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Science  13 May 2011:
Vol. 332, Issue 6031, pp. 768
DOI: 10.1126/science.332.6031.768-b

Climate change impacts are often assessed by tracking single species' responses. Species exist as part of larger biological communities, however, and environmental changes can influence how species interact and allocate resources. One approach for assessing community-level change is to look at “aggregate properties,” the physical and energetic components of a community produced by the contribution and consumption of all its members. These include total abundance, biomass, and energy use. Community aggregate properties are typically thought to be more resistant to disturbance than are single species because of compensatory dynamics among community members.

According to Rowe et al., however, these properties do indeed respond to persistent environmental changes, and such responses may be important indicators of the large-scale ecological impacts of climate change. The estimated total abundance, biomass, and energy use of a small mammal community, consisting of over 20 species, sampled 80 years ago in the Ruby Mountains of Utah, was compared to the same properties measured in the modern community. All properties showed marked declines and a shift in allocation away from diet and habitat specialists to generalists. These findings suggest that climate warming and increased variability in precipitation have reduced primary productivity, resulting in not only a decrease in small mammal biomass but also an increased prevalence of ecological generalists better able to respond to an idiosyncratic fluctuation in resources.

Ecology 92, 10.1890/10-1634.1 (2011).

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