太行山北部中山幼林地土壤水分的研究

STUDY ON THE DYNAMICS OF SOIL MOISTURE IN YOUNG PLANTATIONS ON THE MID-SLOPES OF NORTHERN TAIHANG MOUNTAINS

以太行山北部山西五台山中山地区幼林地土壤为研究对象，在阳坡、阴坡和半阳坡三种代表性立地上，从土壤水势、水容量等持水特性和土壤水分季节变化角度，并结合树木抗旱性和生长，研究了该地区土壤水分供应状况及其与造林成活和幼林生长的关系。研究表明，土壤有效水范围为－０．３－－２０ｂａｒ，正常生长水在－０．３－－３ｂａｒ，轻胁迫水－３－－１０ｂａｒ，中胁迫水为－１０－－２０ｂａｒ；土壤持水特性和有效水范围以阳坡最小，半阳坡最大；土壤自然含水率和有效水含量随降水而呈明显的季节变化特征，阴坡全年土壤含水率高，有效水充足，造林成活率高，幼林生长快，半阳坡和阳坡土壤含水率低，有效水较少，林木易于受旱，需选择抗旱树种，采取抗旱造林措施；整地可明显改善土壤水分状况，是抗旱造林和促进幼林生长的良好措施。

To find out the effect of the availability of soil moisture on the survival percentage and tree growth in young plantations,a study was carried out in three typical sites on the mid-slopes with different aspects,southerly, westerly and northwesterly, in northern Taihang Mountains.It was found that soil moisture available was ranged -0.3--20 bar,trees grew normally under the status of soil moisture ranged-0.3--3 bar.However,trees would be,slightly or moderately,suffering from water stress as the moisture available reduced to-3--10 bar and-10--20 bar. The results also indicated that the moisture capacity and range of moisture available is the least on the site southwards,on contrast,the largest westwards. The content and availability of soil moisture varied seasonally. Species choice should be considered to use those more resistant to drought for planting programmes, and the soil water conditions could be very much improved by site preparation.