In 2010, 87 permanent plots, established in 2001 in the San Juan Watershed in Puerto Rico, were inventoried to assess changes in species composition and structure across urban land uses. Forty-nine percent of the trees (3,670 trees/acre) inventoried in 2001 died, but 64 percent of the trees (7,511 trees/acre) inventoried in 2010 had grown since 2001. Vacant lands had the highest and upland forests had lowest annual mortality rates. Species richness increased from 68 species in 2001 and 85 species in 2010. Natural regeneration in upland and mangrove forests accounted for most of the new stems added. Residential areas had the highest and vacant lands had the lowest richness. Trees grew fastest in residential areas (0.55 inch per year) and slowest in mangrove forests (0.12 inch per year). Overall, growth of non-native and invasive species was best correlated with human population density, whereas growth of native species was best correlated with tree density. Much of vegetation dynamics observed in the San Juan Watershed can be attributed to human activities.