Oligochaetes in fire climax grassland and conifer plantations in Papua New Guinea

Earthworm populations in grassland and plantations in the area of Bulolo, Papua New Guinea were compared with populations in nearby undisturbed rain forest. The grasslands had been maintained by burning for many years. The Pinus plantation had been developed on a burned grassland site and the Araucaria plantation on a site which had been cleared of secondary forest. The grasslands and the Pinus plantation supported moderate populations of exotic earthworms including Pontoscolex corethrurus, but no indigenous species. The Araucaria site supported a native species, Amynthas zebrus only, which was also found together with two other native species at very low density in rain forest. Exotic earthworm species widespread throughout the tropics, were present in disturbed soils and formed moderately high density populations in burned grasslands. There was no evidence that they displaced native Megascolecidae in rain forest.