In the new paper, the researchers report the results of research aimed at learning how corridors affect plant species with innately different abilities to get around.
Perhaps unsurprisingly, the scientists found that wind-borne plants and bird-dispersed plants colonize wildlife habitats connected by corridors more quickly and at farther distances than they do isolated habitats. The surprise was that the same is true for what the scientists consider "unassisted" plants, or those with no obvious means of moving their seeds.
The result left the researchers puzzled. "We come right out and say in the paper that we don't understand this," Levey said.
Physical forces clearly aren't adequate to cause the phenomenon, the paper notes.
"Gravity dispersal from low-growing shrubs, forbs and grasses, which typically moves a seed no more than a few meters per year, cannot account for the rapid colonization of connected patches 150 meters distant," the paper says.
With no obvious alternative, Levey said one possible explanation is that the plants' seeds aren't as unassisted as they appear. For example, it's possible that herbivores eat the seeds, even if they are not recognized as normal forage. "My hunch is that these plants are browsed by deer that are really after the leaves," Levey said. "They eat the seeds along with the leaves, and then defecate the seeds somewhere else."
Perhaps improbably, given the randomness of deer defecation, the researchers are testing this hypothesis.
Caleb Hickman, a graduate student in the Washington University Ecology, Evolution, and Population Biology Program, has collected fecal samples left behind not only by deer, but also
|Contact: Doug Levey|
University of Florida