introduction – landscape ecology
DESCRIPTION
Introduction – Landscape Ecology. Landscape Ecology : Study of landscape structure and processes. Landscape : Heterogeneous area composed of several ecosystems. Landscape Elements : Visually distinctive patches in an ecosystem. Human Land Use Practices. Ecosystem simplification :. - PowerPoint PPT PresentationTRANSCRIPT
Introduction – Landscape Ecology
• Landscape Ecology: Study of landscape structure and processes.– Landscape: Heterogeneous area composed of
several ecosystems.– Landscape Elements: Visually distinctive
patches in an ecosystem.
Human Land Use Practices
Ecosystem simplification:
Intensive Agriculture&
Clean Farming
Timber Extraction&
Fragmentation
Roads: Formation of Barriers in Landscapes
Formation of Terrestrial “Islands”
Habitat Fragmentation • Process of breaking contiguous unit into
smaller pieces; area & distance components
• Leads to:
• Community & Ecosystem processes altered
#patches
Patch isolation
Patch size
Edge
Habitat Fragmentation • area-sensitive species: species that
require minimum patch size for daily life requirements
• Edge effects: influence of factors from outside of a patch
Increased Edge Habitat
Increased Edge Habitat
Edge Effects • Habitat surrounding a patch can:
- change abiotic conditions; e.g., temp.
- change biotic interactions, e.g., predation
Example of nest predation = edge effect of approximately 50 m into forest patch
Habitat Fragmentation • First-Order Effects: fragmentation leads
to change in a species’ abundance and/or distribution
Habitat Fragmentation • Higher-Order Effects: fragmentation
indirectly leads to change in a species abundance and/or distribution via altered species interactions
Habitat Fragmentation: Species-Specific Sensitivity?
• Rare species = more vulnerable
• Wide ranging species = large-area requirements
• Species with reduced mobility = more vulnerable
• Species with low fecundity (related to rarity?)
• Species with short life cycle (or multi-stage life cycle?)
Habitat Fragmentation: Species-Specific Sensitivity?
• Interior-dependent species
• Species vulnerable to human exploitation or disturbance
• Specialist species?
Implications of Changes in Scale
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PredatorPrey
Insects sampled at 10-m intervals for 100 m
Implications of Changes in Scale
0
5
10
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20
25
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35
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PredatorPrey
Insects sampled at 2000-m intervals for 20,000 m
Landscape Processes
• Landscape structure influences processes such as the flow of energy, materials, and species between the ecosystem within a landscape.
Landscape Structure and Dispersal of Small Mammals
Habitat Patch Size and Isolation and Density of Butterfly
Populations
Introduction – Geographical Ecology
• MacArthur defined geographical ecology as search for patterns of plant and animal life that can be put on a map.– Above level of landscape ecology
Island Area and Species Richness
Species-Area Relationship
Island Biogeography
• equilibrium model suggesting number of species occurring on an island represents a balance between immigration (in) and extinction (out)
• Robert MacArthur & E.O. Wilson
Equilibrium Model of Island Biogeography
• Proposed rates of extinction on islands would be determined mainly by island size.– LG near islands will support highest number.– SM far islands will support lowest number.– SM near and LG far will support intermediate number.