It's not the number of species per se. The primary result of the study is that competition between animals, plants and other forms of life is a sideshow. Instead, the true measure of a community's biological health and stability is the wherewithal of just some species to withstand environmental changes such as a warmer climate, a chemical change in the atmosphere or changes in land use. That is not to say, Ives stressed, that biodiversity has no practical importance. It does, especially in the face of unpredicted, large-scale environmental shifts, he says.
Biodiversity is an insurance policy against unknown environmental fluctuations and disturbances.
According to Gross, the model, like an analysis of the stock market, looks at variability through time, and identifies stability in an ecological community as a measure of how much populations of species fluctuate in the face of environmental change. The hope, according to the Wisconsin scientists, is that the model will contribute to a better understanding of ecosystem dynamics, how ecosystems change along with the larger environment. The work, says Ives, should not be considered an argument against the importance of biodiversity. If you wish to quote from any part of this story, please credit University Of Wisconsin-Madison as the original source.