Understory specific species appearances indicate the soil improvement of low-function Platycladus orientalis forest in Beijing’s mountainous areas

How to assess the effect of ecosystem restoration is a trending topic with all the restoration projects and ecosystem function studies in recent years. Although many studies have used different indicators and methods to evaluate ecosystem restoration effects, it needs a lot of site works to acquire the data. Low-function Platycladus orientalis forest restoration program in Beijing mountainous area has been started since 2002, in this study, the understory species of 92 plots were investigated and recorded. We assumed that the effect of ecosystem restoration would improve site conditions, especially for the soil conditions which might lead to the appearance of new species. The relationship between understory species and eleven site condition factors was elucidated by means of canonical correspondence analysis (CCA), further, specific species were chosen to represent the improvement and possible growth areas of specific species was predicted by Maximum Entropy model. Results shown that Spiraea pubescens, Deutzia parviflora, Chrysanthemum chanetii, Themeda triandra, Oplismenus undulatifolius were the main understory species which were sensitive to environmental factors, and their distribution were related to soil factors closely. The species of Spiraea pubescens, Chrysanthemum chanetii, Oplismenus undulatifolius had strong indication to soil nutrient, the appearances would happen when the comprehensive index of soil nutrient was above 81,64 and 61 respectively. The appearance of Chrysanthemum chanetii and Oplismenus undulatifolius would indicate that the soil nutrient level was in or above the range of medium, and the appearance of Spiraea pubescens would mean that the soil nutrient level was in or above the range of high in low-function Platycladus orientalis forest of Beijing mountainous area. Our study indicates that the specific species could as an indicator to reflect or evaluate the ecosystem restoration effect.