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Predicting species composition in the tropical forests of the future: how tree species vary in their susceptibility to defaunation
  • Peter Williams,
  • Jedediah Brodie
Peter Williams
University of Montana Missoula
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Jedediah Brodie
University of British Columbia
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Abstract

Overhunting is extirpating large animals across tropical forests, affecting tree populations and potentially global carbon cycling. Species reliant on large-bodied seed dispersers may be particularly negatively affected. But defaunation also affects seed predation, trampling of seedlings, and conspecific density dependence. Therefore, defaunation predictions must incorporate multiple plant-animal interactions in the context of the entire tree life cycle. Because we cannot conduct such analyses for every species, we assess whether we can predict species' responses to defaunation based on phenotypic and demographic traits. Using population models, Monte Carlo simulations, and syntheses of demographic data, we found that responses to defaunation were best explained by how hunting altered seed predation, particularly for small-seeded angiosperms. How tree species will respond to defaunation still cannot be precisely predicted, but ascertaining how seed predation varies across species and hunting scenarios could greatly enhance our understanding of changing species composition and carbon dynamics in defaunated forests.