Habitat Loss, Degradation, and Fragmentation

Habitat Conversion/Transformation – change in habitat, can result in degradation or loss; conversion often implies loss

•Habitat Degradation – decline in habitat quality, affects many but not all species, may be temporary; Primary cause of species extinction globally and in most countries

•Habitat Loss – habitat changed in way that usually adversely affects most or all species, effects longer term

83% of Earth’s surface has been transformed by humans

60% ecosystems are considered degraded or unsustainably used

Here in particular we see the historical (pre-1500) loss of Mediterranean ecosystems, European, and eastern Asian forests as the first civilizations and empires had major impacts in these areas. We can’t lose much more habitat here since most is already heavily degraded from past and current use!

Notice that the predicted future loss of habitat is greatest in the tropical areas, particularly forests and drier arable lands (e.g. grasslands and savannas), but also in the taiga and coniferous forests of Canada and Russia

Only 42% of native veg cover remains in U.S.

FL, CA, and HI have greatest # of threatened ecosystems in U.S.

General Ecosystems: Habitat Loss and Degradation

Importance of Forests • What ecosystem services do forests provide? • Over 2/3 of all water supplies originate from or course

through and are influenced by forests • water filtration, cycling, flow rates • flood control • structural habitat for numerous species • fuel, fiber, other material products • climate regulation at various spatial scales • soil erosion control, enrich soils via organic matter

Deforestation • 50% global loss in past 300 years

• 29 countries > 90% loss

• 25 countries complete loss

• Europe least forested

• Africa highest current rate of loss

• ~1/25 humans practice slash and burn of forests

• 60% loss in tropics

• At current rate of loss, Amazon rain forest will vanish by 2030, and all tropical rain forests will be gone by 2090

Bolivia (1,098,581) 90,000 45,000 1,500 (2.1%)

Brazil (8,511,960) 2,860,000 1,800,000 50,000 (2.3%)

C. America (522,915) 500,000 55,000 3,300 (3.7%)

Columbia (1,138,891) 700,000 180,000 6,500 (2.3%)

Congo (342,000) 100,000 80,000 700 (.8%)

Ecuador (270,670) 132,000 44,000 3,000 (4.0%)

Indonesia (1,919,300) 1,220,000 530,000 12,000 (1.4%)

Cote D'Ivoire (322,463) 160,000 4,000 2,500 (15.6%)

Laos (236,800) 110,000 25,000 1,000 (1.5%)

Madagascar (590,992) 62,000 10,000 2,000 (8.3%)

Mexico (1,967,180) 400,000 110,000 7,000 (4.2%)

Nigeria (924,000) 72,000 10,000 4,000 (14.3%)

Philippines (299,400) 250,000 8,000 2,700 (5.4%)

Thailand (513,517) 435,000 22,000 6,000 (8.4%)

Historical Remains Annual % Loss) RF LOSS (cont)

http://upload.wikimedia.org/wikipedia/commons/7/7f/Oldgrowth3.jpg

KY Forests

• cover 47% state

• 2nd most biodiverse hardwood forests in U.S.

• 2nd leading hardwood producer

• 89% forest privately owned

Agriculture is primary land use that leads to habitat degradation; crop use intensity usually dictates impacts on biodiversity

Other Types of Forest Loss: Surface Mining creates massive swaths of habitat loss and fragmentation in the deciduous forests of Central Appalachia.

Southeastern KY, Southwestern West Virginia and Virginia illustrating the landscape-scale habitat loss and fragmentation of the eastern deciduous forest ecosystem by surface mining for coal (gray areas). You can literally see these from space. Some mines are tens of thousands of acres in size, and nearly 50% of some counties in Kentucky have been mined.

http://indiancountrytodaymedianetwork.com/photogallery/athabasca-oil-sands-in-all-their-terrible-glory/# http://www.youtube.com/watch?v=oYML36YbXo8 (60 Minutes; Background Info) http://www.youtube.com/watch?v=YkwoRivP17A (Indy video on impacts)

Alberta Tar Sands: Landscape scale loss and fragmentation of the boreal forest and wetlands of Canada to squeeze oil from tar Note: One recent study estimated that Canada's oil sands emits about 5 percent to 15 percent more carbon

dioxide, over the "well-to-wheels" lifetime analysis of the fuel, than average crude oil.

