Effects of mixed Hippophae rhamnoides on community and soil in planted forests in the Eastern Loess Plateau, China

Planted forests are very important in restoration of disturbed lands in the Loess Plateau, China. Pinus tabulaeformis and Platycladus orientalis are common tree species in plantation in Eastern Loess Plateau. Hippophae rhamnoides with its rich root nodules is a local and high-productivity shrub species. This study tried to test the roles of H. rhamnoides in enriching community structure, increasing species diversity and improving soil conditions in mixed coniferous plantations. Five forest types, P. tabulaeformis and H. rhamnoides mixed forest, P. orientalis and H. rhamnoides mixed forest, P. tabulaeformis pure forest, P. orientalis pure forest, and H. rhamnoides pure shrubland, were investigated and compared 21 years after plantation. The results showed that H. rhamnoides had significant positive effects on community structure, species diversity, soil physical and nutrient conditions etc. in mixed forests over pure forests. P. tabulaeformis forest and P. orientalis forest mixed with H. rhamnoides were suitable plantation models. P. tabulaeformis is more suitable in loess area than P. orientalis.