The composition of plant communities changes with elevation in the Luquillo Experimental Forest. The goal of this project is to document the patterns of these changes, and in particular, to determine whether the distributions of individual species are independent of one another, or whether they are related, in either a congruent or a hierarchical manner. Twenty-four permanent vegetation plots, each 50m by 20m are being established in the LEQ, with eight plots each along three rivers, the Sonadora, Icacos, and Mamayes. The plots are being established at every 100m in elevation, starting at 200m above sea level. All woody, free-standing stems greater than 1cm dbh are being marked, identified and mapped into 5x5 subquadrats. We anticipate that gradient analysis will show whether the distributions of species are coincident or independent, enabling us to evaluate whether separate, genuine plant communities exist in the LEQ. Because the plots are permanent, we also expect that they will also us to better evaluate how different vegetation types, at different elevations, respond to large scale disturbances, especially hurricanes.