植被恢复对毛乌素沙地土壤pH和养分含量的影响

为明确陕北毛乌素沙地不同植被恢复后土壤pH和养分含量差异及其空间分布情况，本研究使用经典统计和地统计方法，定量研究了该研究区域内不同植被恢复后土壤的pH、有机碳（SOC）、全磷（TP）、全氮（TN）和铵态氮（AN）差异及其空间变异特征。结果表明，不同植被恢复后，除有机碳外，其它各个指标呈现出大致相似的变化规律，4种植被的恢复效果为农地 > 林地 > 草地 > 灌木；pH的变异系数是8.34%，属于弱变异，块金系数是9.98%，具有强空间相关性；SOC、TP、TN和AN变异系数分别是86.44%、31.92%、87.76%和58.58%，属于中等变异，块金系数分别是40.62%、49.82%、49.94%和40.55%，具有中等空间相关性；半方差函数最佳拟合模型除AN是球面模型外，其它指标都是指数模型；各种养分含量总体上均表现出从东北往西南方向递减的趋势。

Effects of Vegetation Restoration on Soil pH and Nutrient contents in the Mu Us Sandland

In order to clarify the differences of soil pH and nutrients and their spatial distribution under different vegetation types, we quantitatively analyzed the differences and spatial variation of pH, soil organic carbon (SOC), total phosphorus (TP), total nitrogen (TN) and ammonium nitrogen (AN) under different vegetation recovery types in the study area by combining the classical statistics and geostatistical methods. The results showed that all indicators (except for SOC) presented similar changes after different vegetation restorations. On the whole, the restoration effect decreased in the order of farmland > woodland > grassland > shrub. The variation coefficient of pH was 8.34%, which belonged to weak variation. And the nugget coefficient was 9.98%, which indicated a strong spatial correlation. The variation coefficients of SOC, TP, TN and AN were 86.44%, 31.92%, 87.76% and 58.58%, which belonged to moderate variation, respectively. And their nugget coefficients were 40.62%, 49.82%, 49.94% and 40.55%, showing medium spatial correlation, respectively. The best fitting model of AN was spherical model, and the best fitting model of the other indices was exponential model. In general, the distribution pattern of each index was gradually decreased from northeast to southwest of the study area.