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Keywords:

  • Borrowing strength;
  • community compensatory trend;
  • crossed random effects;
  • density dependence;
  • generalized linear mixed models;
  • Gutianshan;
  • habitat association;
  • Janzen–Connell hypothesis;
  • seedling survival;
  • species coexistence;
  • subtropical broad-leaved forest

Ecology Letters (2010) 13: 695–704

Abstract

How extraordinary numbers of species can coexist in hyper-diverse communities remains unresolved. While numerous hypotheses have been proposed based on observational and theoretical investigations, little is known about which mechanisms are truly active in forest communities and less is known about their relative contributions to community assembly. In this study, generalized linear mixed models with crossed random effects were used to assess the relative contributions of density dependence and habitat association to community-level diversity maintenance. Species habitat associations were classified based on soil nutrients, topography and species composition. Local neighbourhood effects were also addressed with spatially explicit models of seedling survival. The results shown here reveal that local- and community-level seedling dynamics were consistent with density-dependent predictions, although habitat association played a more important role in shaping short-term seedling survival. We conclude that density dependence could promote species coexistence on the premise of habitat partitioning.