沙化草地土壤有机碳及碳库管理指数的分异特征研究

本研究以宁夏盐池县潜在沙化草地(PD)、轻度沙化草地(LD)、中度沙化草地(MD)和重度沙化草地(SD)为对象，研究了不同沙化程度草地土壤有机碳(SOC)及其在不同粒径团聚体中的分布、活性有机碳组分和碳库指数在0～40 cm土层的变化，以探讨宁夏干旱风沙区沙化草地土壤有机碳及其碳库分配特征。结果表明：沙化导致草地SOC含量、储量及各粒级团聚体SOC含量显著降低，与PD相比，LD，MD和SD均降低40%以上。随草地沙化程度加剧，土壤易氧化有机碳(EOC)含量总体呈下降趋势，由PD的0.46～0.68 g·kg^-1降至SD的0.34～0.47 g·kg^-1，微生物量碳(MBC)含量在不同沙化程度草地之间差异不显著。伴随着草地沙化，EOC和MBC占SOC的比例逐渐升高，而碳库管理指数逐渐降低。由此，草地沙化可能会通过改变土壤有机碳活性而影响荒漠草原土壤碳库稳定性及草地生态环境质量。

Studies on Differentiation Characteristics of Soil Organic Carbon and Carbon Pool Management Index in Sandy Desertification Grassland

In this study,in order to explore the distribution characteristics of soil organic carbon (SOC) and carbon pool index in arid-sand grassland of Ningxia,we investigated the changes of SOC and its distribution in different particle size aggregates,active organic carbon component and carbon pool index in 0-40 cm soil layer of potential desertification grassland (PD),light desertification grassland (LD),moderate desertification grassland (MD) and severe desertification grassland (SD) in Yanchi County,Ningxia.. The results showed that the SOC content and SOC storage and the organic carbon contents of aggregates significantly decreased with desertification,and LD,MD and SD decreased by more than 40% when compared with PD. With the aggravation of grassland desertification,the content of soil easily oxidized organic carbon (EOC) decreased from 0.46~0.68 g·kg^-1 of PD to 0.34~0.47 g·kg^-1 of SD. There was no significant difference of microbial biomass carbon (MBC) contents among grasslands of different desertification degree. With the desertification of grassland,the proportion of EOC and MBC in SOC increased gradually,while the carbon pool management index decreased gradually. Therefore,grassland desertification may affect the stability of soil carbon pool and grassland ecological environment quality through changing the activity of soil organic carbon.