Changes in the Seasonal Cycle of Carbon Stocks and Fluxes Due to Fires in the Grassland Ecosystem of Manipur, North East India

Fire is a common perturbation in the grassland ecosystems throughout the world. Effect of fire on carbon stock, rate of C-accumulation and soil CO₂ flux have been studied in Imperata cylindrica-Sporobolus indicus-dominated grassland community of Manipur, Northeast India. Carbon stock in the vegetation components was estimated to be 12.59 and 12.06 Mg ha^-1 and soil organic carbon stock was found to be 57.28 and 44.74 Mg ha^-1 in the control and burnt site respectively. It indicates that fire decreases the carbon stock in the grassland. However in the following year the annual rate of carbon accumulation increased in burnt site (7.94 Mg ha^-1 year^-1) compared to the control site (6.75 Mg ha^-1 year^-1) whereas the annual soil CO₂ flux decreased in the burnt site (4.06 Mg ha^-1 year^-1) in comparison to the control site (7.26 Mg ha^-1 year^-1). Our estimates of carbon budget reveal that the net uptake was 3.88 Mg C ha^-1 year^-1 in the grassland ecosystem after the burning treatment. Thus, the annual burning of grassland can cause major changes to carbon stocks and fluxes.