In a finding that could have important implications for rainforest preservation, a researcher from the University of California, Davis, reports that seeds that fall to the ground in small fragments of tropical rainforests are three to seven times less likely to sprout than those that fall in larger, continuous forests.
"Rainforest fragments are subject to many conditions, called 'edge effects,' that make them less hospitable to germinating seeds," said Emilio Bruna, a doctoral student in the UC Davis Population Biology Graduate Group. "Fragments are hotter and drier, and have more light penetrating the canopy to the forest floor, than continuous forests do. Those aren't the conditions that rainforest plants are adapted to, and these new results suggest that the seeds simply can't survive."
What's more, Bruna said, other research has suggested that plants in fragments could become inbred, which could make their seeds less likely to germinate in the first place. Such inbreeding, coupled with edge effects, could push the reproduction rate so low that the populations in forest fragments would eventually die away.
Bruna's research was conducted at the Biological Dynamics of Forest Fragments Project in Manaus, Brazil, which is administered cooperatively by the Smithsonian Institution and Brazil's National Institute for Research in the Amazon. It was funded by UC Davis, the Smithsonian Institution and the U.S. National Science Foundation. His report was published in the Nov. 11 issue of the journal Nature as a peer-reviewed "Brief Communication."
Media contacts:
-- Emilio Bruna, in Manaus, Brazil (on Eastern Standard Time), until Nov. 18, work 55-92-642-1148, home 55-92-964-7494, embruna@ucdavis.edu; at UC Davis after Nov. 19, 530-752-3940, embruna@ucdavis.edu.
-- Sylvia Wright, News Service, 530-752-7704, swright@ucdavis.edu.
Journal
Nature