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Along the
grassland-forest continuum, the relative proportion of coverage by
woody plants increases. Concurrently changes in species
composition may occur. Ecosystems with two or more co-dominant
plant species, as oppossed to those with a single dominant
species, are more sensitive to changes in climate, as illustrated
by simulations using forest and grassland "gap" models (Yeakley
et al. 1994). Ecotones, the transition zones between ecosystems
are particularly sensitive to climate, as species are at or near
their tolerance limits. In an upcoming paper in the Proceedings of
the National Academy of Sciences USA (December 8, 1998), we report
on an ecotone shift at our Frijolito Study Site (Allen and
Breshears 1998).
Rapid
Vegetation Responses to Climate: In the News
References
Allen, C.
D., and D. D. Breshears. 1998. Drought-induced shift of a
forest-woodland ecotone: rapid landscape response to climate
variation. Proceedings of the National Academy of Science (USA)
95:14839-14842.
Yeakley, J.
A., Moen, R. A., Breshears, D. D., and M. K. Nungesser. 1994.
Response of North American ecosystem models to multi-annual
periodicities in temperature and precipitation. Landscape Ecology
9: 249-260.
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