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Keywords:

  • landscape;
  • microhabitat;
  • microsite;
  • post-dispersal seed predation;
  • recruitment;
  • scale-dependency;
  • seed dispersal;
  • spatial heterogeneity

Summary

  • 1
    We explored whether seedling recruitment was spatially predicted by seed rain (spatial concordance) at different scales (microsite, microhabitat and site) in the bird-dispersed trees Crataegus monogyna, Ilex aquifolium and Taxus baccata, in temperate secondary forests in north-west Spain.
  • 2
    We propose that both spatial concordance within each scale and consistency of concordance patterns across scales are dependent on differences between seed rain and post-dispersal processes in the partitioning of spatial variance at each scale.
  • 3
    We measured the density of dispersed seeds, the percentage of post-dispersal seed predation by rodents and the density of emerged first-year seedlings at sampling stations distributed throughout five microhabitats (under canopies of parental trees and in open gaps) and four localities over two seasons.
  • 4
    Seed rain density of all tree species varied most at the microhabitat scale, but microsite and site differences accounted for most of the spatial variance in post-dispersal seed predation and, especially, in seedling establishment.
  • 5
    All three species showed concordance between seed rain and seedling establishment at the microhabitat scale, because strong patchiness in avian-generated seed rain overrode the slight uncoupling effects exerted by the more homogeneous post-dispersal processes. Seed rain was also a good predictor of recruitment of Ilex and Crataegus at the microsite scale, but, for Taxus, the rather homogeneous dispersal across microsites contrasted with the heterogeneous post-dispersal losses. At the site scale, only Taxus showed a positive trend of concordance.
  • 6
    Concordance patterns were maintained from microsite to microhabitat in Crataegus and Ilex, and from microhabitat to site in Taxus. Low-variance allocation to the site scale at the seed rain stage precluded complete consistency in Crataegus and Ilex.
  • 7
    Positive responses of recruitment to seed dispersal depended on both species and scale, resulting in a complex template for dispersal-limitation effects on metapopulations and communities.