AMES, Iowa - For decades, scientists have believed that a relationship exists between how much biomass plant species produce and how many species can coexist.
This idea comes from a 1970s study that showed as plant biomass produced called plant productivity - in a system increased, so did the number of plant species referred to as plant richness - to a point. After that point, the number of plant species is thought to decline.
When plotted on a graph, the resulting line forms a hump shape, with maximum species richness occurring at the point of intermediate productivity.
Now it's time to get over the hump, according to new research in the current issue of the journal Science.
Stanley Harpole, assistant professor in the Department of Ecology, Evolution, and Organismal Biology at Iowa State University, was part of the team researching productivity and richness, and he says the research doesn't support that relationship.
"This hump pattern that everyone thought was true . . . it just isn't there," said Harpole. "This hump was the hypothesis for a long time, but it just isn't supportable."
Harpole says that the amount of biomass is one of the more important components of an ecosystem, so there will be worldwide interest in this research.
"Ecologists have long been interested in this relationship between how many plants there are and how much they produce," said Harpole. "For years they [scientists] have been plotting correlations looking at the relationship of biomass to species richness."
There was no 'hump' shape, according to Harpole. In fact, after plotting the data from all the sites, only one of the 65 sites showed a hump-shaped pattern.
"And that is supposed to be the 'true' pattern?" said Harpole.
Harpole believes the original work that led to the predictions for a hump shape was good research, and it showed a correlation between richness and productivity. B
|Contact: Stanley Harpole|
Iowa State University