Sumario: |
We analyzed the differences in species richness, community composition, population
structure and within-tree location of epiphytic bromeliads in contiguous secondary
and mature forests in a premontane area in Costa Rica. Diversity in the mature forest
was highest, and the communities differed in their composition as well as in the
recruitment rates of the dominant species. Guzmania monostachia and Catopsis
nutans dominated the secondary forests, whereas Tillandsia fasciculata and T.
tricolor were more abundant in the mature forest. The secondary forest species
showed high rates of seedling recruitment while the opposite was found for the
mature forest species. Species presence and abundance among and within habitats
did not correlate with their physiological (i.e. CAM vs. C3 photosynthesis) or
morphological attributes. The spatial distribution patterns were similar among
habitats; bromeliads tended to aggregate on a few relatively large phorophytes. The
species shared a similar vertical stratification within habitats, except for the two
dominant species in the early and mid-successional stages, although its ecological
implication is not clear. With some exceptions, conspecifics of different ages were
located on similar substrate types (i.e. stems, primary, secondary, or tertiary
branches) within the tree-crowns, which suggests limited within-tree dispersion.
Differences in species composition and rates of seedling recruitment among
secondary and mature forest may arise from ecophysiological differences among
species; however, the combined effect of seed availability and dispersal differences
may have a larger influence. Thus, epiphyte community assembly can only be understood when the differences in habitat conditions, the availability of
propagules, their dispersal characteristics and requirements for seedling establish ment are known.
& 2006 Gesellschaft fu¨r O¨kologie. Published by Elsevier GmbH. All rights reserved.
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