Monday, August 6, 2007

PS 10-118: Life as a seed: The influence of nearest neighbors on seed removal

Jaclyn L. Schnurr1, Richard S. Ostfeld2, and Charles D. Canham2. (1) Wells College, (2) Institute of Ecosystem Studies

Life as a seed: the influence of nearest neighbors on seed removal

In the temperate deciduous forests of the northeastern United States, the majority of the dominant tree species disperse their seeds during the fall, causing a heterogeneous mixture of seeds to be present at a specific location at one time. Because these seeds vary in size and palatability to small mammals, some seed species, such as Quercus acorns, may alter the risk of removal of neighboring, less preferred species. The presence of a neighboring acorn could attract seed predators, elevating risk that a neighboring seed will be removed, or it could divert the attention of seed predators away from a neighboring seed. During the fall of 1994 we established 52 1 x 1 m quadrats at 2 sites in northwestern Connecticut, and within each quadrat we randomly placed 1 seed of 5 different seed species every 10 cm. We checked the seeds after 1 week and recorded seed fate. Using logistic regression we determined whether the species of nearest neighbors caused changes in the risk of removal. Contrary to our expectations, we did not find that presence of an acorn affected the removal rates of other seeds. At this scale there was no effect of neighboring species on seed removal, indicating that risk of removal of naturally occurring seeds, separated by at least 10 cm, is independent.