Diversity and Organization of the Ground Foraging Ant Faunas of Forest, Grassland and Tree Crops in Papua New Guinea.

Abstract

Thirty samples of ants were taken in each of seven habitats: primary forest, rubber plantation, coffee plantation, oilpalm plantation, kunai grassland, eucalypt savannah and urban grassland. Sixty samples were taken in cocoa plantations. A total of 156 species was taken, and the frequency of occurrence of each in each habitat is given. Eight stenoecious species are suggested as habitat indicators. Habitats fell into a series according to the similarity of their ant faunas: forest, rubber and coffee, cocoa and oilpalm, kunai and savannah, urban. This series represents an artificial, discontinuous succession from a complex stable ecosystem to a simple unstable one. Availability of species suitably preadapted to occupy habitats did not appear to limit species richness. Habitat heterogeneity and stability as affected by human interference did seem to account for inter-habitat variability in species richness. Species diversity was compared between habitats using four indices: Fisher et al.; Margalef; Shannon; Brillouin. Correlation of diversity index with habitat heterogeneity plus stability was good for the first two, moderate for Shannon, and poor for Brillouin. Greatest diversity was found in rubber, the penultimate in the series of habitats according to heterogeneity plus stability ('maturity'). Equitability exceeded the presumed maximum in rubber, and was close to the maximum in all habitats. The mosaic dispersion pattern found among ants elsewhere also appeared to be present in each habitat. The mean maximum number of territories possible to be overlapping is about 4.6; the number in a particular case probably being a function of the specialization of the dominant ant present. Ecological isolating mechanisms among ants are probably similar to those among birds; size and structure of mouthparts in ant communities warrant further study.