Role of Tropical Floodplain Wetlands in Carbon Sequestration: A Case Study from Barak River Basin of Assam, Northeast India

Abstract

Wetlands store an enormous amount of carbon in its different biophysical components, namely vegetation, soil, and sediment, thus playing an important role in mitigating climate change. Floodplain wetlands cover substantial area in northeast India. They are seasonally inundated by nutrient-rich floodwater that facilitates luxuriant growth of shrubs, herbs, and pteridophytes. High productivity and rapid turnover of such plants may play an important role in carbon-stocking and sequestration in such wetlands. We tested this proposition in Chatla, a seasonal floodplain wetland in Assam, Northeast India by estimating the carbon stock and sequestration of vegetation and soil. The estimated total carbon stock was 21.75 Mg C ha−1. Of this, the vegetation component contributed 3.18 Mg C ha−1 (14.62%), saturated soil contributed 8.53 Mg C ha−1 (39.22%), and unsaturated soil contributed 10.04 Mg C ha−1 (46.16%). The carbon sequestration potential of Chatla was estimated to be 6.36 Mg C ha−1 year−1, of which the contribution of vegetation was the highest (4.14 Mg C ha−1 year−1), followed by saturated soil (1.76 Mg C ha−1 year−1), and unsaturated soil (0.46 Mg C ha−1 year−1). Thus, it is evident that tropical floodplain wetlands sequester large amount of carbon annually through its biophysical components, i.e., vegetation especially the lower angiosperms like shrubs and herbs, and soil. Therefore, management strategies should focus on maintaining vegetation cover comprising the lower angiosperms in the wetland.