Ecological succession in new and old swiddens of montane Papua New Guinea

Fieldwork conducted in new and old swiddens in the Maring territory of the Bismarck Mountains of Papua New Guinea indicated a successional sequence of crop composition, diversity, and biomass regulated by human and ecological processes. With increasing swidden age, the number of cultivated species, individuals, varieties, and net productivity decreased. In contrast to new swiddens, old swiddens were characterized by a simplified crop composition and a distinct vertical stratification. While a 3-month-old garden contained 10 cultivar species, 43.5 plantings of taro, a cultivar biomass content of 2.54 kg/25 m², and a net productivity of 1.13 gm/m²/day, a 2-year-old garden contained six cultivar species, no taro plantings, a cultivar biomass content of 13.80 kg/25 m², and a net productivity of 0.77 gm/m²/day. Differences in the life histories of cultivars help determine cultivar succession. This study quantitatively defines these changing characteristics of old and new swiddens. It concludes that the Kauwatyi system of subsistence, which emphasizes diversity and conservation practices, such as the planting and protection of certain forest regrowth species, ensures the regeneration of forest.