Carbon sequestration potential and CO2 fluxes in a tropical forest ecosystem

Abstract

Carbon (C) is a key product of forests, but not widely studied for available C stock, and biomass of tree species in typical forest ecosystems of India. Therefore, it is useful to estimate C stock at national and regional levels for establishing forest-based policies and developing roadmap for long-term plans and strategies to reduce the rate of increase of atmospheric carbon dioxide (CO2). Hence, present investigation was conducted to assess C storage and CO2 fluxes in tropical dry deciduous forest ecosystems of Jhumpa and Kairu in the southern Haryana, India. The C stock of trees in above ground biomass (AGB) was calculated by assuming the C content at 50% of the total biomass. Concentration of C in composite samples of shoots and roots of shrubs and herbs was estimated by the ash method. Soil C storage was determined on the basis of C concentration and soil bulk density up to 60 cm depth. The AGB of trees ranged from 33.1 to 75.8 Mg ha−1; the belowground biomass from 9.0 to 18.5 Mg ha−1 and total plant C storage from 24.3 to 53.9 Mg C ha−1. The total biomass of shrubs was 16.2 Mg ha−1 for the Salvadora oleoides forest at Jhumpa compared with 8.4 Mg ha−1 for the Acacia senegal-Acacia tortilis forest at Kairu. Net primary productivity of various components of trees in these forest ecosystems ranged from 8.1 to 9.6 Mg ha−1 y−1 and net flux of C from 4.6 to 5.8 Mg C ha−1 y−1. The annual litter fall in two forest ecosystems ranged from 3356 to 4498 Kg ha−1. S. oleoides contributed 50.0% and 47.3% towards the above ground and below ground C pools corresponding to the 17.9 Mg C ha−1and 4.1 Mg C ha−1, respectively. S. oleoides played a dominant role in biomass production and C assimilation in S. oleoides-A. tortilis forest at Jhumpa, while Prosopis juliflora and A. senegal were the highest contributors in A. senegal-A. tortilis forest at Kairu because of a high girth class and high density of trees, respectively. The cumulative soil organic carbon (SOC) stock up to 60 cm depth was more in A. senegal-A. tortilis forest at Kairu (16.3 Mg C ha−1) than that in the SO-AT forest at Jhumpa (12.9 Mg C ha−1). The results of this study revealed that S. oleoides and P. juliflora are key species as they sequester more C under a range of disturbances. Carbon sequestration potential of the studied forest ecosystems was 3.55 to 4.35 Mg C ha−1 y−1 which indicates a high C sequestration potential of these ecosystems.