Grasslands • Cover ~ 41% of land surface • Grasslands are ecosystems that are dominated by

herbaceous vegetation, primarily grasses, but often have some minor shrub and tree components – they do not grow into forest or woodland as a result of climatic or other factors

• Maintained by drought, fire, grazing, freezing • In U.S. ~97% tallgrass prairie and ~60% shortgrass

prairie lost primarily to ag and urbanization

Urbanization

In KY…

•130 acres/day

• 48,000 acres/year

• 3rd per capita dev.

• “Golden Triangle” (LEX-LOU-CINCY)

• loss of 8% farmland past 30 years

Urbanization in central Kentucky (Lexington in center; green is forest, yellow = agriculture; gray = urban)

Habitat Fragmentation (Dealing with scattered bits and pieces)

• What is habitat fragmentation? break into smaller pieces • 2 components: reduction in area, and reconfiguration into

smaller pieces • Habitat fragmentation vs. Habitat shredding

The Fragmentation Process (Terrestrial Systems)

Habitat Patch

HabitatMatrix

Patch, Landscape Matrix

Lexington’s forest “islands” in a sea of urbanization

Fragmentation and Heterogeneity

• Natural disturbances create heterogeneity beyond that generated by physical environment, a pattern referred to as a space-time or shifting mosaic.

• Some landscapes inherently more patchy than others • Patchiness leads to habitat quality variation which in turn

leads to differences in species abundance and distribution at several spatial (space) and temporal (time) scales.

Spatial scales of Habitat Fragmentation: Can be

measured at very large to very small scales

Continental

Local

Stand-level

Disturbance Events and

Habitat Heterogeneity

Natural Patchiness vs. Fragmentation (some generalizations)

• Fragmentation typically leads to reduction of habitat connectivity and extent – species may/not adjust

• Fragmented landscapes often have more features such as roads deleterious to biodiversity

• Naturally patchy areas typically have rich internal patch structure, whereas fragmented landscapes are usually more simplified

• Naturally patchy areas typically have less contrast (structural differences) between adjacent patches, whereas fragmented landscapes usually have more. More contrast usually causes more pronounced edge effects (influences created at the boundary between habitats)

• Fragmented landscapes in summary create conditions by which species have not typically evolutionarily adapted

Habitat Contrast

• You can think of the “good” habitat patches as potentially inhabitable islands that animals and plants can move to and establish in. The “island/habitat patch hopping” or colonization capacity of an organism is strongly influenced by the distance between patches, and the likelihood the organism will remain there and not go extinct is strongly influenced by the size and quality of the patch. Sound familiar (island biogeographic concept)?

Fragmentation and natural heterogeneity causes most species to occur as sets of local populations spatially isolated (at different scales), but connected via occasional dispersal. These are called metapopulations.

Patch A Patch B

Bighorn Sheep Navigation of the Sky Islands of SE Arizona

Metapopulation Dynamics

Population Source = usually consists of individuals in good habitat, has net surplus of new individuals (more births than deaths) and provides individuals that can “rescue” sink populations

Population Sink = usually consists of individuals occupying less than ideal habitat; has net loss of individuals (more deaths than births). Many areas near o or heavily impacted by humans are population sinks for a number of species

Source

Sink

Stable

Note: arrows imply that exchange of individuals is occurring between patches. If a patch receives an individual it is called immigration, and if an individual leaves it is called emigration and the individual is considered a “disperser”. Immigration is the process keeping the population sinks “alive” and viable. Why might a sink be important to the metapopulation at-large?

