吉林西部盐碱草地土壤固碳潜力及其稳定机制研究

Conservative management could enhance the soil carbon storage from atmospheric CO2. Different managements differed in carbon sequestration rate which caused a different pathway approaching to the saturated soil carbon capacity. The different between saturated soil carbon capacity and the current sol carbon capacity was defined as the soil carbon sequestration potential, which could be fulfilled by preserved activities. The saline-alkaline grassland distributed in the west of Jinlin province was managed by diversiform conservative activities, which complicated the estimation of regional carbon sequestration potential. Furthermore, the drying-wetting cycle in growing season and freeze-thawing cycle in off-season varied with the changing rainfall size regime and snow coverage. The physical and chemical protection of soil organic carbon could maintain a higher soil carbon capacity, and formed an immobilized soil carbon stock. In this study, we combine the field sampling and lab simulation to detect a suite of soil physical properties and chemical properties determining the soil carbon turnover and immobilization. Meanwhile, vegetation productivity and microorganism productivity concerning carbon input were also observed. We aim to clarify the carbon turnover mechanism subjecting to anthropogenic activities. Nevertheless, we also performed a freeze-thawing cycle simulation experiment to raveling the outcomes of off-season climate change on carbon turnover. Regional management area, management pathway and management duration were archived to build up a database for the calculation of regional carbon sequestration potential. Finally, the regional carbon sequestration potential and its stabilization mechanisms could be illustrated.

草地土壤碳库是陆地土壤碳库的重要组分，受人为活动和气候变化的影响，其固碳容量逐渐降低。保护性管理措施可以增加土壤固碳速率和土壤固碳容量。草地管理还会影响土壤水热状况，尤其是对干湿交替和冻融循环的影响，同时改变影响土壤碳输入和周转的生物因子。土壤固碳容量在气候变化和任务活动影响下的稳定受一系列周转、保护和分解机制等的影响。本研究选取我国农牧交错带东缘的吉林西部盐碱草地，采用空间代替时间方法估算保护管理措施影响下盐碱草地土壤固碳速率趋势和固碳潜力变化。本研究分析多年气象数据，监测野外干湿交替和冻融循环，结合草地管理改变的碳输入及碳周转因子观测揭示干湿交替和冻融作用影响土壤有机质周转和稳定的机制。结合冻融循环试验和土壤物理组分区分阐明非生长季土壤有机碳的物理保护机制。