宁南黄土区典型林地土壤抗冲性及相关物理性质

Soil Anti-scourability and Its Related Physical Properties on Typical Forestlands in Loess Hilly Region of Southern Ningxia

研究宁南黄土区典型林分类型土壤水文物理性质及抗冲性能,旨在从土壤抗冲性角度为该区域退耕还林工程的生态功能评价和树种配置提供科学依据。采用野外取样与室内试验相结合的方法,得到了4种林型(山杏纯林、山桃纯林、山杏×沙棘混交林、山杏×柠条混交林)的水文物理指标和土壤抗冲系数。结果表明:4种不同林型的土壤容重、总孔隙度、持水性能与抗冲系数存在显著差异。在0—30 cm土层,土壤容重随着土层深度的增加总体呈现递增的趋势,大小排序为山杏林×沙棘林>山杏林>山桃林>山杏×柠条林;土壤总孔隙度和毛管孔隙度随土层的加深而减小,其中山杏×柠条混交林的含量最高;最大持水量为山杏×沙棘林>山杏林>山桃林>山杏×柠条林,毛管持水量和田间持水量大小均为山杏×柠条林>山杏林>山桃林>山杏×沙棘林;4种林型的土壤抗冲系数为山杏×柠条林>山杏×沙棘林>山杏林>山桃林。土壤容重与土壤总孔隙度、毛管持水量、田间持水量、抗冲系数均呈现极显著的负相关,土壤总孔隙度与土壤田间持水量、抗冲系数呈现极显著的正相关关系。其中以土壤总孔隙度与土壤田间持水量、抗冲系数的相关性最好。通过上述分析,总体表现出山杏×柠条混交林优于其他3种林型,能够有效改善土壤结构,提高土壤抗侵蚀性能。

In this study,we analyzed the soil hydro-physical properties and soil anti-scourability in typical forest types in the loess hilly region of Southern Ningxia in order to provide scientific basis for the ecological function evaluation and tree species allocation of the project of returning farmland to forest in the region from the perspective of soil anti-scourability.Soil hydro-physical indices and scourability coefficient of 4 forest types(pure forest of Prunus sibirica,pure forest of Prunus davidiana,mixed forest of Prunus sibirica×sea-buckthorn,mixed forest of Prunus sibirica×Caragana korshinskii)were obtained by the method of field sampling and laboratory test.The results showed that there were significant differences in soil bulk density,total porosity,water retention capacity and anti-scourability coefficient of 4 different forest types.In 0—30 cm soil layer,the soil bulk density showed an increasing trend with the increase of soil depth,and soil bulk density decreased in the order:Prunus sibirica×Hippophae rhamnoides forest>Prunus sibirica forest>Prunus davidiana forest>Prunus sibirica×Caragana korshinskii forest.The total porosity and capillary porosity of soil decreased with the depth of soil layer.The maximum water holding capacity decreased in the order:Prunus sibirica×Hippophae rhamnoides forest>Prunus sibirica forest>Prunus davidiana forest>Prunus sibirica×Caragana korshinskii forest.Both the gross water holding capacity and field water holding capacity decreased in the order:Prunus sibirica×Caragana korshinskii forest>Prunus davidiana forest>Prunus sibirica×Hippophae rhamnoides forest.The soil anti-scourability coefficients of 4 forest types decreased in the order:Prunus sibirica×Caragana korshinskii forest>mountain apricot×Hippophae rhamnoides forest>Prunus sibirica forest>Prunus davidiana forest.Soil bulk density was negatively correlated with soil total porosity,capillary water holding capacity,field water holding capacity and soil anti-scourability coefficient,while soil total porosity was positively correlated with soil water holding capacity and impact resistance coefficient.The correlation between soil total porosity and soil water holding capacity and soil resistance coefficient was the best.Based on the above analysis,it is concluded that Prunus sibirica×Caragana korshinskii mixed forest is superior to the other three forest types,which can effectively improve the soil structure and the soil erosion resistance ability.