Linking biodiversity and carbon stocks in homegardens across an elevational gradient in Nagaland, Northeast India

Abstract

Homegardens are multifunctional agroforestry systems that support rural livelihoods while conserving biodiversity and storing ecosystem carbon. However, the relative influence of biodiversity, vegetation structure, and elevation on carbon storage in tropical homegardens remains poorly understood. This study evaluated species diversity, vegetation structure, biomass carbon, soil organic carbon (SOC) stock, and their interrelationships across three elevational zones (E1: < 250 m a.s.l.; E2: 250–500 m a.s.l.; E3: >500 m a.s.l.) in subtropical homegardens of Nagaland, Northeast India. A total of 130 plant species were recorded from 54 homegardens. Homegarden size declined significantly with elevation, whereas species richness and evenness increased without significant changes in overall species diversity. Aboveground biomass (AGB) and aboveground biomass carbon (AGBC) showed no significant differences among elevational zones, whereas SOC stock increased significantly with elevation. Species richness was positively associated with AGBC and SOC stock, whereas homegarden area showed negative relationships with species richness, species evenness, and carbon variables. Multiple linear regression analysis further revealed that homegarden area was significantly associated with AGBC, whereas elevation and species richness were significant predictors of SOC stock. Overall, traditional homegardens of Nagaland function as important reservoirs of biodiversity and carbon, highlighting their value for climate change mitigation, sustainable land management, and rural livelihood security.