Have Your Plants and Eat Them, Too

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Science  12 Sep 2008:
Vol. 321, Issue 5895, pp. 1419
DOI: 10.1126/science.321.5895.1419c

An experimental study of Arctic vegetation shows that herbivores can exert a strong influence on the ecological outcomes of climate warming in plant communities. Numerous studies have shown that warming leads to changes in the biomass, structure, and composition of plant communities. In Arctic tundra in particular, warming leads to increases in aboveground plant biomass and of shrubby vegetation at the expense of grasses. Post and Pedersen conducted a 5-year experiment in which large vertebrate herbivores (musk ox and caribou) were either excluded from or allowed access to artificially warmed or ambient temperature exclosures. The warmed plots from which the herbivores had been excluded showed the expected transition to higher biomass and domination by woody plants (dwarf birch and willow). However, the plant communities on the grazed warmed plots were indistinguishable from those on the ungrazed ambient plots after 5 years. These results suggest that large herbivores might be useful in mitigating the effects of climate change in tundra—and perhaps in other rangeland habitats. — AMS

Proc. Natl. Acad. Sci. U.S.A. 105, 12353 (2008).

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