Estimation of the Spatiotemporal Patterns of Vegetation and Associated Ecosystem Services in a Bornean Montane Zone Using Three Shifting-Cultivation Scenarios

Abstract

Tropical countries are now facing increasing global pressure to conserve tropical forests, while having to maintain cultivated lands (particularly shifting cultivation) for the subsistence of local people. To accomplish the effective conservation of tropical forests in harmony with subsistence shifting cultivation, we evaluated the influence of shifting cultivation on ecosystem services (i.e., biodiversity and carbon stock) at a landscape level based on three land-use scenarios. The study focus was the upland area between the Kinabalu Park and the Crocker Range Park in Sabah, northern Borneo, where local people conduct shifting cultivation for their subsistence. In this area, vegetation patches of various stages of secondary succession admix with shifting-cultivation lands. An earlier study in the same site depicted significant relationships between the stand ages of vegetation patches (which form a sere of secondary succession after the abandonment of cultivated land) and the above-ground biomass (i.e., carbon stock) and species composition of the stands. We incorporated these significant relationships to a stand-age estimation algorithm that had been developed earlier. We first mapped current (as of 2010) spatial patterns of the above-ground biomass and plant-community composition for the whole landscape. Subsequently, we simulated the spatiotemporal patterns of the above-ground biomass and plant-community distribution using three land-use scenarios: (1) reducing the area of shifting cultivation by one half and protecting the rest of the area; (2) shortening the minimum fallow period from 7 to 4 years while maintaining the same area of cultivation; and (3) elongating the minimum fallow period from 7 to 10 years while maintaining the same area of cultivation. Results indicated that land use based on scenario 2 could increase the carbon stock while maintaining the cultivation area. Our methods were effective in mapping the structure and composition of highly dynamic forests at a landscape level, and at predicting the future patterns of important ecosystem services based on land-use scenarios.