Allometric equations for estimating above- and belowground biomass in Tea (Camellia sinensis (L.) O. Kuntze) agroforestry system of Barak Valley, Assam, northeast India

Tea (Camellia sinensis (L.) O. Kuntze) agroforestry has widespread implications for the earnings and food security for a large fraction of population in NorthEast India. It also has immense potentiality to act as a considerable reservoir of biomass carbon providing climate change mitigation options. In the present study an attempt was made to develop allometric equations for above- and belowground biomass estimation specific to Tea [C. sinensis (L.) O. Kuntze] in Barak Valley of northeast India. Relationships were developed through destructive sampling and regressing diameter alone and along height, wood density, crown area, branch count with biomass. Allometric power function equation and linear equivalents have been developed. Diameter singly could predict significantly aboveground biomass (AGB) root biomass (BGB) and total Tea biomass (TB) with over 95% accuracy. Whereas incorporation of height, crown area, wood density, branch count with diameter influenced the model in terms of modified coefficient of determination and minimized estimation errors. Branches, stem and leaves accounted 50, 21 and 6% of AGB respectively. Root biomass (BGB) contributed 23% of the total Tea bush biomass. The samples exhibited overall BGB/AGB ratio of 0.30 ± 0.08 and biomass expansion factor (BEF) by 4.23 ± 1.6. Biomass of different components significantly differs in varied diameter sizes.