Nesting and nest trees of stingless bees (Apidae: Meliponini) in lowland dipterocarp forests in Sabah, Malaysia, with implications for forest management

Nesting habits of highly social stingless bees (Meliponini) were studied in lowland dipterocarp forests in Sabah, Borneo. A total of 275 nests of 12 species of bees were located. All nests were closely associated with living (91.5%) or dead (8.5%) trees, either within pre-formed cavities in the trunk (cavity nests) or situated in or under the tree base (base nests). Species of bees differed in nesting habit. The majority of species (seven) were cavity nesters, but the majority of nests (81%) were base nests. Nests were often aggregated (mean of 1.94 nests/nest tree), with up to eight colonies and three species in a single tree. Nest trees were mostly large to very large (86.1% above 60 cm dbh) commercial timber trees; 47.3% of nest trees were dipterocarps. According to visual inspection nest trees were of significantly lower expected timber quality then randomly chosen control trees. Taking into account information on tree species, size and expected timber quality, we estimated that 34.0 or 42.6% of nest trees were potential harvest trees, depending on harvesting regulations (reduced impact logging (RIL) versus conventional). Lower percentages under RIL guidelines were mostly due to size restrictions that protect very large trees (>120 cm dbh). Harvesting is likely to kill bee colonies associated with the respective tree. Therefore, and because meliponine colonies are long-lived and have low fecundity, direct impact from logging may have lasting effects on bee populations. Harvesting guidelines that retain high proportions of large and hollow trees should be promoted in order to preserve meliponine pollination in sustainable forest management. (C) 2002 Elsevier Science B.V. All rights reserved.