土壤水分是植被成活的主要限制因子之一,探究拉萨半干旱河谷宜林地土壤水分影响因子,可为区域植被恢复提供理论依据。选取了河滩地、阶地和坡麓地3种地类7个典型宜林地立地类型,通过实地调查,选择土壤性状、地形地貌、植被类型三大类环境要素10个土壤水分影响因子,采用相关性和主成分分析方法探讨土壤水分的主导因素及其相互关系。研究结果表明:3种地类土壤水分环境影响因子关系存在一定差别,河滩地、阶地表现基本一致,土壤含水量与环境因子之间相关性不显著,环境因子之间相关显著;坡麓地土壤水分与环境因子显著相关,环境因子间相关性也明显。影响河滩地、阶地土壤水分的主要因子为土壤性状、其次为植被类型;影响坡麓地土壤水分因子地形地貌最强、植被类型次之、最后为土壤性状。土壤水分是多因素共同作用的结果,3种地类主成分明确,对土壤水分解释明显,地形、植被、土壤是影响拉萨半干旱河谷土壤水分的主要因子。

Soil moisture is one of the main limiting factors in vegetation survival.The objective of this study is to provide a theoretical basis for vegetation restoration in semi-arid valley area in Lhasa by studying environmental factors that affected soil moisture.In this study,three land types(flood land,terrace and footslope)including 7 typical forestland sites were selected.In field investigation,a survey of 10 environmental factors that were classified into soil properties,topography and geomorphology,and vegetation types,was conducted.The major factors affecting soil moisture and relationship among factors were analyzed with correlation analysis and principal component analysis.The results showed that the relationships between soil moisture and environmental factors were inconsistent among 3 different land types,whereas the same relationship was found between flood land and terrace.There was a non-significant positive or negative correlation between soil moisture and environmental factors.However,significant positive correlations were found among environmental factors.In footslope area,the soil moisture was significantly related to the environmental factors,and the correlation between environmental factors was significant as well.The key factor affecting the soil moisture in flood land and terrace was soil properties first,followed by vegetation types.The strongest factors affecting soil moisture in footslope area were topography and geomorphology,and the vegetation type was next.The soil properties had the weakest influence.Soil moisture was the result of the effects of a number of environmental factors.For each land type,the principal components were definite,which had a clearly explanation for soil moisture.The topography,vegetation and soil type were major factors that affected soil moisture in semi-arid valley of Lhasa.