Changes in Arboreal Arthropod Communities Along a Disturbance Gradient

Abstract

Arboreal arthropod communities in four forests along an anthropogenic disturbance gradient in Malaysia were sampled by fogging and changes at the ordinal level were analyzed. At least ten individuals of a single tree species from each forest type were fogged. These were two species of Euphorbiaceae from the primary forest and from the most disturbed forest, and a species of Verbenaceae in the two other secondary forests. The high constancy and low variance of the relative proportions of taxa in the crown communities found in primary rain forests was lost in the disturbed forests. Anthropogenic disturbances (e.g., extended clearings) led to fluctuations in rank abundances of taxa. The Formicidae lost their dominant rank in the most disturbed forest while Lepidoptera larvae, which were always rare in the primary forests, reached high abundances. During forest succession, the composition of taxa in the communities converged to the conditions of the primary forests. Short term colonization processes, which were investigated in every type of forest by carrying out five daily consecutive foggings of an individual tree, always displayed great variability. Coleoptera and Diptera, in addition to non-formicid Hymenoptera in the five-year-old forest, were dominant. During all daily foggings it was unforeseeable which group would be present in high numbers. This leads us to suppose that particularly strong stochastic influences are in effect during short term colonization.