Associations between soil variables and vegetation structure and composition of Caribbean dry forests
Soil–vegetation associations have been understudied in tropical dry forests when compared to the amount of extant research on this issue in tropical wet forests. Recent studies assert that vegetation in tropical dry forests is highly heterogeneous and that soil variability may be a contributing factor. In this study, we evaluated the relationship between soil variables and vegetation structure and composition between 2 dry-forest types, plateau and depression forests, considered distinct by prior vegetation studies performed on Mona Island. Depression-forest sites are of particular interest because they are critical habitats for the endangered Cyclura cornuta stejnegeri (Mona Island Iguana) on the island. These stands establish at sinkholes within the island’s limestone platform where there are deeper soils. Plateau forest is the dominant vegetation association on the island and has been characterized as a low-productivity forest type with an open canopy. We asked 2 main questions in this study: (1) Are depression and plateau forests distinct types that can be distinguished in terms of plant-species structure, diversity, and soil features? and (2) Can we identify associations between soil and vegetation features? We performed vegetation and soil analyses at 6 different depression- and plateau-forest sites on Mona Island. Contrary to the suggestions of previous studies, we did not detect any significant differences between depression and plateau forests in any measured vegetation or soil variables. We discuss several hypotheses to explain our results.