An overview of Allometric Equations Used for Biomass Estimation in Nepal

Estimation of biomass is an important tool in the management of different types of natural forests and plantations in Nepal. It is essential to estimate growing stock (biomass) in a particular area for better management of government-managed forest, private forest and community forests through the use of reliable allometric equations. The importance in producing allometric equations for biomass estimation of tree components for fuel wood and fodder has increased due to assessment of forest carbon in recent years in Nepal. The existing tree-wise allometric equations developed for predicting biomass of tree components are for a fewer number of species. Very few organisations have been involved in biomass studies. Mostly, the equation Ln (W) = a + b Ln DBH (W refers to green or oven-dry weight of tree components in kg and DBH refers to over bark diameter at breast height in cm measured at 1.3m or 1.37 m) has been used for estimation of above-ground biomass for 46 tree and NTFP species in the Terai, Siwalik and Mid-hills of Nepal. The biomass studies have been carried out for three mixed species in the Mid-hills and two 2 mixed species in the Terai. The equation, Ln (W) = a+b Ln (D² L) has been developed for estimation of foliage, branch and culms of four bamboo species (Bambusa nutans sub sp. nutans, B. nutanssub sp. cupulata, B. tulda and Dendrocalamus hookeri) in the Terai region of Nepal. These equations for biomass prediction are available for predicting the aboveground tree components (stem, branch, and foliage in most cases) and only for some of the major tree species. There are no equations or models for predicting the below-ground-components of tree biomass (stump and ischolar_main) in Nepal. The existing allometric equations for estimation of biomass have been developed from a narrow geographical area and small-sized trees in most cases, which has caused the limited use of such equations. Gaps and shortcomings related to developed allometric equations are discussed. Sound government plan and support, amendment in existing rules and regulations, strong coordination among the institutions (government, non-government and private), and use of standard manuals are some of the major future priorities to carry out above-ground and below-ground biomasses in Nepal