Tree species diversity in small, tropical riparian forest fragments in Belize, Central America

Tree species diversity was measured in a network of very small galleryforests within the Mountain Pine Ridge savanna in Belize. Research focussed onforest patches smaller than 1 ha in size (micro-forests) and linearstrips of trees along creeks lacking interior core zones with low understoreylight levels (tree thickets). Twenty-five micro-forests and 51 tree thicketsites were sampled throughout the savanna. A total of 144 morphospecies 5cm dbh (106 in micro-forests and 117 in tree thickets) werefound, which represents 1/5 of the approximately 700 native tree species in Belize.Most (85.3%) of the species encountered are typically found in tropical rainforests and few are restricted to savanna or riparian environments. Speciesaccumulated at a much faster rate in micro-forests than in tree thickets. Onlyone species, the palm Acoelorraphe wrightii, was extremelyabundant, accounting for almost 30% of all stems. Many of the species werepresent in very low densities: 19% of all species found in micro-forests and 42%of those found in tree thickets had on average one or fewer stems per hectare. Alarge proportion of species were also found infrequently across the landscape,being present in only 36% of micro-forests and at 52% of tree thicket sites. Theresults indicate that networks of very small forest patches can contain highnumbers of species and could therefore contribute to the maintenance of regionalbiodiversity.