Resistance and Resilience

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Science  07 Sep 2001:
Vol. 293, Issue 5536, pp. 1731
DOI: 10.1126/science.293.5536.1731b

The “resistance” of an ecosystem to a perturbation, such as the introduction of an alien species, is a measure of how much the system changes. Its “resilience” is the extent to which it can recover after the source of change is removed.

Knapp et al. have studied the effects of fish introductions and removals on the biota of hundreds of naturally fishless alpine lakes in western North America. The resistance of the lake faunal assemblages to trout stocking was low; the abundance of amphibians and larger invertebrates decreased dramatically, whereas the abundance of smaller planktonic invertebrates often increased. More surprisingly, the resilience of the lakes turned out to be high. In lakes where trout stocking ceased and where there was no suitable trout spawning habitat, the animal assemblages recovered to compositions characteristic of undisturbed lakes, depending on the length of fish occupancy. Thus, further fish removals may be required to protect the fauna of alpine lakes in U.S. national parks and forest wilderness areas, most of which still contain trout. — AMS

Ecol. Monogr.71, 401 (2001).

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