ARTHROPOD BIODIVERSITY LOSS AND THE TRANSFORMATION OF A TROPICAL AGROECOSYSTEM

The coffee (Coffea arabica) agro-ecosystem in the Central Valley of Co sta Rica was formerly characterized by a high vegetational diversity. This complex system has been undergoing a major transformation to capi tal-intensive monocultural plantations where all shade trees are elimi nated. In this study we examined the pattern of arthropod biodiversity loss associated with this transformation. Canopy arthropods were samp led in three coffee farms: a traditional plantation with many species of shade trees, a moderately shaded plantation with only Erythrina poe ppigeana and coffee, and a coffee monoculture. An insecticidal fogging technique was used to sample both canopy and coffee arthropods. Data are presented on three major taxonomic groups: Coleoptera, non-formici d Hymenoptera, and Formicidae. Data demonstrate that the transformatio n of the coffee agro-ecosystem results in a significant loss of biolog ical diversity of both canopy arthropods as well as arthropods living in coffee bushes. Percentage of species overlap was very small for all comparisons. Furthermore, species' richness on a per tree basis was f ound to be within the same order of magnitude as that reported for tre es in tropical forests. If results presented here are generalizable, t his means that conservation efforts to preserve biological diversity s hould also include traditional agroecosystems as conservation units.