgrass was known to exist historically, but that lie outside of the
target natural heritage system. These would then supplement the system.
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5. Using Landscape Metrics as Surrogate Measures of Ecological Health
The landscape vector analysis uses size, shape, and matrix influence measures.
Calculating the mean of each of these provides some indication of the ecological health
of habitat patches. When applied to both existing and modeled conditions these can
demonstrate before and after values. In addition to these, there are some other simple
and relevant measures used in landscape ecology can be applied to before and after
conditions. These are discussed below.
Percentage of Landscape, also known as Class Area Proportion simply measures the
percent of a given landscape (such as a watershed) that is covered by each habitat type
or land use. This can be used at a landscape scale to measure the amount of major
habitat types such as forest or wetland, and major land uses such as urban or
agriculture, or it can be used to measure the percent cover of any particular vegetation
community type or particular land use. A pie chart is a suitable format for graphically
demonstrating the proportion of habitat and land use classes in a given area.
Mean Patch Size is the average size of patches of a given habitat or land use type. This
measure, while applicable to all habitat types, is particularly valuable for forest in the
GRCA area. This is because under natural (i.e. pre-settlement conditions) forest was
the landscape matrix, and seldom occurred in patches. In contrast, wetlands, prairies,
bluffs etc., were not dominant, and therefore are “patchy” by nature. Increases in mean
patch size suggest a higher potential to support more species, more viable populations,
and more ecological functions.
Mean Patch Shape for the purposes of the GRCA, is the average score for the shape
value of habitat patches in the vector landscape analysis. In other words the mean
score for the perimeter-to-area ratio, rather than the ratio value itself. High mean values
for forest patches suggest less edge and more interior habitat.
Mean Patch Matrix Influence is simply the average score for the vector matrix influence
measure. High values suggest a relatively natural landscape with little negative external
influences on habitat patches. In contrast, low values suggest less natural cover and
more intense land use, in particular urban use, with associated negative impacts on
habitat patches.
Patch Number is the total number of patches, in this case of natural habitat. High
numbers of habitat patches suggest high levels of habitat fragmentation. Conversely,
low numbers of patches suggests less fragmentation, larger patches, and greater
connectivity of habitat in the landscape.
Contagion. In contrast to the above measures, which are vector-based, contagion is a
raster-based landscape metric. It measures the degree to which different habitats and
land uses are clumped in the landscape. Contagion computes the number and types of
land cover types in adjacent cells within a grid. A landscape where natural habitats are
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clumped suggests larger patches, higher connectivity, and less negative matrix
influence.
Road Density is a ratio measure of the total length of roads per area of a given
landscape. Roads have many negative impacts, among them reduction of wildlife
populations due to road kills and acting as barriers to the movement of many species.
Obviously a higher density of roads suggests a higher level of such impacts, thus less
ecological health of natural areas in the landscape.
It is important to keep in mind that all of these metrics are surrogate measures because
they are in fact only measuring polygons that represent the land cover conditions in the
real world, not the patches themselves. Landscape measures relate to species
presence or absence and ecological interactions and were developed based on
empirical field studies. However, although they can act as indicators of likely conditions
on the ground, they are not meant to be representative of actual conditions, nor can they
be accurate predictors. Only field studies of the patches themselves in a given context
can provide real-world data. More correlative studies of field data with landscape
metrics are required to validate the landscape metrics.
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APPENDIX 2 – ACRONYMS
ALUS
ANSI
ARCC
BFS
CFIA
COSEWIC
COSSARO
ELC
GIS
GRCA
MMAH
MMP
NHIC
OMAFRA
OMNR
OREG
PPS
PSW
SAR
SOLRIS
TRCA
UTM
Alternative Land Use Services
Area of Natural or Scientific Interest
Amphibian Road Call Count
Backyard Frog Survey
Canadian Food Inspection Agency
Committee on the Status of Endangered Wildlife in Canada
Committee on the Status of Species at Risk in Ontario
Ecological Land Classification System
Geographic Information Systems
Ganaraska Region Conservation Authority
Ontario Municipal Affairs and Housing
Marsh Monitoring Program
Natural Heritage Information Centre
Ontario Ministry of Agriculture, Food, and Rural Affairs
Ontario Ministry of Natural Resources
Ontario Road Ecology Group
Provincial Policy Statement
Provincially Significant Wetland
Species at Risk
Southern Ontario Land Resource Information System
Toronto and Region Conservation Authority
Universal Trans-Mercator mapping system
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PLACE PHOTO HERE,
OTHERWISE DELETE BOX
Month Day Year
Month Day Year
Ganaraska Region Conservation Authority
Ken Towle
Terrestrial Ecologist
2216 County Road 28
Port Hope, ON L1A 3V8
www.grca.on.ca
P: 905.885.8173
F: 905.885.9824
Month Day Year
