Plant biodiversity and carbon sequestration potential of the planted forest in Brahmaputra flood plains

Abstract

Globally, while experts debated whether planted forests (PF) restore biodiversity or create biological deserts, their potential role in mitigating climate change is mostly overlooked. In this study, we investigated the long-term impact of PF on the species composition, plant diversity, biomass stock, and carbon (C) storage potential in the Brahmaputra flood plain of North-East India. The phytosociological study was conducted using a modified Gentry plot method and species-specific allometric models were used to estimate biomass stock in the 39-year old PF and equivalent age of natural forest (NF). We identified 57 trees, 22 shrubs, and 23 herb species in the PF, and 54 trees, 17 shrubs, and 8 herb species in the NF. Species richness and biodiversity indices showed greater values in PF whereas species dominance and evenness were higher in NF. After 39-year of plantation, total biomass C was estimated at 165 Mg C ha^-1 in PF and 197 Mg C ha^-1 in equivalent age of NF. Bombax ceiba, Dalbergia sissoo, Samanea saman, Tetrameles nodiflora, and Gmelina arborea were the dominant tree species that contribute 56% of the total biomass C in the PF. The ecosystem carbon pool (plant biomass + deadwood + litter + SOC) was 17% higher in NF and showed the greater potential of carbon dioxide sequestration (959 Mg CO₂ ha^-1) compared to the PF (818 Mg CO₂ ha^-1). Our study suggested PF in flood plain degraded lands can act as a major C sink and stored a substantial amount of carbon dioxide after 39-year of the plantation. It is concluded that PF can be a preferable ecosystem management tool to fulfill the objectives of biodiversity conservation and provisioning climate services like C sequestration.

Keywords: Biomass; Carbon storage; Climate regulating services; Ecosystem C pool; SOC stock.