VEGETATION STRUCTURE AND ENVIRONMENTAL-CONDITIONS OF FOREST EDGES IN PANAMA

Along transects from clearings to the interior of the forest, the greatest change in temperature and relative humidity occurred between 2.5-15 m into the forest. The forest canopy was most open at the clearing-forest border. At the most recently cleared site, this open canopy extended farther into the forest edge than at sites where clearing took place earlier. Density and basalt area of trees (<10 cm diameter at 1.3 m high) were twice as great at the forest edges compared with the interior of forests at the sites where the boundaries were created five to twelve years previously. Floristic composition was unchanged along transects from the forest boundaries to the interior of forests and light-demanding species were not more abundant at forest edges compared with the forest interior. The edge:interior ratio of trees that died after the edges were created was 14:1. Beyond 15-25 m into the forest, neither environmental conditions nor the forest structure and tree mortality were influenced by proximity to the forest boundary. Between 0-15 m, however, vegetation structure changed with both distance from the forest boundary and time elapsed since clearing. -from Author