Distribution of Ground-dwelling Arthropods in Tropical Countryside Habitats

Abstract

The future of biodiversity depends to a great extent on the conservation value of human-dominated and seminatural habitats. In a mixed agricultural landscape in southern Costa Rica, we compared the richness and composition of terrestrial arthropod communities occurring in three habitat types along a gradient of increasing disturbance: in a large (227 ha) forest fragment, small (3.8–5.3 ha) forest fragments, and sun coffee ( 1–3h a) plantations. Pitfall trap sampling revealed decreasing morphospecies richness with increasing disturbance. Moreover, the number of species unique to a habitat type was lower in the smaller forest fragments and the coffee sites. We found significant changes in community composition associated with habitat at the levels of order (all arthropods), family (beetles), and morphospecies (carabids, scarabs, and ants). We identified no significant correlation of richness among the taxonomic orders, meaning these taxa are unable to serve as biodiversity indicators (for each other or for all arthropods) in the study region. Arthropod diversity presently found in countryside habitats is certainly lower, and perhaps less sustainable, than that of the extensive forested habitats fragmented > 40 years ago. It nonetheless remains substantial, suggesting a conservation opportunity in human-dominated landscapes of the tropics.