Local neighborhood and species' shade tolerance influence survival in a diverse seedling bank

Authors

  • Liza S. Comita,

    1. Department of Plant Biology, University of Georgia, Athens, Georgia 30602 USA
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    •  Present address: Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, New York 10027 USA. E-mail: lsc2125@columbia.edu

  • Stephen P. Hubbell

    1. Department of Plant Biology, University of Georgia, Athens, Georgia 30602 USA
    2. Smithsonian Tropical Research Institute, P.O. Box 0843-03092, Balboa Ancón, Republic of Panamá
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    •  Present address: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90024 USA.


  • Corresponding Editor: K. D. Woods.

Abstract

Accumulating evidence suggests that negative density dependence, particularly at early life stages, is widespread in plant communities. We hypothesized that survival in forest seedling banks declines with increasing density of conspecific neighbors and that local-scale effects cause a negative correlation between seedling survival and tree species abundance in the community. We tested these hypotheses using data on 48 956 established seedlings of 235 species over three years in a 50-ha plot in Panama. For all species combined, we found a significant negative effect of conspecific seedling and adult neighbors within 10 m. In species-level analyses, neighbor density affected survival for 45 of 59 species, with effects of conspecifics different from heterospecifics for 29 species. Despite negative effects of local conspecific neighbors, seedling survival tended to be positively correlated with species abundance at the 50-ha scale. However, when accounting for species' shade tolerance, we found a significant negative relationship between seedling survival and species' basal area, but not density, in the 50-ha plot. Our findings indicate that attempts to quantify the contribution of density dependence to tropical tree species coexistence must integrate effects of neighbors across multiple life stages and should also take into account variation in life history strategy.

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