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Increasing community size and connectance can increase stability in competitive communities
1Integrative Ecology Unit, Department of Biological & Environmental Sciences, P.O. Box 65, Viikinkaari 1, Helsinki University, FIN-00014, Finland. mike.fowler@helsinki.fi
Journal of Theoretical Biology
|June 4, 2009
Summary
Increased species and connectance in ecological communities enhance local stability, challenging previous theories. This finding helps explain why complex natural systems often appear stable.
Area of Science:
- Ecology
- Theoretical Ecology
- Mathematical Biology
Background:
- The relationship between ecological community complexity and stability is a long-standing debate.
- Early models suggested increased complexity leads to decreased local stability.
- Empirical observations often show more complex systems are more stable.
Purpose of the Study:
- To investigate how increasing species number and connectance affects local stability in discrete-time competitive communities.
- To reconcile the discrepancy between theoretical predictions and empirical observations of community stability.
- To explore the impact of competitive feedback on community dynamics.
Main Methods:
- Analytical derivations for simple community cases.
- Computer simulations across a range of community sizes and species dynamics (stable equilibria to complex dynamics).
- Analysis of diversity-biomass stability relationships.
Main Results:
- Increasing species number and connectance probability enhances local community stability.
- Increased competitive links reduce per-capita growth rates, stabilizing oscillating dynamics.
- Results remain robust despite trade-offs in species traits and variations in interaction strengths.
Conclusions:
- Community complexity, specifically species number and connectance, can increase local stability.
- This provides a theoretical explanation for the stability observed in complex natural ecosystems.
- The findings offer insights into diversity-biomass stability and the prevalence of simpler dynamics in nature.
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