A new tree-planting technique to improve tree survival and growth on steep and arid land in the Loess Plateau of China

Establishing forest cover in arid or drought-stricken regions is a challenging task facing countries with a high degree of desertification or risk of desertification. China's Loess Plateau is one such area, an extremely dry climate, especially in spring, and that has a highly dissected topography. A new tree-planting technique to improve drought resistance, in which planting holes are lined with biodegradable plastic to reduce drainage and evaporation, was tested in an arid, erosion-prone, hilly area of the Loess Plateau between 1997 and 2006, during a period of lower-than-normal precipitation. In this paper, we report the survival and growth of 15 tree species grown with and without the new plastic lining. The new tree-planting technique promoted root growth in the topsoil by keeping the soil moisture than the surrounding soil evident during the first 4 months after planting. Tree survival rates, branch growth increment per year, tenth-year canopy area, and tenth-year canopy density in trees planted using the new method increased by an average of 41.4%, 29.0%, 16.9%, and 65.3%, respectively, compared with the values for the conventional planting technique. This suggests that the new planting technique is more suitable than the conventional method for the study area's soil environment and climate, and may prove suitable for similar areas elsewhere in the world where survival and growth rates are low. The results of our study thus represent a potentially valuable alternative for forest restoration and soil conservation in arid zones.