Rebecca Ryan
Department of Biology, Carleton College, Northfield, MN, USA 55057
Abstract. Edges effects can cause a number of changes on plant and animal distributions as well as patterns of soil moisture. In 1993, Sendero Tres Rios (STR), a trail in La Selva, Costa Rica, was widened to a total of 6m and paved. I explored the possibility that the widening of STR created an edge. The tropical climbing vine Monstera tenuis was studied to investigate this question because the vine tends to orient itself on the part of the tree that is exposed to the greatest amount of light. The orientation of growth at 1.5m from the ground (breast height) of M. tenuis was measured in relation to the trail. The sites studied were an edge, STR, and a typical 2m trail, Sendero Sabalo-Esquina, SSE. There was a significant difference in the orientation of growth of M. tenuis between SSE and the edge. STR and the edge were not significantly different from one another. However, the mean orientation of growth for SSE and STR was not significantly different, but this lack of significance was marginal. In other words, STR is receiving enough light due to a gap created by the trail that the orientation of M. tenuis is being effected. The result is that vines on STR are growing in an orientation similar to that found at an edge indicating that the widening of STR has indeed created an edge.