Metacommunity structure of tropical forest along an elevation gradient in Puerto Rico

The development of metacommunity theory, which suggests that the diversity and composition of communities is influenced by interactions with other communities, has produced new tools for evaluating patterns of community change along environmental gradients, These techniques were used to examine how plant communities changed along elevation gradients in montane tropical forests. Two transects of 0.1-ha vegetation plots were established every 50 in in elevation in the mountains of eastern Puerto Rico. The transects ranged from 300 m to 1000 m asl and 400 m to 900 m. In each plot, all free-standing woody stems greater than 1 cm in diameter at 130 cm in height were marked, measured and identified. Additional data on three similar transects were taken from the literature. The tipper or lower boundaries of species ranges were significantly clumped along all five transects. Coherence. a measure of the number of gaps in species distributions, was also significant across all transects, and three transects showed significant, albeit low. nestedness. Four sites had significant species turnover. These results Suggest that metacommunity techniques can be useful in searching for patterns of community change present in montane tropical forests.