毛乌素沙地南缘臭柏群落土壤肥力评价

以神木臭柏自然保护区臭柏(Sabina vulgaris Ant.)、草地等不同植物群落下的土壤为研究对象，选取9个典型样地采集土壤样本，在测定土壤理化性质、分析其空间分布特征的基础上，计算各项肥力指标的隶属度值，用修正内梅罗指数法对样地土壤肥力状况进行了评价。结果表明:（1）土壤养分在不同样地、不同土层之间差异显著（P < 0.05）；（2）各样地土壤物理性质均表现为无规律的变化；（3）各样地土壤养分垂直分布特征明显，表现出明显的表聚性，即养分含量随土层深度增加而降低；（4）不同植被、不同立地条件下的土壤肥力水平不同，不同坡位的土壤肥力为丘间低地（肥力指数0.376）> 沙丘下部（肥力指数0.356）> 沙丘中部（肥力指数0.341），不同坡向的土壤肥力为迎风坡（肥力指数0.435）> 背风坡（肥力指数0.417）；不同植被下的土壤肥力为草地（肥力指数0.417）> 臭柏（肥力指数0.376）> 沙地（肥力指数0.364）。研究表明研究区臭柏群落的土壤肥力总体处于中级水平。这一结果证明，植被恢复可以有效提高沙地土壤肥力水平。

Soil Fertility Evaluation in Sabina Vulgaris Ant. Community in the Southern Edge of the Mu Us Sandland

In order to study soil physical and chemical properties and soil fertility status under the Sabina vulgaris Ant. community on the southern edge of the Mu Us Sandland, we collected soil samples from 9 typical sampling plots with cutting ring, measured their physical and chemical properties, analyzed their spatial distribution characteristics, and evaluated soil fertility status of each plot by using the methods of membership value of fertility index and the modified Nemerow index. The results showed that: (1) The soil nutrients were significantly different (P < 0.05) among different plots and soil layers; (2) The soil physical properties of each plot in the study area showed an irregular fluctuation state. The soil nutrients in each plot had obvious vertical distribution characteristics. Especially, the soil chemical indices were obviously decreased with soil depths; (3) The soil fertility index was decreased in the order of lowland between hills (0.376) > lower dune (0.356) > middle dune (0.341), and was higher in the windward slope (0.435) than that in the Leeward (0.417). The soil fertility index outside the forest was the highest in the grassland (0.417), followed by Sabina vulgaris Ant. (0.376), and the lowest in the sand land (0.364). Soil fertility under the Sabina vulgaris Ant. community was at an intermediate level. Therefore, vegetation restoration in the study area can effectively improve sandy soil quality.