Assessment of Carbon Stock Potential of Arecanut Plantations in Coimbatore District of Tamil Nadu, India

Abstract

Climate change, driven largely by anthropogenic greenhouse gas emissions, demands the identification of sustainable carbon sequestration strategies. Agroforestry systems, particularly plantation crops like arecanut (Areca catechu L.), have gained attention for their potential to serve as carbon sinks while offering socio-economic benefits. Despite widespread arecanut cultivation in India, its role in climate mitigation remains underexplored. This study aims to address the existing knowledge gap by quantifying the biomass and carbon stock of arecanut plantations in the Coimbatore district of Tamil Nadu, India. This study quantifies the biomass and carbon stock potential of arecanut plantations at two managed sites, Onappalayam (Site 1) and Vedapatti (Site 2) in the Coimbatore district of Tamil Nadu, India. Each site comprises a 1-hectare plantation with different intercrops (teak at Site 1 and coconut at Site 2) and crop spacing. Using a standardized quadrat method (25 quadrats per hectare), tree girth measurements were collected to estimate above-ground and below-ground biomass through established allometric equations. To estimate biomass, both above-ground biomass (AGB) and below-ground biomass (BGB) were calculated using standard allometric equations. Total carbon stock was calculated as 50% of the total biomass. Results revealed significantly higher tree density, biomass, and carbon stock at Site 1 compared to Site 2. Site 1 recorded a mean total biomass of 3.04 ± 0.95 tonnes/quadrat and total carbon stock of 1.52 ± 0.48 tonnes/quadrat, while Site 2 reported 1.61 ± 0.52 tonnes/quadrat and 0.80 ± 0.26 tonnes/quadrat, respectively. Differences were attributed to higher tree density and better soil potassium levels at Site 1. Above-ground carbon stock accounted 85% of total carbon, underscoring the dominant role of canopy biomass in carbon sequestration. This study demonstrates that arecanut plantations, beyond their economic value, possess substantial carbon storage potential. Given their long lifespan and adaptability, arecanut systems can contribute meaningfully to climate change mitigation efforts. The findings advocate for their inclusion in agroforestry-based carbon accounting and climate policy frameworks, particularly in tropical regions where such systems are already well established. As global concerns about climate change grow, it becomes increasingly important to recognize the role of agricultural and plantation systems in climate mitigation strategies. This study underscores the contribution of arecanut plantations to carbon sequestration and advocates for their integration into broader agroforestry systems. When managed sustainably, these plantations offer multiple benefits: they not only absorb atmospheric carbon but also improve soil quality, and provide steady income to farmers.