Global Changes Imperil Many Species.

Two studies by researchers from Oregon State University, Corvallis, suggest that ecosystems can be far more vulnerable than often assumed, subject to disruption by fairly small environmental changes or loss of "minor" species not traditionally thought to be important, and in considerable peril from climatic change. One indicates that some ecological impacts of global warming might be abrupt, significant, and generally underestimated--not just a slow shift of species from one region to another. It found that small changes in ocean temperature could affect important or "keystone" species and trigger large, relatively rapid changes in intertidal ecology.

The other maintains that measures to protect ecosystem health and function must consider not only those keystone species known to play dominant roles, but many less prominent species which, at various times, may actually be highly important. Together, the findings imply that the function of complex ecosystems is both difficult to predict and...