Microenvironment and floristics of different edges in a fragmented tropical rainforest

Understanding edge effects in different remnants of natural vegetation is crucial for the management of many fragmented landscapes. We compared edges of different wooded habitats in a fragmented tropical rainforest in Los Tuxtlas, Veracruz, Mexico. Selected habitats in a pasture matrix included four forest fragments (>50 ha), four linear forest remnants along streams (riparian forest), and eight isolated remnant forest trees (four fenced and four without fences). Edge habitats were defined in terms of microclimate, vegetation structure, and floristic composition. In forest-pasture sites, significant edge effects were detected for some variables but depth of influence varied Compared to the other habitats, riparian sites and isolated trees without fences exhibited distinct edge conditions. isolated trees fenced for 54 months, however, exhibited some microenvironmental conditions similar tc, those of forest interior. In total, 244 woody plant species were recorded in the sampled area (<1 ha), and these represented 56% of woody, species reported for Los Tuxtlas reserve. Only two species, Acalypha diversifolia and Siparuna andina, occurred in the interior, edge, and pasture of all studied landscape units. Twelve species occurred in all edges and pastures (e.g., Acacia mayana, Tabernaemontana arborea, Cupania glabra, Stemmadenia donnell-smithii). Twenty-six species were found exclusively at edges whereas 44 species were recorded only in interiors. Fenced, isolated trees can provide a suitable habitat for the establishment of several primary-forest trees (e.g., Nectandra spp). Many primary-forest species were found in the fragmented habitats we studied, suggesting that these species are not lost in fragmented landscapes and that plant diversity loss is probably proceeding slowly,. Collectively, riparian strips and isolated trees in a pasture matrix could effectively function as a focus for rainforest regeneration. Riparian strips and frees, therefore, need to be incorporated into landscape designs for maintaining and enhancing ecological diversity.