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Landscape Ecology

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Landscape Ecology Chapter 21 – PowerPoint PPT presentation

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Title: Landscape Ecology


1
Landscape Ecology
  • Chapter 21

2
Outline
  • Introduction
  • Landscape Structure
  • Landscape Processes
  • Habitat Patches and Corridors
  • Landscape Position
  • Origins of Landscape Structure and Change
  • Climate
  • Organisms

3
Introduction
  • Landscape Ecology Study of landscape structure
    and processes.
  • Landscape Heterogeneous area composed of several
    ecosystems.
  • Landscape Elements Visually distinctive patches
    in an ecosystem.

4
Landscape Structure
  • Landscape structure includes the size, shape,
    composition, number, and position of different
    ecosystems within a landscape
  • Quantified patch shape by ratio of patch
    perimeter to perimeter of a circle with an area
    equal to that of the patch.
  • S Patch shape
  • Increasing value indicates less circular shape
  • P Patch perimeter
  • A Patch area

5
Landscape Structure
6
Fractal Geometry of Landscapes
  • Perimeter estimates of a complex shape depend on
    size of measuring device.
  • Smaller features may only show up with smaller
    measuring devices.

7
Fractal Geometry of Landscapes
8
Two components of spatial scale
9
Quantifying landscape pattern
10
Two principal methods for representing spatial
data
11
Caveats for landscape pattern analysis
  • Classification scheme

12
Caveats for landscape pattern analysis
  • Grain size (resolution)

13
Caveats for landscape pattern analysis
  • Spatial extent

14
Caveats for landscape pattern analysis
  • Appropriate landscape metrics- most metrics are
    correlated- what constitutes a significant
    change
  • References- Riitters, K. H. et al. 1995. A
    factor analysis of landscape pattern and
    structure metrics. Landscape ecology 10 23-39.-
    J. A.G. Jaeger. 2000. Landscape division,
    splitting index, and effective mesh size new
    measures of landscape fragmentation. Landscape
    ecology 15115-130.

15
Landscape metrics
  • Metrics of landscape composition
  • Measures of spatial configuration contagion
    patch-based metrics
  • Software for spatial pattern analysis -
    FRAGSTAThttp//www.umass.edu/landeco/research/fra
    gstats/fragstats.html- Patch Analysthttp//flash
    .lakeheadu.ca/rrempel/patch/

16
Research tools for landscape ecology
  • GPS- Overview http//www.colorado.edu/geography/g
    craft/notes/gps/gps_f.html
  • GIS- ESRI http//www.esri.com/
  • Remote sensing photogrammetry- SPOT
    http//www.spotimage.fr/html/_167_.php- LiDAR
    http//www.aeromap.com/lidar- Leica Geosystems
    http//www.gis.leica-geosystems.com/default.aspx-
    VLS http//www.featureanalyst.com/index.htm

17
Landscape Processes
  • Landscape structure influences processes such as
    the flow of energy, materials, and species
    between the ecosystem within a landscape.

18
Landscape Structure and Dispersal of Small Mammals
  • Ecologists have proposed landscape structure can
    influence movement of organisms between
    potentially suitable habitats.
  • Metapopulations Populations of many species
    occur in spatially isolated patches, with
    significant exchange of individuals.
  • Rate of movement of individuals between
    subpopulations can affect species persistence in
    a landscape.

19
Landscape Structure and Dispersal of Small Mammals
  • Diffendorfer et. al. studied how patch size
    affects movement of three small mammal species.
  • Predicted animals would move farther in more
    fragmented landscapes.
  • Must move farther to obtain resources.
  • Predicted animals would stay longer in more
    isolated patches.

20
Landscape Structure and Dispersal of Small Mammals
21
Habitat Patch Size and Isolation and Density of
Butterfly Populations
  • Hanski et. al. found butterfly density
    significantly affected by size and isolation of
    habitat patches.
  • Population size within patch increased with patch
    area.
  • Population density decreased as patch area
    increased.
  • Isolated patches had lower butterfly densities.
  • Population partially maintained by immigration.

