Tropical forest community composition and structure along an elevational gradient in Puerto Rico.
Barone, John1, Thomlinson, John1, Anglada Cordero, Pedro1, Brokaw, Nicholas1, Zimmerman, Jess1, 1 Institute for Tropical Ecosystem Studies, San Juan, PR, USA
ABSTRACT- In the Luquillo Mountains of Puerto Rico, we established three transects of 0.1 ha vegetation plots every 50 m in elevation in which we identified, marked and measured all the free-standing woody stems of at least 1.0 cm. To assess how the forest changed with elevation, we analyzed clustering of the elevational ranges and modes of species, and the degree of nestedness for the two longer transects. We also used non-metric multidimensional scaling to assess how the community composition varied with elevation and transect. The upper boundaries of species ranges were significantly clustered on both transects, while lower boundaries were not. Species modes were not clustered, but species distributions were significantly, though modestly, nested. Non-metric multidimensional scaling showed that plant community composition did not change gradually with elevation. Axis 1 scores for all three transects show abrupt transitions across plots. Comparisons with similar elevational transects in other tropical forests show that both upper and lower boundaries of species distributions are frequently clustered.
Key words: metacommunity, elevational gradient, Luquillo Mountains, Puerto Rico
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