SINGLE-TREE SELECTION SILVICULTURE AFFECTS CAVITY RESOURCES IN MIXED DECIDUOUS FORESTS IN THAILAND

Thailand's forest ecosystems contain a diverse vertebrate fauna and >3 0% of the species are thought to use cavities in trees. Forest managem ent practices may significantly alter cavity availability for hole-nes ting vertebrates. The effects of single-tree selection systems, common ly used in Thailand, on tree cavity abundance have not been extensivel y studied in any forest ecosystem, and no studies have been conducted in Thailand. We measured the effects of single-tree selection harvest on cavity availability in mixed deciduous forests. We compared tree an d cavity densities in unlogged and logged forests (5 stands in each ty pe) in Huai Kha Khaeng Wildlife Sanctuary (HKKWS) in western Thailand. Tree densities (t = 2.89, 8 df, P = 0.02), cavity-tree densities (t = 4.27, 8 df, P = 0.003), and cavity densities (t = 4.44, 8 df, P = 0.0 04) were greater in unlogged than in logged stands. Ninety-two percent of cavity trees were alive; dead trees were uncommon, probably becaus e of annual ground fires. Alangium salviifolium, Lagerstroemia spp., a nd Vitex spp. were the taxa most likely to form cavities, accounting f or >30% of all trees and 66% of the cavities in unlogged habitats. Log ging reduced tree densities of Vitex spp., but did not affect tree den sities of Lagerstroemia spp. or A. salviifolium, nor cavity densities in Lagerstroemia spp, and Vitex spp. However, logging reduced cavity d ensities in A. salviifolium. Single-tree selection cutting reduced cav ity abundances in these mixed deciduous forests. Maintenance of cavity -forming species and leaving more large-diameter trees may be required to maintain habitat for cavity-dependent wildlife.