22
Habitat Patch Size and Isolation and Density of
Butterfly Populations
23
Habitat Corridors and Movement of Organisms
  • Connecting habitat fragments with corridors of a
    similar habitat has long been an approach to
    mitigating the effects of habitat fragmentation.
  • Haddad and Baum found corridors influenced the
    movement of butterflies associated with early
    successional habitats.

24
Landscape Position and Lake Chemistry
  • Webster explored how lake position in a landscape
    affected chemical responses to drought.
  • Lake position in landscape determined portion of
    water received as groundwater.
  • Upper lakes dropped more than lower lakes.
  • Concentration of dissolved ions increased most at
    upper and lower ends.

25
Landscape Position and Lake Chemistry
26
Origins of Landscape Structure and Change
  • Geological processes such as volcanism,
    sedimentation, and erosion are a primary source
    of landscape structure.

27
Soil and Vegetation Mosaics In Sonoran Desert
  • McAuliffe showed bajadas in Sonoran Desert are
    complex mosaic of distinctive landforms.
  • Found wide range of soil types and plant
    distributions that correspond closely to soil age
    and structure.
  • Soil structure influences perennial plant
    distributions.
  • Plant distributions map clearly onto soils of
    different ages.

28
Soil and Vegetation Mosaics In Sonoran Desert
29
Climate and Landscape Structure
  • McAuliffe Soil mosaics consisted of patches of
    material deposited during floods originating in
    nearby mountains.
  • Materials eroded from mountain slopes and
    deposited as alluvium on surrounding bajadas.
  • Alluvial deposits gradually changed dependent
    upon climate.
  • Different soils and plant types.

30
Organisms and Landscape Structure
  • Many studies have focused on conversion of forest
    to agricultural landscapes.
  • Eastern NA, many abandoned farms have reverted to
    forest, thus forest cover has increased.
  • Similar patterns in parts of Europe.

31
Organisms and Landscape Structure
  • Hulshoff found forest and heathland coverage
    changed over time as well as number and average
    area of patches.
  • Cadiz Township - agricultural economy converted
    area from forest to farmland.
  • Economy collapsed in response to introduction of
    synthetic fertilizers and inexpensive imported
    wool.

32
Organisms and Landscape Structure
33
Organisms and Landscape Structure
  • African elephants knock down tress.
  • Change woodland to grassland.
  • Kangaroo Rats dig burrow systems that modify soil
    structure and plant distributions.
  • Beavers cut trees, build dams and flood
    surrounding landscape.
  • At one time, beavers modified nearly all
    temperate stream valleys in Northern Hemisphere.

34
Organisms and Landscape Structure
  • Johnston and Naiman documented substantial
    effects of beavers on landscape structure.
  • Over 63 yrs, area created by beavers increased
    from 200 ha to 2,661 ha.
  • Changed boreal forest landscape to complex mosaic.

35
Organisms and Landscape Structure
  • Beaver activity between 1927-1988 increased
    quantity of most major ions and nutrients in
    impounded areas. Three possible explanations
  • Impounded areas may trap materials.
  • Rising waters captured nutrients formally held in
    vegetation.
  • Habitats created by beavers may promote nutrient
    retention by altering biogeochemical processes.

36
Fire and Structure of a Mediterranean Landscape
  • Minnich used satellite photos to reconstruct fire
    history of S. CA and N. Baja (1971-80).
  • Landscape consisted of patchwork of old and new
    burns.
  • Similar climates with deviated fire histories
  • Fire suppression in S. CA allowed more biomass
    accumulation and resultant large fires.
  • Small burns more frequent in N. Baja.
  • Other factors

37
Review
  • Introduction
  • Landscape Structure
  • Landscape Processes
  • Habitat Patches and Corridors
  • Landscape Position
  • Origins of Landscape Structure and Change
  • Climate
  • Organisms

38
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