放牧到禁牧对草地土壤有机碳累积及其主控因子的影响

Change of soil organic carbon accumulation in grasslands and main control factors from grazing to prohibition of grazing

放牧是草地生态系统最为重要的人为影响因子,禁牧则是修复退化草原最有效的措施之一,不同管理模式势必会影响土壤理化指标和土壤有机碳(Soil Organic Carbon, SOC)及其累积量(SCS)的时空分布。为了明确从放牧到禁牧草地SCS变化过程及其影响因子,对锡林郭勒盟额里图牧场2019—2021年从放牧到禁牧SOC及土壤容重、水分、pH和生物量等进行分析。结果表明,禁牧区SCS逐年呈递增趋势,尤其是60cm土层SCS从2.54kg/m^(2)增加到4.61kg/m^(2),增加了81.5%。放牧区则呈递减趋势,从5.27kg/m^(2)下降到4.05g/m^(2),降低了23.15%。放牧既破坏了土壤结构又影响了草原植被,使草原生物量和土壤水分减少,土壤容重增加,同时Mantel-test分析和结构方程表明,土壤容重、全氮、温度、水分、地下生物量对SCS不同程度的影响比较明显,本研究可为草地生态研究及管理模式优化提供参考。

Grazing is the most importantly anthropogenic influence on grassland ecosystem.One of the most effective measures to rehabilitate the degraded grasslands is prohibition of grazing.However,different management patterns will inevitably affect the spatial and temporal distribution of soil physicochemical indicators and soil organic carbon(SOC)and its accumulation(SCS).In order to clarify the process of SCS change from grazing to prohibition of grazing and its influencing factors,this paper analysed the SOC and soil capacitance,moisture,pH and biomass from grazing to prohibition of grazing in Eritu pasture in Xilingole Meng from 2019-2021.The results indicated that the SCS in the prohibition of grazing area showed an increasing trend year by year,especially in the 60 cm soil layer where the SCS increased by 81.5%,i.e.from 2.54 kg/m^(2) to 4.61 kg/m^(2).The SCS in the grazing areas decreased by 23.15%,i.e.from 5.27 kg/m^(2) to 4.05 g/m^(2).Grazing destroyed soil structure and affected grassland vegetation,which reduced grassland biomass and soil moisture,as well as increased soil capacity.Mantel-test analysis and structural equations also showed that soil bulk,total N,temperature,moisture and belowground biomass had significant effect on the SCS.This study can be used as a reference for ecological research and management optimization of grasslands.