Wetlands function as carbon sink: Evaluation of few floodplains of middle Assam, northeast India in the perspective of climate change

• Published in: Journal of environmental management 2025-01, Vol.373, p.123841, Article 123841
• Main Authors: Nag, Subir Kumar, Ghosh, Bandana Das, Das, Basanta Kumar, Sarkar, Uttam Kumar
• Format: Article
• Language: English
• Subjects: Assam; Carbon; Carbon - analysis; Carbon Sequestration; Climate Change; Ecosystem; Floodplain wetland; India; Macrophyte; Soil - chemistry; Wetlands
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2024.123841

Floodplain wetlands are biologically rich and productive ecosystems that can capture carbon (C) from the atmosphere through macrophytes and phytoplanktons and hold it in soil for a long time thus playing a critical role in mitigating climate change. The Assam state of India has about 1392 floodplain wetlands engulfing around 100,000 ha area in the Brahmaputra and Barak River basin. In the present study, five different wetlands in the middle Assam viz., 47-Morakolong, Jaliguti, Charan, Chatla, and Urmal were chosen for the estimation of C capture and its storage in soil. The net primary planktonic productivity (NPP) of Chatla was much higher (300mgC/m3/hr) than other wetlands where it ranged around 100–150 mgC/m3/hr. Macrophyte coverage was highest (80%) in Chatla followed by Urmal (50%) and 30% in others. Total organic carbon (TOC) content in water was also significantly higher in Chatla than in others. The C content at different depths of the soil (upper 15 and 15–30 cm) of the wetlands varied widely from 1.3 to 7% and in absolute terms, the total C accumulated in top 30 cm varied from 12.65 to 76.95 MgC/ha. The amount of C in upper 30 cm of corresponding upland sites was estimated to be 8.8–33.62 MgC/ha. Thus, wetlands are superior in terms of C accumulation and storage in their soil compared to the corresponding upland sites. If properly managed, the wetlands can be very effective in capturing and storing C and offset GHG emission and global warming to a great extent. •One of the essential ecosystem services of wetlands is that they act as a carbon sink.•Wetlands generally have a very high carbon sequestering capacity compared to other ecosystems.•We estimated the carbon stock in different wetlands in Assam, a Northwestern state of India, and compared it with reference upland sites.•Various ecological factors affect carbon capture and storage in wetland soils.•Wetlands protection, conservation, and creation are required to combat climate change.