Woody and Scandent Plants on the Edges of an Andean Timberline

Abstract

YOUNG, KENNETH R. (Department of Geography, University of Colorado, Boulder, CO 80309). Woody and scandent plants on the edges of an Andean timberline. Bull. Torrey Bot. Club 120: 1-18. 1993. -The structure and composition of forest edges were examined in the timberline zone of Rio Abiseo National Park in north-central Peru. Tree, shrub, and scandent plant species were inventoried in six 25 by 40 m forest plots, positioned with the long axes perpendicular to the forest-grassland boundary, and located at different elevations. Number of tree and shrub species on the 0.1 ha plots decreased from 30 to 12 (lower to higher elevation) over the 250 m elevational gradient studied; at lower elevations (3300-3350 m), there were more habitat specialists, i.e., species apparently restricted to either forest edge or forest interior. In all plots, scandent plant species were diverse (12-20 species/0. 1 ha) and abundant (at total densities of 6000-10,000 stems/ha). Many were scandent by virtue of the angles formed by leaves and/or branches; none could be classified as forest-edge or -interior specialists. Forest margins were variably affected by occasional stand-destroying fires originating in the grasslands. The specifics of forest composition and structure in the timberline zone were influenced by elevation, distance from the edge, and the nature and intensity of past disturbances.