Physical variables influencing macro-invertebrate assemblages in epiphytic bromeliads in the rain forest of Belize
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Epiphytic bromeliads from the genus Aechmea are found on many different tree species in the tropics. These bromeliads have evolved water storage tanks where they are able to host many different macro-invertebrate species. The aim of the present study was to assess if six physical variables: i) tree height, ii) tree width, iii) bromeliad weight, iv) bromeliad longest leaf length, v) bromeliad temperature and vi) bromeliad position, have an effect on macro-invertebrate assemblages in Aechmea bromeliads found on the canopy of the endangered Fiddlewood tree (Vitex gaumeri). Twenty-five Aechmea bromeliads from 15 Fiddlewood trees were collected, and a total of 136 morpho-species where recorded. A sample-rarefaction curve showed that new species are expected to be added with increased sampling effort. Results of backward stepwise regression examining aspects of physical variables affecting morpho-species richness showed that bromeliad weight was the only variable that yielded significant results (P= 0.005, R2= 29.77). Additionally, results from a nonmetric multi-dimensional scaling (MDS) ordination shows that each bromeliad sampled contained very dissimilar faunal assemblages in terms of composition and abundance. Results are consistent with other studies showing that weight is a significant predictor of macro-invertebrate richness. I conclude that the importance of these plants and their associated animal communities must not be underestimated. Further research on epiphytic communities may bring increased insights on potential effects of climate change on tropical ecosystems and may prove useful for the enhancement of forest management strategies.