Carbon Pool Dynamic and Soil Microbial Respiration Affected by Land Use Alteration: A Case Study in Humid Subtropical Area

Alterations of soil characteristics frequently accompany adaptations of pristine areas to different land uses, and these shifts have an impact on the overall ecosystem. Soil carbon stores and atmospheric CO2 emissions are directly affected by those adaptations in farming management and land usage. To comprehend the mechanisms involved in the carbon pool, this study was conducted in a subtropical region by considering six contiguous land uses; pasture, rice land, kiwi orchard, tea land, woodland, and uncultivated land. A CO2 trap was used to quantify CO2 emissions for six weeks, and the obtained data were used to analyze CO2 respiration. In comparison to other land uses, the pasture and woodland showed the best results in soil microbial respiration (SMR), significantly higher than other land uses, with values of 2561.2 and 2334.8 mg CO2-C kg(-1) soil, respectively. Tea land and uncultivated land demonstrated considerably increased microbial metabolic quotients (MMQ) compared to other land uses. Whereas with an increase in soil depth, the MMQ significantly increased in tea and uncultivated lands, other land uses did not show significant changes with depth. Compared to other land uses, pasture, and forest areas boosted soil organic carbon (SOC) and microbial biomass carbon (MBC) both in the top and subsoil. It is reasonable to assume that the amount of SOC and MBC in the soil significantly dropped when the land was converted from pasture and woodland to other land uses.