Living in Harmony

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Science  18 Jan 2002:
Vol. 295, Issue 5554, pp. 409
DOI: 10.1126/science.295.5554.409b

The sedimentary fossil pollen record has allowed paleoecologists to make detailed reconstructions of the changes in vegetation composition that have taken place across the Northern Hemisphere during the Pleistocene. Frequently, they have found that plant species were grouped into communities and assemblages with no counterparts in the present day, and they have debated whether these “no-analog” communities signify vegetation that was at equilibrium with its corresponding climate or instead reflect disequilibrium owing to the effects of rapid climate fluctuations.

Williams et al. have analyzed pollen assemblages from North America at intervals since the last glacial maximum and have tested their correspondence with simulated no-analog climates. They find good spatial and temporal relationships with the simulated climates, as well as synchronicity between climate change and vegetational change, supporting the idea that no-analog vegetation was at equilibrium with its surroundings. Thus, not only are fossil pollen assemblages a useful source of information about past climatic conditions, but they show that new idiosyncratic assemblages of plant species will likely develop in response to future climate change. — AMS

Ecology82, 3346 (2001).

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