Habitat interspersion – Leopold’s Law of Interspersion.
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Transcript of Habitat interspersion – Leopold’s Law of Interspersion.
habitat interspersion –
Leopold’s Law of Interspersion
Human Land Use Practices
History of Landscape Ecology• “European School”
– roots back to those of ecology
– typing, classifying, naming
– landscape architecture, planning, designing
• “American School”– young = early 1980’s
– focus on natural systems
– theory & models, some field experiments
What is Landscape Ecology?
• Meta-analysis of papers in Landscape Ecology (Wiens 1992) – 1st 5 yrs of journal– Most studies are large scale
(landscapes are big)– Most studies are descriptive or
conceptual– Experiments difficult to conduct,
thus modeling– Emphasis on vegetation pattern /
land use pattern– Humans = impt. part of systems
What is Landscape Ecology?
• Hobbs (1997) – 2nd 5 years of Landscape Ecology– Less descriptive
studies– More “methods” and
modeling studies, no expts.
– More quantitative / statistical analysis (spatial stats)
Emergence of Landscape Ecology
Equilibrium View
Structure
Function
?
?
?
?
Emergence of Landscape Ecology
Dynamic View
Structure
Function
Ecological Scaling: Scale & Pattern
• Acts in the “ecological theatre (Hutchinson 1965) played out across various scales of space & time
• To understand these dramas, one must select appropriate scale
Tem
pora
l Sca
le
Spatial ScaleFine
Sho
rt
Coarse
Lon
g
Recruitment
Treefalls
Windthrow
Secondary Succession
Species Migrations
SpeciationExtinction
Fire
Ecological Scaling: Scale & PatternA
mer
ican
Red
star
t
Least Flycatcher
Am
eric
an R
edst
art
Least Flycatcher
Local Scale(4 ha plots)
Regional Scale(thousands of ha)
Ecological Scaling: Definitions• Ecological scale & cartographic scale are exactly opposite
– Ecological scale =
– Cartographic scale =
Ecological Scaling: Components of Scale
• Grain = finest component of environment that can be differentiated up close
• Extent = range at which a relevant object can be distinguished from a fixed vantage point
Fine CoarseScale
ExtentGrain
Ecological Scaling: Components of Scale• )
Identifying the “Right” Scale(s)
• No clear algorithm for defining
• Autocorrelation & Independence • Life history correlates
• Dependent on objectives and organisms
• Multiscale analysis!
• e.g., Australian leadbeater’s possum
Multiscale Analysis
• Species-specific perception of landscape features : scale-dependent
– e.g., mesopredators in Indiana
• Modeling species distributions in fragmented landscapes
Spatial and TemporalEcology of Raccoons
Gehring and Swihart. 2003. Biological Conservation109:283-295
Brown and Litvaitis. 1995. Canadian Journal of Zoology 73:1005-1011
Hierarchy Theory
• Lower levels provide mechanistic explanations
• Higher levels provide constraints
Scale & Hierarchy Theory
• Hierarchical structure of systems = helps us explain phenomena
–Why? : next lower level
–So What? : next higher level
• minimum 3 hierarchical levels needed
Constraints (significance)
Level of Focus (level of interest)
Components (explanation)
Landscape PatternI. Landscape Components
(attributes of features or spatial elements)
landscape are comprised of:
- corridors
- patches
- matrix
Landscape PatternI. Landscape Components
(attributes of features or spatial elements)landscape are comprised of:
- corridors- patches- matrix
A. CompositionB. ConfigurationC. Connectivity
Relative to landscape spatial elements….
How much of the area is comprised of each type of spatial element?How are spatial elements arranged in space?
How do these attributes change through time?
How does one quantify landscape pattern?How do biotic communities interact with pattern?
• Patch –
• Corridor
• Matrix –
Landscape Pattern Patch-Corridor-Matrix Model
Landscape PatternPatches
Defining patches using vector data• Digitizing = delineating polygon patches using remotely-
sensed data (e.g., DOQ) based on visual interpretation of patch boundaries; subjective, but ground truthing needed
DOQ Vector Coverage
Landscape PatternPatches
Defining patches using raster data• Satellite sensor = delineating pixel-shaped patches based on
spectral signatures; aggregating cells based on shared attributes
DOQ Raster Coverage
• Patch boundaries meaningful only when referenced to particular scale & phenomenon; resolution impt., gradients or discrete boundaries?
Landscape Pattern Patches
• Definition based on function…..
• Habitat – increase connectivity by providing breeding habitat…facilitate gene flow
• Facilitated Movement – increase connectivity by facilitating dispersal, migration, and/or range shifts
• Barrier or Filter – prohibit (barrier) or impede differentially (filter) movements
Landscape Pattern Corridors
Facilitated Movement Corridors
Landscape Pattern Corridors
Facilitated Movement Corridors
• Selectivity (s): degree of discrimination of possible pathways
• Resistance (k): survival cost per unit time spent in corridor
• Velocity (v): avg rate of movement through
• Final evaluation = immigration rate
Landscape Pattern Corridors
Barriers & Filters
Landscape Pattern Corridors
• Most abundant• Highest connectivity
Landscape Pattern Matrix