Biological Consequences of Fragmentation

• Initial Exclusion – immediate, direct loss of species • Crowding Effect – individuals crowding in to remaining

habitat; problems? • Insularization and Area Effects - • Isolation • Edge Effects • Matrix Effects • Road Issues • Species Invasions

Lexington’s forest “islands” in a sea of urbanization

Insularization and Area Effects • Insularized = to become island-like, isolated, relegated to

habitat islands • If the minimum habitat area and quality requirements are

not met, species cannot persist (e.g. large carnivores in protected areas)

• Area-sensitive species require habitat patches many times larger than their home ranges (the minimum area that satisfies all life history requirements); the area we might predict they need to survive.

Avian examples of area-sensitivity (Figure 7.6)

Edge Effects http://www.youtube.com/watch?v=WGWFh6vCd7I

Core

Edge

Are edge effects good or bad? Should I manage for edge habitat?

Can edges become population sinks/traps?

Black Bears in FL

In the circled area to the right is the location of Florida’s smallest black bear population (Chassowitzka population). In the early 2000s, < 20 individuals remained in this area, and most of those were older females, thus there is concern and a high likelihood this highly isolated population will go extinct. This area was labeled “between the devil and the deep blue sea” being stuck between the Gulf to the west and highways and development on other sides.

Other small population issues as suggested by the black bear in the Greater Chassahowitzka

Ecosystem (GCE)1…

1From Orlando 2003

Florida’s smallest bear population; Bears and big box marts north of Tampa Florida. Here you can clearly see how development forms a high contrast uninhabitable border on most sides of the original forest and wetlands that bears use.

From: Dixon, J. 2004. Conservation genetics of the Florida black bear. MS thesis. University of Florida, Gainesville, FL. 94 pp.

Reduced genetic variability (symptom of problems at the landscape scale…)

These bears have lost a tremendous amount of genetic diversity from being isolated (lower the Ho value, the less genetically diverse). We continue to study the Highlands bear population, Florida’s 2nd smallest.

Figure 3. Noise levels collected on transects at 50 meter intervals into forest from the edges of U.S. Highway 19 (solid line), county roads 595, 550 (doted line), an electric power line edge (dashed line).

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Figure 3. Noise levels collected on transects at 50 meter intervals into forest from the edges of U.S. Highway 19 (solid line), county roads 595, 550 (doted line), an electric power line edge (dashed line).

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lNoise levels collected on transects at 50 meter intervals into forest from the edges of U.S. Highway 19 (solid line), county roads 595, 550 (doted line), and an electric power line edge (dashed line).

Bears in Chasshowitzka don’t like the noise found w/n the first 100-200m from development, meaning that they seldom venture there and thus that “sound influenced edge” habitat is lost to use despite it initially appaering as good bear habitat to humans.

The sound zone avoided by bear in the GCE resulted in a 15% reduction of habitat and the loss of 10.4 to 55.3% core area depending on fragment size (Orlando 2003).

Highlands-Glades Counties Black Bear population – 2nd smallest in Florida

http://edition.cnn.com/2009/TECH/09/07/florida.tracking.bears/index.html#cnnSTCVideo (Brief story on Florida’s 2nd smallest bear population and the UK research project there)

Note: In a highly fragmented population of a species (in this case Highlands-Glades bears) it’s important to understand how individuals move between patches, particularly if there is significant mortality associated with movement (e.g. across roads). In this study a probability was assigned to forest blocks that gives us clues as to the likelihood that bears will use it. We then plot the location of bear road kills and try to understand why bears cross in certain areas so that measures can be taken to lower bear-vehicle collisions, but also how to link these disparate patches so that the bear population can remain connected and thus viable into the future.

Road Effects In this example when tracking this small carabid beetle (forest-dweller) it is clear that it seldom crosses the road.

This GPS black bear (Male 34) in southcentral Florida was very informative, showing us how he moved throughout a highly urbanized landscape yet found his way to protected areas (green) via long-distance movements of over 300 miles in 9 months. Notice how he paralleled Interstate 4 (upper left) but never crossed it, but did cross other very busy roads that were less wide. His movement patterns helped U.S. Fish and Wildlife Service delineate the boundary for the new Everglades Headwaters National Wildlife Refuge.

Road Crossings

Wildlife overpasses and underpasses are occasionally used to reduce wildlife mortalities on roads, but also to maintain connectivity within populations when habitat is divided by roads. These structures can be very expensive, and the results are mixed.

