科尔沁沙地南缘不同植被对土壤物理性质改良作用研究

试验选取科尔沁沙地南缘樟子松林地、柠条林地、狗尾草草地、裸沙地（对照）4种典型立地类型为研究对象，通过测定各研究地土壤容重、土壤含水率、最大持水量、毛管持水量、田间持水量及沙粒粒径等物理指标，研究分析不同植被对沙地土壤物理性质的改良作用。研究表明:3种植被都对土壤物理性质都有一定改良作用。（1）柠条和樟子松对沙地土的保水效果较差，1 m深处的土壤含水率仅为2.1%和2.6%，低于裸沙地，而狗尾草草地1 m深处的含水率达到7.4%，为裸沙地1 m深处的1.6倍。（2）通过分析0—30 cm各物理指标平均值，得出3种植被下，土壤容重都小于裸沙地；狗尾草草地毛管持水量和田间持水量都最高，分别为21.7%和18.2%。其次为柠条林地和樟子松林地，裸沙地最小；柠条林地最大持水量最高，为24.6%，其次为狗尾草草地和樟子松林地，裸沙地最小。（3）通过对不同土层深度物理指标分析得出:3种植被对0—10 cm和10—20 cm的土壤容重、最大持水量、田间持水量有显著影响，而对毛管持水量没有显著影响；对20—30 cm的土壤各指标都有显著的影响。（4）三种植被对土壤颗粒分布异质性改良效果的大小顺序依次为狗尾草 > 樟子松 > 柠条，其间接反映了土壤粒径分布范围的均匀程度，其由高到低依次为狗尾草 > 樟子松 > 柠条。综上，与裸沙地相比，种植各植被土壤的物理指标明显好于裸沙地，表明植被能明显改善当地土壤的物理性质。

Research for Effect of Different Types of Vegetation on Physical Properties Improvement of Sandy Soil in the Sandy Land in South Horqin

The experiment selected four typical sites of sandy lands with Pinus sylvestris forest, Caragana intermedia forest, green bristlegrass and bare sandy land (control) in the south edge of Horqin as the research samples. Through the study of physical index determination of soil bulk density, soil moisture content, maximum water holding capacity, capillary water holding capacity, field moisture capacity and particle size analysis, the effect of different vegetation on soil physical properties were examined. The results show that three kinds of vegetation could completely improve the soil physical properties to some extent. (1) Caragana intermedia and Pinus sylvestris have poor water conservation capacity and soil moisture contents in 1 m depth was only 2.1% and 2.6%, respectively, which are lower than that of the bare sandy land. However the soil moisture content in the depth of 1 m of green bristlegrass reached to 7.4%, which is about 1.6 times more than that in the depth of 1 m in the bare sandy land. (2) By analyzing the average value of each physical index in 0—30 cm layer, we may draw the conclusion that the sandy sites with three kinds of vegetation have the lower soil bulk density than bare sandy land. The capillary water holding capacity and field moisture capacity of green bristlegrass are the highest, which are 21.7% and 18.2%, respectively. The next is Caragana intermedia forest and Pinus sylvestris forest and the smallest is bare sandy land. The maximum water holding capacity of Caragana intermedia forest is the highest one, which is 24.6%. The next is green bristlegrass and Pinus sylvestris, and the bare sandy land is the smallest one. (3) Through the analysis of the physical indexes of different soil depths, we may come to conclusion that at the depth of 0—10 cm and the depth of 10—20 cm, three kinds of vegetation have the significant impact on soil bulk density, maximum water holding capacity and field moisture capacity, but does not have the significant impact on the capillary water holding capacity. Three kinds of vegetation have the significant impact on each physical index at the depth of 20—30 cm. (4) The improvement effect caused by the three kinds of vegetation on the heterogeneity of soil distribution followed the order:green bristlegrass > Pinus sylvestris > Caragana intermedia, which indirectly indicated that the uniformity coefficient of particle size distribution in the sandy soil under different vegetation forms followed the order:green bristlegrass > Pinus sylvestris > Caragana intermedia. Compared with the bare sandy land, the soil physical indexes of various vegetation types are better than the bare sandy. The results show that vegetation can significantly improve the local soil physical properties.