Effects of "cave padded plastic film" afforestation technique in Loess hilly-gully regions

A new afforestation technique,“cave padded plastic film”,was proposed which was designed for forestation in Loess hilly-gully areas．The design of this technique is to dig a soil pit before planting,, padding plastic film （the thickness of the film is 0.0007 mm,, decomposable） around the wall and on the bottom of the soil cave；then planting, filling with soil and covered with film to avoid leakage and evaporation, making a closed and wet environment suitable for plant growth．From 1997 to 2001, the authors made many tests in Xiabian Valley,, Zaoyuan Town,, Baota District of Yan’an City, West China’s Shaanxi Province,to test the effects of this new technique,, compared with traditional ways．The results show that the “cave padded plastic film” afforestation technique can prevent evaporation of soil moisture and leakage of soil nutrition and remarkably improve the survival rate and growth of artificial afforestation,and this situation can last for more than 4 months．The survival rate can increase by 31.5％ and the biomass of branches by 57％．