PARENT SESSION
Poster Session #44: Plant Ecology II.
Friday, August 10, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
Edge effects in a forest mosaic: forest structure and composition in the Highlands of Chiapas, Mexico.
Lopez-Barrera, Fabiola1, 1
ABSTRACT- Forest edges created by scattered-patch clear-cutting have become a common landscape feature in Tropical cloud montane forest. As part of a larger study about edge structure and edge permeability a study was carried in the highlands of Chiapas, Mexico in order to assess changes in vegetation structure and floristic composition along a gradient from the interior forest into adjacent clearings. At nine sites a 80 x 10 m belt transect was established perpendicular to the forest/pasture edge. Plant species presence was recorded and seedling, sapling and tree stem diameter and height were assessed. A single-factor (distance) analysis of variance showed no significant difference from the forest interior towards the edge in plant density and basal area (P>0.05). Richness and floristic composition did not vary with the depth-of-edge influence (Chi-square tests, P>0.05). The level of disturbance may be influencing the response of the vegetation to the edge to interior gradient, and hence the observed results can be explained by the interaction of low-human disturbance and fragmentation. Abandoned grasslands showed the presence of patches of secondary shrub vegetation and recovering forest (pine and oak seedlings) at 20 m into the grassland. Expected spatio-temporal changes include the evenness of the forest/grassland edge as time advances. Edge effects on vegetation are not measurable with conventional methods were forests are mosaics with small clearings (0.5- 1 ha) and widespread low-human disturbance.
KEY WORDS: Tropical Cloud Montane Forest, Edge structure, Oak Regeneration