苏北海堤主要防护林类型防蚀功能研究

A STUDY ON THE FUNCTION OF SOIL EROSION PROVENTION OF MAIN SHELTER FOREST TYPES ON SEAWALL IN NORTHERN JIANGSU PROVINCE

研究苏北海堤主要防护林防蚀能力得出：柳杉林土壤侵蚀量＜水杉林＜刺槐林＜无林区，年土壤侵蚀模数分别为９２２．２８８８ｔ／ｋｍ２·ａ、１２３１．２８２２ｔ／ｋｍ２·ａ和２６０８．４５３８ｔ／ｋｍ２·ａ。无林区发生土壤侵蚀的临界降雨量为５～８ｍｍ，有林地则为８～１０ｍｍ；对照区大于５０ｍｍ降水引起的土壤侵蚀量占全年土壤侵蚀量的８０．５％，有林地占９０％左右，表明雨量较大，尤其是大暴雨和特大暴雨往往引起较为严重的土壤侵蚀。雨量、最大某时段的降雨强度与土壤侵蚀量相关密切，平均雨强次之，与降水间隔期相关极差。另外，在主分量分析基础上确定了影响土壤侵蚀量的主要降水特征因子，结合各林分冠层截留量。

By located experiment on the function of main shelter-forest types on seawall and the analysis of influential factors in northern Jiangsu province, research results show the annual soil erosion modulus of these forest types in chinese cryptomeria(922、2888t/km 2·a)<water fir(1102、8044t/km 2·a)<black Locus(1231、2822t/km 2·a)<Wild Land(2608、4538t/km 2·a).Generally,when precipitation quantity is about 5-8mm,Soil erosion on wild Land will take place,but on forest Lands,the precipitation quantity is about 8-10mm.Quantity of soil erosion on wild land caused by rainfalls which are over 50mm per time is about 80 5% of total soil erosion amoumt per year.But on the forest land,the ratio is about 90%,the result shows that rainstorm,or greater rainstorm can cause greater soil erosin than that of normal precipitation.Among all precipitation characteristic factors,rainfall quantity,average intensity,especially,mean intensity of the period with maximum rainfall quantity have great influence on soil erosion,This paper also presents out the regression models showing relationship between soil erosion quantity and precipitation characteristic fctors.