BIOMASS ACCUMULATION AFTER 10–200 YEARS OF SHIFTING CULTIVATION IN BORNEAN RAIN FOREST

Abstract

I examined the effect of repeated long-fallow shifting cultivation on biomass accumulation in a rain-forest landscape occupied for over 200 years in West Kalimantan, Indonesia. The diameters of stems >5 cm dbh were measured in nine secondary forests using a stratified random design of nested plots (3000 m2 per site). The stands were 9–12 years old and had experienced from 1 to 10 or more cycles of shifting cultivation. Accounting for differences in soil fertility, analysis of covariance (ANCOVA) demonstrated that aboveground live biomass increment (ABI, in megagrams per hectare per year) was significantly greater after four cycles than after six or more cycles. ABI was lowest after two cycles, highest after one or four cycles and intermediate after 6–10 cycles. Differences were driven by the density and biomass of trees >10 cm dbh, which followed a similar pattern. Although the diameter increment and contribution to total biomass of trees >10 cm dbh increased significantly with inherent soil fertility, va...