© Sara Winter
J. S. Clark, “Individuals and the variation needed for high species diversity in forest trees,” Science, 327:1129–32, 2010.
For 50 years, ecological scientists have puzzled over why forests, which compete for the same few resources (sun, water, soil) are so diverse, when modeling predicts that such niches should yield low diversity. Now, Jim Clark of Duke University has found that trees of the same species can respond in different ways to environmental conditions, creating otherwise unexpected opportunities for coexistence.
Ecological theory predicts that different species have to respond to changes in the environment in substantially different ways in order to coexist successfully. But those differences have never been found in the field. By analyzing growth rates, fecundity, and survival of trees in response to environmental factors, Clark found that differences between trees of the same species are greater than across species. “You really need the individual-level information,” Clark says.
Clark used a dataset of nearly 20 years’ worth of data from 22,000 individual trees in 11 different sites in the southeastern United States. “In a sense,” F1000 Faculty Member Scott Collins writes, “this is sort of a ‘Doohhh’ since we all thought this might be the case, but we never had the data or gumption to document it thoroughly.” The findings reconcile predictions from competing theories of ecological diversity.
Individuals face competition all the time, but climate change may alter the playing field for many trees. “Trying to understand those relationships,” between individuals, their competitors and changing climate is next on Clark’s agenda.
F1000 evaluators: J. Chase (Washington Univ.) • J. Marra (Brooklyn College of the City Univ. of New York) • S. Zeller and B. Schmid (Univ. of Zurich) • S. Collins (Univ. of New Mexico)
Click here for the complete F1000 review of this paper.