Impact of long-term fencing measures on soil physicochemical and stoichiometry characteristics of desert steppe in alpine regions

The effects of different enclosure years on soil physicochemical properties provide scientific basis for soil fertility evaluation and ecological restoration. However, the details on the effects of longterm fencing measures on soil physicochemical properties in alpine regions are still lacking. The soil physicochemical properties, soil nutrient content, and stoichiometric characteristics of desert grassland were examined in the desert steppe of northern Tibetan Plateau, where grazing exclusion using fences has been implemented. This study included conducting experiments on different soil layers during different duration (10, 11, and 12 years) of grazing exclusion using fences; natural plots with no grazing exclusion were used as a control variable. Results showed that several soil physicochemical indexes, such as soil organic matter, soil water content, soil capillary porosity, soil non-capillary porosity, and soil capillary water capacity, in plots under the fencing measures were higher than those in the natural plots. The soil bulk density of the 12- and 11-year grazing exclusion plots was lower than that of the natural plots. The clay content of the 10- and 12-year grazing exclusion plots was higher than that of the natural plots, and the sand content was lower than that of the natural plots. The soil nutrient content was especially low with less than the average level of soil nutrient content in China. The stoichiometric C/N, C/P, N/P, and C/K ratios were 10.28-16.39, 2.74-16.69, 0.24-1.53, and 0.27-0.82, respectively. This result indicates that the degree of organic carbon mineralization was relatively high, and there existed a certain N limitation in the study area. The implementation of enclosure is conducive to the accumulation of C and N. The results provide support for elucidating the physicochemical characteristics, soil nutrients, and nutrient cycling of desert steppe in the northern Tibetan Plateau and for the study of the allotted time of fencing project in the alpine region.