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