CAMBRIDGE, Mass., Nov. 28, 2006 -- The apple might not fall far from the tree, but new research shows that how it falls might be what is most important in determining tree distribution across a forest. This study of the seed dispersal methods of rainforest trees demonstrates that these methods play a primary role in the organization of plant species in tropical forests.
Joshua B. Plotkin, a junior fellow in the Faculty of Arts and Sciences at Harvard University, and co-author Tristram Seidler will publish their results in the November issue of the journal Public Library of Science Biology.
"Overall, there is a highly significant relationship between mode of seed dispersal and the clustering and arrangement of mature trees in the rainforest," says Plotkin. "This strong correlation demonstrates the long-term impact that these dispersal methods have on the organization of the large-scale forest."
In order to address the paradox of how so many rainforest species can coexist while competing for the same resources, Plotkin and Seidler studied a 50-hectare (500 meters by 1,000 meters) plot of lowland tropical forest at Pasoh Forest Reserve in peninsular Malaysia. They analyzed the dispersal mechanisms and spatial distributions of 561 tree species found in the plot. What they found was that species clustering was strongly correlated to the species' mode of seed dispersal.
Each species was categorized by one of five dispersal methods: ballistic (where seeds are liberated explosively), gravity, gyration (where the progression of seeds to the ground is slowed by the shape of the seeds), wind, and animal, the last of which was sub-categorized by fruit size. The animal subcategories were intended to distinguish among different sizes of animal that might disperse the fruit.
Plotkin and Seidler observed the distribution of individual tree species, determining an average spatial cluster size. Upon comparison across all species and s
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Contact: Steve Bradt
steve_bradt@harvard.edu
617-496-8070
Harvard University
28-Nov-2006