北川河流域退耕还林还草工程土壤渗吸性能研究

Soil Infiltration Capability of Project of Removal Lands From Cultivation for Afforestation and Grass planting in Beichuanhe Watershed

土壤渗吸性能是土壤重要的物理特征 ,是生态效益的重要组成部分。探讨退耕还林还草工程影响土壤渗吸性能的机制 ,可以为工程的顺利实施提供有关科学依据。应用双环渗透仪法 ,对国家退耕还林还草工程科技试验县———青海省大通县北川河流域退耕地土壤渗吸性能进行了系统研究。结果表明 :退耕地表土层渗吸过程基本上为INVERSE或S模型 ,突出表现为初期渗吸速度极大、中期降低、后期小 ,直至趋于某一常数亦即稳渗速度的过程。退耕地与天然林地的表土层 ,稳渗速度相同 ,平均达 4 2mm/min ,比农耕地高 9 5倍。随着退耕地林分的正常生长 ,林分枝叶重量的增加 ,枯落物的不断积累 ,表土层厚度的增加及改良 。

Infiltration is not only the important physical capability of soil but also the main part of the ecological benefits. The study on the mechanism of soil infiltration of the Project of Removal Lands from Cultivation for Afforestation and Grass planting (PRLCAG) could provide scientific bases for the project development favorably. Infiltration tests are carried out with the method of Double Test Rings in Beichuanhe Watershed of Datong County, Qinghai Province, one of the national experimental counties for PRLCAG. The results showed that the infiltration processes for epipedon of the rehabilitation lands have high rates at the beginning, medium rates at the mid periods, and lower rates at the ending time which are nearly unchangeable and trend to be constants, the whole process can be imitated well with Inverse and S models. With an average final infiltration rate of 4 2?mm/min, the epipedon of rehabilitation land has the same final infiltration function compared with natural forest land, and which is 9 5 times higher than that of cropland. The final infiltration capability can be gradually and effectively improved with the increase of branches and leaves growth of forest, accumulation of litter, thickening of epipedon and soil melioration along with the normal growth of the artificial forests in the rehabilitation lands.