Overpass Trans-Canada Highway http://www.youtube.com/watch?v=Pn8fQkzDhHc

Underpass for Florida panther along I-75 (Alligator Alley).

Overpass primarily for large mammals across Trans-Canada Highway, Banff National Park, Canada

http://www.youtube.com/watch?v=qznv5I21MSA From Big Cat Rescue, some background on Florida panthers, habitat loss, and road collisions

Matrix Effects • Not able or willing to move among habitat patches

because of poor habitat in between (matrix). Why? – Increased risk of predation (e.g. mesocarnivores) – Can’t tolerate environmental conditions outside the “good habitat

patches” (too hot/cold too wet/dry, wrong pH, no food or shelter,etc.)

Invasive Species Effects • Fragmentation creates new or makes available old ecological

niches, thus makes it easier for invasive species to colonize areas; thus once established invasive species can themselves further fragmentation by displacing native species. Sometimes this leads to homogenization of the community as native species that remain are often more tolerant of or can effectively compete with invasive species. Overall, however, biodiversity usually declines.

Is Mammoth Cave National Park, KY ecologically functioning as an island? How might you test this hypothesis?

Freshwater Aquatic Systems: Wetlands, Lakes, and Rivers

• Wetlands are transitional areas between terrestrial and aquatic systems characterized by:

hydric soils, mesic/hydric plants, hydroperiod Loss, pollution (toxins and eutrophication), alteration of

hydrological regimes, and invasive species are major threats

• Rivers – only 2% of U.S. streams, and 1/3 globally run

unimpeded : impoundments contribute to endangerment of 91% of fish and 99% of mussels of federally-listed species. Agriculture, siltation, pollution are major threats

Hydrological Connectivity – water-mediated transfer of matter, energy, and organisms within or between elements of the hydrological cycle.

Note: KY has lost ~3/4 of its wetlands

Wetlands

• provide ~ $100 billion in economic benefits

•50% loss in area in U.S.

• 75% loss in area in KY

•

Landscape Scale Freshwater Habitat Loss and Degradation: Lake Chad, Africa

2010

2010

Landscape Scale Freshwater Habitat Loss and Degradation: Aral Sea, central Asia

Unsustainable withdrawal of water for agricultural use has led to this shrinkage in both Lake Chad and the Aral Sea, the latter is also highly polluted

Southwestern U.S. and Water Supplies, particularly on the Colorado River and Rio Grande rivers

Point where the Colorado River ends miles before the ocean due to water loss from irrigation (crops, golf courses, lawns, etc.) and for use in major city water supplies (indicated by red circles)

Marine Systems • About 60% of world pop. lives within 60 miles of coast • About 20% of coastal systems are highly modified • Biggest threats are: global warming, overharvest,

pollution via toxic chemicals, trash, and nitrogen

•

Giant Pacific Garbage Patch

Plastic is major culprit, and some polymers can bind and concentrate toxic chemicals like PCBs, DDT, and other petroleum-based chemicals. Wildlife becomes ensnared or consumes garbage, often leading to death. Made much worse by the 2011 tsunami in Japan.

Eutrophication (is an accumulation of excessive nutrients, particularly nitrates and phosphates from fertilizers and sewage, in aquatic systems that leads to explosive growth of phytoplankton. Sometimes these “algal blooms” can lead to hypoxic (low oxygen) conditions caused by their bacterial decomposition. Massive fish and death of other marine life can occur when oxygen levels drop and neurotoxins from dead phytoplankton are released.

Major Eutrophication Zones: graph indicates % of nitrogen above pre-1900 levels.

Hypoxic “Dead Zones”: are frequently common where pollutant-laden rivers empty into oceans. These can be hundreds of square miles in size and barren of most life in the absence of oxygen. The Mississippi Delta is commonly a hypoxic dead zone.

