For decades, ecologists have toiled to nail down principles explaining why some habitats have many more plant and animal species than others.
Much of this debate is focused on the idea that the number of species is determined by the productivity of the habitat.Shouldn't a patch of prairie contain a different number of species than an arid steppe or an alpine tundra?
Maybe not, says an international team of scientists that pooled its resources to re-evaluate the relationship between species numbers and habitat productivity.
The innovative, standardized global sampling of 48 sites on five continents yielded an unprecedented data set.
"Our study shows no clear relationship between productivity and the number of plant species in small study plots," says Utah State University plant ecologist Peter Adler.
Scientists say Adler's and his colleagues' findings represent a significant advance in ecological thought. The findings appear in this week's issue of the journal Science.
"We challenged a prevailing model developed in the early 1970s by British ecologist J. Philip Grime," says Adler, lead author of the paper. "He proposed that the number of species rises then declines with increasing productivity."Though hotly debated, this "hump-shaped" model has remained a textbook standard for nearly four decades.
"In the search for underlying principles of ecology in a very complex natural world, it's inevitable that even long-standing and accepted theories will be debunked as more data are accumulated and synthesized," says Henry Gholz, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research.
In an "Emperor's New Clothes" moment, Adler remembers skeptical observations about the hump-shaped model made by graduate students in his classroom.
"'Why do ecologists spend so much time on this model when the evidence to support it
|Contact: Cheryl Dybas|
National Science Foundation