Abstract: Soil is one of the basic functional components of the alpine shrub ecosystem. This study aimed to provide scientific guidance for the restoration of the degraded alpine shrub ecosystem. A typical area of the alpine shrub ecosystem on eastern Qilian Mountain with and without enclosures was selected as the sampling site. We selected three typical shrubs (Rhododendron capitatum, Salix oritrepha, Potentilla fruticosa) for detailed analyses of their soil properties. We measured 10 soil physico-chemical properties: total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK), soil organic carbon (SOC), soil moisture (SM), bulk density (BD), and soil porosity (SP). We analyzed the relationships among soil physico-chemical properties of different distributed community types using various field and experimental methods and statistical analyses including one-way ANOVA, the Tukey-Kramer HSD test, and principal component analysis (PCA) across inside and outside enclosures. We also compared soils from under shrubs and outside the shrub canopy in this ecosystem. It was found that SM, SOC, TP, TK, and AN differed significantly between samples collected under shrubs and outside the shrub canopy, and SM, BD, SOC, TP, AN, and AP differed significantly between inside and outside enclosures. The PCA indicated that AN and SP contributed more to vegetation distribution than did other environmental factors in the fenced plots, and were important predictors of the distribution of different shrubs and plants inside fenced areas on eastern Qilian Mountain. The PCA also indicated that AN and TK contributed more than did the other environmental factors in the grazed plots, and were important predictors of the distribution of different shrubs and plants in grazed grassland on eastern Qilian Mountain. R. capitatum patches always had better soil physical and chemical properties, indicating that this plant has a strong anti-interference ability. The results of these analyses show that short-term enclosure can significantly increase the SM content and available nutrient content in soil in shrub patches, further confirming that fencing is the best way to restore degraded alpine shrub ecosystem.

Key words: Eastern Qilian Mountain, different types of shrub patches, soil physic-chemical properties, correlation analysis, principal component analysis