The Importance of Primary Tropical Rain Forest For Species Diversity: An Investigation Using Arboreal Ants as an example

The arboreal ant communities of a primary lowland rain forest and three differently disturbed forests that lie close together forming an anthropogenic disturbance gradient were collected with insecticide fogging. Combined samples from all trees (87 foggings) comprised 153,504 ants sorted to 331 morphospecies. The primary forest ant fauna was characterized by high species richness and 53 foggings were necessary to collect communities representatively. Another 63 species of ants were found in the disturbed forests indicating a large regional species pool that might exceed 420 species of arboreal ants. Anthropogenic disturbance caused a change in the taxonomic composition, diversity and structure of ant communities. Community size was a predictor of species richness in the severely disturbed forest types but not in the old secondary or primary forest. Ant abundance had declined significantly in the disturbed forests and only 10% of the primary forest’s species were collected in the most disturbed forest type. In each of the secondary forests a change in the frequency distribution of species was observed and a small number of species had gained numerical dominance. Analysis of species associations indicates that the strength of species interactions changed with the degree of forest disturbance. These changes were still clearly recognizable after 40 years of forest regeneration despite optimal conditions for colonization from the adjacent primary forest, demonstrating that the time scale needed for forest recovery after anthropogenic disturbance is very long.