Effects of Forest Fragmentation on Dung and Carrion Beetle Communities in Central Amazonia

Abstract

This study, one of the first to document the effects of forest fragmentation on insects in the tropics, showed that dung and carrion beetle communities in 1—ha and 10—ha forest fragments differed from those in contiguous forest, even though the fragments had been isolated by <350 m for an ecologically short time (2—6 yr). During 288 pitfall trap days at the Minimum Critical Size of Ecosystems study site 80 km north of Manaus, Brazil, I captured 55 species in 15 genera. Trap days were divided equally between three 1—ha, three 10—ha, three clear—cut, and three contiguous forest areas. Pitfall samples from clear—cut areas separating forest fragments from intact forest indicated that beetles rarely moved from intact forest into fragments. The apparent barrier imposed by clearcuts diminished with the invasion of second growth. Except for the four species in the genus Glaphyrocanthon, all species were found more frequently in forested areas than in clearcuts. Glaphyrocanthon constituted 97% of the 717 individuals captured in clearcuts and was never captured in contiguous forest or 10—ha fragments. Forest fragments had fewer species, sparser populations, and smaller beetles than comparable intact forest areas. The changes in dung and carrion beetle communities help explain the low rates at which dung decomposed in 1—ha fragments. Thus, forest fragmentation not only changes the dung and carrion beetle fauna; its effects ramify through other related community and ecosystem processes, as well.