Predicting extinction risks for plants: environmental stochasticity can save declining populations

An emerging generalization from theoretical and empirical studies on conser vation biology is that high revels of environmental stochasticity increase the likelihood of population extinction. However, coexistence theory has il lustrated that there are circumstances under which environmental stochastic ity can increase the chance of population persistence. These theoretical st udies have shown that the sign of the effect of environmental stochasticity on population persistence is determined by interactions between life histo ry and environmental stochasticity, These interactions mean that the stocha stic and deterministic rates of population growth might differ fundamentall y. Although difficult to demonstrate in real systems, observed life histori es and variance in the vital rates of populations suggest that this phenome non is likely to be common, and is therefore of much relevance to conservat ion biologists.