Abstract: A Bayesian probability inversion was applied to estimate the Carbon residence times and sequestration potential of grassland and cropland ecosystems in the Loess Plateau. The result shows that the shortest Carbon residence times ranged from 25 to 203 days were in the aboveground and belowground biomass pools, the metabolic litter pools and the active soil organic matter (SOC) pools, excluding the aboveground biomass pool in cropland. The structure litter pools had Carbon residence times between 2.4 and 3 years. The longest Carbon residence times were 57.4-79.6 years and 593-598 years in the slow and passive SOC pools, respectively. Carbon residences times for the belowground biomass pools were longer in grassland than those in cropland, whereas Carbon residences times in the metabolic litter and slow SOC pools in grassland were shorter than those in cropland. According to the parameters derived from the inversion model, the SOC pools in grassland and cropland would reach a stable state in 250 years. The Carbon sequestration potential would be 3 130 and 2 680 g C·m^-2, respectively, in grassland and cropland ecosystems. The application of manure could result in higher (4 000 g C·m^-2) Carbon sequestration. Compared to that in grassland, the application of manure and the longer Carbon residence times of soil pools could lead to higher SOC sequestration in cropland ecosystem.

Key words: inverse analysis, residence time, carbon sequestration potential