Vegetation Communities on Little Tobago Island, Republic of Trinidad and Tobago. Composition and Abiotic and Biotic Controls on Distribution

Trees, ground flora and epiphytes were surveyed across 81 sites on Little Tobago Island, Trinidad and Tobago. Micro-climatic and edaphic parameters were measured at each site. Cluster analysis was used to identify possible vegetation groups. Ordination and logistic regression analysis were used to detect environmental gradients and to describe the influence of the environmental variables on individual plant species. One hundred and sixteen species were found on the island, of which 101 were recorded in this survey. The vegetation community was dominated by native species with individuals of the tree species Coccothrinax barbadensis, Guapira fragrans, Bursera simaruba, and Diospyros inconstans accounting for 66% of all trees surveyed. The sites were classified into five cluster groups based on species composition. One group consisting of 3 sample sites was dominated by the exotic species Bambusa vulgaris and had a significantly different structure due to the multi-stemmed clump habit of the species. No spatial pattern was identified in the distribution of abiotic variables across the island which contributed to the lack of spatial pattern in the distribution of individual plant species. The species found in this survey largely matched those found by Beard in 1944 with a couple of exceptions which may be due to misidentifications in 1944 or decline in species due to disturbance by stochastic events such as hurricanes.