Chemical Spills and Dumping

Oil spills can cause localized or regional impacts that last for decades or longer

Deepwater Horizon Oil Spill, Gulf of Mexico 2010

Exxon Valdez Oil Spill, Prince William Sound, Alaska, 1989

Worldwide Distribution of Cultivated Systems which have huge impacts on aquatic systems, both freshwater and marine

Erosion off the coast of Madagascar as seen from space

Hydrological Fragmentation: Salmon in the Northwest;

Mussels in KY

• http://www.wildsalmon.org/ (salmon) • http://www.youtube.com/watch?v=MiAs species richness and evenness

increase, so diversity increasesrQo-PB-1w (mussels in KY)

What are some examples of the genetic/species level, population/community level, and ecosystem-landscape level changes in these communities?

Hydrologic Fragmentation at the Major Watershed Level

Habitat Shredding

Habitat Tentacle

Note: Habitat shredding is a specific type of fragmentation that leaves long, linear pieces or “shreds”. These are often found along riparian areas, and can have small branches (also often from streams that empty into them) of intact habitat attached to them called “tentacles”. Shreds can offer more habitat connectivity than patches of habitat, but don’t forget that if they are too narrow, edge effects can render it unusable for many species. Here we see an example of habitat shredding along the KY River on the Jessamine-Garrard County boundary.

Species Vulnerable to Fragmentation: Some Generalizations (very similar to those species characteristics vulnerable to extinction)

• Wide ranging (need lots of space; elephants, wolverines, wolves, migratory animals)

• Nonvagile – poor dispersers, intolerant dispersers (plants that drop heavy seeds, animals that can’t move far)

• Habitat Specialists • Large-patch/Interior requirements – those species that like the

security of a large block of habitat • Low Fecundity/Recruitment – low reproductive rate, or low survival

of offspring to reproductive age • Low Tolerance to Humans

Some Strategies for Coping with Habitat Fragmentation

• Persist or thrive in human-altered habitat patches; take advantage of reduced competition or predation, or increase in preferred resources

• All life history requirements continue to be met in individual patches

• Be mobile. Dispersers often do better because they can move to and incorporate multiple patches; long-term can maintain genetic viability

• However, rapid global warming threatens all these strategies

Strategies for Maintaining Biodiversity in Fragmented Landscapes (I don’t expect you to memorize these, but to think about them)

• Determine connectivity patterns at multiple spatial scales; where are largest patches, and can natural connections be maintained or restored?

• Determine if landscape is critical linkage at larger scales (regional) • Avoid further fragmentation or isolation of remnant areas • Minimize edge effects • Don’t write off smaller patches that could be used as “stepping stones” • Don’t write off value of matrix, find ways to enhance its value • Identify critical movement corridors (e.g. migration routes) • Protect habitat shreds along streams, farm fields, as wide as possible • Minimize the area of disturbed habitats • Identify management practices needed to maintain lost ecological

processes • Avoid disruption of hydrological connectivity – don’t build additional

dams or unsustainably divert water; reverse where possible

Other Major Causes of Habitat Loss and Degradation

Light Pollution

Disrupts biorhythms

Disorients and can kill many nocturnal species

Alters or eliminates behaviors http://globaia.org/en/anthropocene/ (I highly recommend checking this site out for some stunning visuals!)

TOXINS Note: Heavy metals (Lead, Cadmium, Arsenic, Mercury, etc.) can impact a number of critically important enzymes in the body, thereby leading to all kinds of physiological problems, particularly in children. These metals can bind to enzymes and change their shape and ability to function, and/or they block other molecules from interacting with the enzyme.

EDC (Endocrine Disrupting Compounds)

• Examples: – PCBs (polychlorinated bromides, flame retardants) – Dioxin (combustion of plastics/PVC) – Pesticides – chemical stabilizers (phthalates, bisphenol A) – health care products, cosmetics, perfumes

• Teratogenic – harmful to fetus, can lead to birth defects • Carcinogenic – cancer-causing • Metabolic – disrupts metabolic processes • Reproductive – disrupts quality or quantity of gametes

(sperm and egg)

Air Pollution

Impacts of Acid Rain

The buildup of acids in soils and water eventually leads to conditions that are intolerable for many terrestrial and aquatic species.