A comparison of leaf litter diversity in wet and dry tropical forests

It is difficult to quantify tropical forest diversity without the skills of a trained taxonomist to identify species. What can we learn about tropical forest diversity by sampling dead leaves from the forest floor? We separated leaves collected from 0.25 m2 quadrats into morphospecies and weighed them. We found an average of ~ 22 morphospecies in each quadrat regardless of location. We identified nearly 80 different kinds of leaves at La Selva, compared to only 30 at Palo Verde. Consequently, the Palo Verde samples were much more similar to each other (had a much higher Sorenson Community Coefficient). There was, however, no correlation between this measure of quadrat similarity and distance between samples in either forest. Species area curves from Palo Verde suggest that our 2m2 sample yielded most of the species in the plot; by contrast, our La Selva species area curves were similar to typical wet forest curves in that they showed little evidence of saturation. As expected, we found the wet forest at La Selva to be more diverse than the dry forest at Palo Verde. Sampling leaf litter is an effective (if tedious) way to assess forest diversity.

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