Impact of logging on aboveground biomass stocks in lowland rain forest, Papua New Guinea

Abstract

Greenhouse-gas emissions resulting from logging are poorly quantified across the tropics. There is a need for robust measurement of rain forest biomass and the impacts of logging from which carbon losses can be reliably estimated at regional and global scales. We used a modified Bitterlich plotless technique to measure aboveground live biomass at six unlogged and six logged rain forest areas (coupes) across two ∼3000-ha regions at the Makapa concession in lowland Papua New Guinea. "Reduced-impact logging" is practiced at Makapa. We found the mean unlogged aboveground biomass in the two regions to be 192.96±6 4.44 Mg/ha and 252.92±6 7.00 Mg/ha (mean±6 SE), which was reduced by logging to 146.92±6 4.58 Mg/ha and 158.84±6 4.16, respectively. Killed biomass was not a fixed proportion, but varied with unlogged biomass, with 24% killed in the lower-biomass region, and 37% in the higherbiomass region. Across the two regions logging resulted in a mean aboveground carbon loss of 35±6 2.8 Mg/ha. The plotless technique proved efficient at estimating mean aboveground biomass and logging damage. We conclude that substantial bias is likely to occur within biomass estimates derived from single unreplicated plots. Show more