荒漠草原沙漠化对土壤物理和化学特性的影响

以宁夏中北部荒漠草原不同沙漠化阶段(荒漠草地、固定沙地、半固定沙地、流动沙地)草地土壤为研究对象,研究不同沙漠化阶段土壤容重、孔隙度、土壤有机碳、全氮含量、碳密度、氮密度、NH4+-N和NO–3-N的变异规律,分析荒漠草原沙漠化对土壤物理和化学性质的影响。结果表明:固定沙地、半固定沙地和流动沙地0～30 cm土层土壤容重较荒漠草地分别升高了0.3%、2.9%和2.4%。土壤孔隙度随草地沙漠化加重整体表现为线性递减趋势。同一沙漠化阶段,随着土层深度的增加,土壤容重表现出先降低后升高趋势,而土壤孔隙度表现出相反的变化。随着荒漠草原沙漠化程度加剧,NH4+-N、NO–3-N、土壤有机碳、全氮含量和碳氮密度均呈线性下降趋势。与荒漠草地相比,流动沙地0～30 cm土层土壤NH4+-N、NO–3-N、土壤有机碳、全氮含量和碳氮密度分别降低了27.4%、31.8%、44.8%、56.7%、43.5%和55.7%。荒漠草原沙漠化破坏了土壤物理和化学性状。

Effects of Desertification on Soil Physiochemical Properties of Desert Grassland

The effects of different desertification stages (grasslands, fixed dunes, semi-fixed, mobile dunes) on soil bulk density, porosity, the contents and densities of organic carbon and total nitrogen, and the contents of ammonium nitrogen and nitrate nitrogen were studied in desert grassland located in north central Ningxia, China. The results showed that desertification of desert grassland had significant effects on soil physiochemical properties. As compared with grasslands, soil bulk densities of the fixed, semi-fixed and mobile dunes were increased by 0.3%, 2.9% and 2.4%, respectively. Soil porosity gradually decreased with increasing desertification stage. With the increase of soil depth, soil bulk density increased first, and then decreased under different desertification stages, but soil porosity first decreased and then increased. The contents of ammonium nitrogen, nitrate nitrogen, organic carbon and total nitrogen, and the densities of organic carbon and total nitrogen decreased gradually during the desertification process. As compared with grasslands, the contents of ammonium nitrogen and nitrate nitrogen, the contents and densities of organic carbon and total nitrogen in mobile dunes were increased by 27.4%, 31.8%, 44.8%, 56.7%, 43.5% and 55.7%, respectively. The above results suggested that desertification of desert grassland can deteriorate soil physiochemical properties.