<S1-7> Allometric equations for accurate estimation of forest biomass in tropical logged-over and early successional secondary forests in Sarawak, Malaysia

Abstract

Accurate estimation of biomass in tropical forests is essential to evaluate the base line for nations' carbon storage on the REDD+ scheme. Presently, allometric equations derived from tropical primary forest trees are usually used to estimate the forest biomass of different forest types, such as primary, logged-over and early successional secondary forests. However, it is uncertain whether these previously developed allometric equations are appropriate for biomass estimation on logged-over and early successional secondary forests, because those forests consist of significantly different species with different structural traits, such as lower wood density compared to primary forest trees, and these traits are generally related to different coefficients of the equations. In this study, we 1) developed allometric equations for logged-over and early successional forests in Sarawak, Malaysia and 2) compared various allometric equations, including those for primary and secondary forests, to evaluate the adequacy of biomass estimation for studied forests. We found that allometric equations developed for the two forest types significantly differ from that for the primary forests and even that for the pan-tropic general models. Moreover, below-ground equations for early successional forest also showed significantly lower biomass estimation than those for primary forest. Therefore, the choice of the biomass estimation models for the tropical logged-over and early successional secondary forests requires careful consideration of their suitability.