This study was designed to determine the extent that trail maintenance and associated human derived disturbance impacts the understory floral diversity and floral populations of protected areas of tropical rainforests. Five national parks and private reserves were sampled representing different ecosystems in the rainforests of Costa Rica. Five to eleven sites per park were sampled. Light quality, soil characteristics, total number of plants and total number of different plants were determined at each sample site at three locations: along trails (0), 2 meters off trails (2), and 4 meters off trails (4). All plants at each location were described, tabulated on data sheets, photographed, and videotaped. The relative level of disturbance was assessed by dividing the total number of different plants at each location within a site by the total number of plants present. This results in a fraction between 0 and 1 that we refer to as the biodiversity index (BDI). Results of intrasite analysis indicate that BDI is significantly different between 0 and 4 meter locations along the trails of three of the five parks sampled, with higher numbers of total plants but lower numbers of different plants at 0 compared to 4. Park to park comparisons indicate that the total number of plants and the total number of different species present per location within each site is strongly correlated to ecosystem type. We conclude that the establishment of trails has a measurable effect on the vegetative community through which it passes. In addition, the level of disturbance and the distance from the trail that this disturbance significantly impacts the floral community is influenced by the volume of annual human activity, the type of ecosystem, and whether the ecosystem is primary or secondary growth flora.

Key words: Biodiversity Ecotourism Rainforests