Biomass models for estimating carbon storage in Areca palm plantations

Globally, similar to 0.8 million (M) ha of land is under Areca palm (Areca catechu) plantations with annual nut production of 1.0 M mega grams (Mg). Areca (also called betel nut) has been principally managed in plantations for commercial nut production and a primary source of income for similar to 16 million people in India. A substantial portion of betel nut plantations has been developed by converting natural forests. Although Areca has vast geographical distribution with economic importance, little has been studied on its role in biomass carbon management. Therefore, the present study aims (i) to develop biomass estimation models for Areca, and (ii) to estimate biomass storage and changes in carbon stock along a chronosequence of Areca plantations. The mean aboveground and total biomass across all height classes ranged from 4 to 56 and 5-75 kg plant(-1), respectively. Among the biomass models compared, the model that contained both plant height (H) and diameter at breast height (D) as predictor variables was the top ranked for predicting total plant biomass. The estimated total biomass carbon stocks were 7.8, 18.4, 20.5 and 20.5 Mg ha(-1) in 10, 15, 25, and 35 yr old plantations, respectively. The biomass carbon accumulation rate ranged between 0.59 Mg ha(-1) yr(-1) in 35 yr old plantations and 1.22 Mg ha(-1) yr(-1) in 15 yr old plantations. Due to their low biomass carbon storage and other associated ecosystem disservices, monoculture palm plantations play a minimal role in sustainable land management and climate change mitigation in our study area. We recommend Areca polycultures and the integration of agroforestry practices in existing monoculture Areca plantations to maintain environmental sustainability.