THE IMPACT OF FOREST SUCCESSIONAL STATUS ON COMMUNITY STRUCTURE OF NEOTROPICAL CERAMBYCID BEETLES

Due to anthropogenic activities, tropical rain forests face many challenges in sustaining biodiversity and maintaining global climates. This project examines how forest successional status affects community composition of saproxylic cerambycids, which, as early colonists of moribund trees, have an important role in nutrient cycling. In the lowland rain forest of Costa Rica, thirty-nine trees in five plant families (Fabaceae, Lecythidaceae, Malvaceae, Moraceae, and Sapotaceae) were sampled in a mosaic of old growth and secondary forest. They yielded 3545 cerambycid individuals in 49 species. Species richness was almost identical in old growth and secondary forest; but abundance was higher in old-growth. This was largely because several cerambycid species, which appear to be both host and old-growth forest specialists, reached high densities within old-growth forest patches but seldom colonized apparently suitable trees within secondary forest. Overall, community structure was most strongly influenced by host plant species; within most plant families it was also impacted by forest structure. Moraceae was the exception, presumably because the focal tree species was abundant in both old-growth and secondary forest. This study suggests that even small areas of old growth forest can act as refuges for specialized forest species, but that secondary forest may inhibit dispersal. The vulnerability of specialized saproxylic insects to land use change will be linked to the ability of their preferred host trees to disperse to and persist in disturbed habitats