Systems Approach. Ecosystem Community Population.
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Transcript of Systems Approach. Ecosystem Community Population.
Community-Populations of different speciesthat interact.
Ecosystem
- the various communities of organismsinteracting with the environment.
Landscape -a physical area such as a watershedconsisting of various landscape elements(fields, forests) and the species found.
Community
• Species richness
• Species diversity
• Functional groups
• Life Forms
• Trend Analysis
• Statistical Approach
• Are there patterns in community structure?
• If so, what has caused this pattern
• Competition
• Predation
• Time
• Size of patches (islands)
Equilibrium Non-equilibrium
Mean Variation
Predictability Unpredictable
Competition
Island Biogeography Disturbance
Succession
Island Biogeography
• 2 processes - extinction and colonization
• Function of – island size and distance frommainland.
-fire, insect damage, wind, flooding
-unpredictable in space and time
-results in non-equilibrium dynamics
-recognized as being central to ecosystems
Disturbance a non-equilibrium concept
Complexity Stability Debate
• Elton Complexity -> Stability• May 1970’s Modeling – Not so!
• Subsequently refuted (late 80’s & 90’s)• Yodzis - modeling
– Tillman – experiments– BUT we still did not understand the nature of
stability
Summary• Populations
– movement– Fragmentation– Spatially structured populations
• Communities– Dynamic equilibrium/non-equilibrium– Competition– Island Biogeography
• Protected areas - corridors
– Disturbance• Intermediate disturbance hypothesis• predator mediated co-existance
• Ecosystem stability