Stability and diversity of ecological communities

Abstract

MAY¹ drew an analogy between large randomly connected cybernetic networks^2,3 and ecosystems. His analysis of stability criteria for such networks seems to contradict the traditional ecological hypothesis that ecosystem diversity contributes to functional stability^4–7. May's analytical solution for large matrices in which each element by itself is stable showed that¹ “too rich a web connectance or too large an average interaction strength leads to instability. The larger the number of species, the more pronounced the effect”. As the number of elements in the matrix increases, the transition region between stability and instability becomes increasingly narrow^1–3. Thus, a complex system perched near this transition region is subject to a self-generating catastrophe upon only a minor modification of system parameters. If these models are applicable to real ecosystems, they obviously have immense implications for resource management as well as ecological theory. I report here an application of May's conclusion to a real ecological system.