How plant communities endure stress

Survival in a Cape Cod salt marsh

In isolation, seaweeds and barnacles could never survive the heat stress above the tides, but they can persist in groups. Organisms under stress — even competitors — are better off together than apart. Credit: Image courtesy of Bertness lab/Brown University

The Stress Gradient Hypothesis holds that as stress increases in an ecosystem, mutually supportive interactions become more significant and negative interactions, such as competition, become less so. The idea has been hotly debated but is now backed by a review of hundreds of studies co-authored in Ecology Letters by Mark Bertness, professor of biology at Brown, who first formally proposed the hypothesis in 1994. The time has come, he said, to test its application and predictive value.