Abstract # 2640 Event # 125:

Scheduled for Sunday, September 20, 2009 03:15 PM-03:25 PM: Session 13 (Del Mar Room) Oral Presentation


T. Steffens, K. McGoogan and S. Lehman
University of Toronto, Toronto, ON, Canada

Over the course of 14 months we assessed the impact of edge effects on the distribution of Propithecus coquereli groups in Ankarafantsika National Park, Madagascar. The term “edge effects” refers to how abiotic and/or biotic conditions interact between two adjacent habitats separated by an abrupt habitat boundary. In Ankarafantsika the edge occurred between tropical dry forest (habitat) and savannah (non-habitat). To assess the edge effect we placed two 1250m transects into the forest habitat perpendicular from the edge. Transect 1 and 2 were walked 22 and 20 times respectively. Along each transect we measured abiotic (temperature, wind speed, light penetration, and humidity) and biotic variables (stem density, basal area, and tree height). To determine the distribution of groups we mapped all group sightings recorded along each transect and within the study site trail systems. We recorded a total of 156 group sightings within the entire study area trail network (25.26km). We found that temperature, wind, and light penetration decreased from the edge to the interior and humidity increased. All biotic variables increased with distance from the edge. Randomization models of spatial edge patterns indicate that the depth of edge impact reaches 500m. We recorded 4 group sightings in the edge habitat and 152 in the interior. Based on group distribution within the study site, P. coquereli appears to avoid the edge.