Biodiversity's 'Holy Grail' Is in the Soil : Soil-Borne Pathogens Drive Tree Diversity in Forests

[Ed Barrow]

Why are tropical forests so biologically rich? Smithsonian researchers have new evidence that the answer to one of life's great unsolved mysteries lies underground, according to a study published in the journal, Nature.

What determines plant diversity in a forest? It's a question even Charles Darwin wanted to unravel. But most research into forest diversity demonstrates only patterns of species survival and abundance rather than the reason for them -- until now.

A team of researchers led by biologists at the University of Wisconsin-Milwaukee (UWM) has shown that soil-borne pathogens are one important mechanism that can maintain species diversity and explain patterns of tree abundance in a forest.

"We've known for a long time that tree seedlings do not grow and survive well under their mothers or other adult trees of the same species," said Scott Mangan, postdoctoral fellow at the University of Wisconsin -- Milwaukee and the Smithsonian Tropical Research Institute in Panama. "One explanation for the maintenance of the diversity of tropical trees is that adult trees harbor pests and diseases that harm seedlings of their own species more than they do seedlings of other species." The experiments show that underground organisms are key to the maintenance of species diversity and patterns of tree-species relative abundance. The detrimental effects of soil organisms from adult trees not only explain seedling growth and survival patterns, but moreover that these effects are much more severe for seedlings of rare species than for seedlings of common species.


http://www.sciencedaily.com/releases/2010/06/100625185424.htm

[damntexdem]

1. Ain't evolution interesting?

And the Creos miss it all.

[mike_c]

2. haven't read the paper yet, but this article ABOUT the paper leaves questions....

There have been lots of theories put forward to explain the latitudinal gradient in species richness-- it's one of the most persistent and intriguing patterns in global biological distribution. THIS particular explanation isn't really an explanation-- or so it appears to me before I read the original paper-- because it uses soil biological richness and diversity to explain the biodiversity gradient, i.e. it simply uses one manifestation of that gradient to explain the entire gradient. There is still likely an outside driver that makes the latitudinal diversity system assume that configuration, INCLUDING the diversity soil of organisms. That the latter might be the driver for tropical tree species richness makes sense, but it doesn't explain the pattern of global diversity-- it just pushes its roots deeper, no pun intended (but I'll take whatever I can get!).

We're still left with hypotheses like the productivity hypothesis, energy hypothesis, time and stability hypothesis, and even wacky ones like the land mass distribution hypothesis and the predator/prey balance hypothesis to explain the underlying pattern using drivers from OUTSIDE the biological systems themselves.

But this sounds like a neat paper to discuss with my ecology students next semester!