Spatiotemporal Variability of Soil Organic Carbon Content Over India Based on an Ecosystem Model and Regional Databases

摘要

A study on spatiotemporal variability of soil organic carbon content (SOC) over India is carried out based on a remote sensing data-driven terrestrial ecosystem model and the regional databases. The model is initialized with the equilibrated solutions corresponding to undisturbed balanced biosphere condition and then marched forward with realistic forcing for the recent decades. Both the model solution and regional data show a good agreement between them with a large SOC values with mean 12 kg m(-2) for the forest and cropland-dominated regions, a moderate value (8 kg m(-2)) for the mixed shrub and grassland, and small for the grassland regions (4 kg m(-2)) correspondingly for 30 m upper active layer of the soil. The model SOC shows a significant seasonal variability across all the vegetation types with peak value during spring season (March-April) and trough during the autumn (September-October). The SOC budget of the country is around 13 Pg for the top active layer of the soil. It has shown a significant increasing trend of 22 Tg year(-1) for the study period resulted from the positive growth rate of 25 Tg year(-1) for the cropland and negative growth rate of 3 Tg year(-1) for the forest region. The extrapolated annual national SOC budget is 25 Pg correspondingly for 1 m depth soil layer.