A Rodent’s Role in Seed Dispersal

Klinger Trapping Crew (5)

Long-time BFREE board member and US Geological Survey Ecologist, Rob Klinger, is an invited speaker for the 50th Anniversary meeting for the Association for Tropical Biology and Conservation meeting in San Jose, Costa Rica during late June.

Below find the abstract for Rob’s presentation.

“Community Effects Of Variation In Strength Of Seed Dispersal And Seed Predation Relative To Seed Predator Abundance”  

Authors: Rob Klinger and Marcel Rejmánek

Seed predation and seed dispersal are often studied as individual effects, but the degree to which their relative importance co-varies with seed predator abundance and how this influences seed fate has not been well-studied. Therefore, we used observational and experimental approaches to investigate the numerical response of a small mammal seed predator, Heteromys desmarestianus, to disturbance induced changes in food availability, and evaluated the degree to which removal and fate of seeds of eight tree species in a lowland tropical forest in Belize were related to the functional response of H. desmarestianus to varying seed densities. Observational data revealed that the total proportion of fruits removed was determined primarily by the numerical response of H. desmarestianus to fruit availability, while removal rates and the proportion of seeds eaten or cached were related mainly to the form of the functional response. The numerical and functional responses interacted though; spatial and temporal numerical responses by H. desmarestianus to total fruit availability resulted in variation in the form of the functional response. Experimental reduction of H. desmarestianus abundance by 90% allowed us to assess the degree to which their rates of seed predation and dispersal limited seed to seedling survival of the eight tree species. In general, the proportion of seeds that germinated was influenced more by high rates of predation than by limited dispersal. Reduction in abundance of H. desmarestianus resulted in an order of magnitude decrease in fruit removal rates and an order of magnitude increase in the absolute and relative numbers of seeds that germinated. However, the proportion of seeds cached remained relatively constant across all periods and between control and removal plots. The results indicate that seed dispersal and seed limitation can occur simultaneously, and their relative strength will be determined largely by the dynamics of seed predator populations.

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