Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Sci Total Environ. 2019 Dec 20;697:134189. doi: 10.1016/j.scitotenv.2019.134189. Epub 2019 Aug 29.
By altering plant and soil properties and microclimate environments, grazing has a profound influence on the structure and function of grassland ecosystems. However, few studies have addressed the potential grazing effects on snow accumulation and subsequent spring soil water after snow melting and soil thawing. In this study, vegetation properties, snow accumulation and soil water were measured in experimental plots subjected to 8 years of cattle grazing comprising six different grazing intensity treatments in a typical temperate grassland in eastern Eurasia. The results indicated that heavy grazing reduced the snow depth by 51% and the snow mass by 40%. Snow accumulation first rapidly increased but then remained relatively stable with increases in both the aboveground biomass and canopy height. An obvious inflection point occurred at approximately 200 g m aboveground biomass and at a 12.5 cm canopy height. The obvious difference in soil water content between the heavily grazed and ungrazed treatments occurred mainly in the spring after snow melting and soil thawing. The spring soil water content (0-30 cm) reached 31.5% in the ungrazed treatment (G0), which was 1.7 times that in the heavily grazed treatment (G0.92). The soil water content increased exponentially with increasing vegetation properties (aboveground biomass, canopy height and canopy cover), and a similar trend occurred with increasing snow mass and snow depth. Our structural equation modeling showed that both vegetation properties and snow accumulation had significant positive effects on spring soil water. By removing vegetation, grazing at increased intensities had significant, indirect suppressive effects on snow accumulation and spring soil water. Therefore, to obtain increased amounts of snow accumulation and spring soil water, land managers should consider reducing the grazing intensity or leaving some plots ungrazed.
放牧通过改变植物和土壤特性以及微气候环境，对草原生态系统的结构和功能产生深远影响。然而，很少有研究涉及潜在的放牧对积雪积累以及融雪和土壤解冻后春季土壤水分的影响。本研究在欧亚大陆东部典型温带草原中，设置了 8 年牛放牧的实验样地，包含 6 种不同的放牧强度处理，测量了植被特性、积雪积累和土壤水分。结果表明，重度放牧使积雪深度减少了 51%，积雪量减少了 40%。积雪积累首先迅速增加，但随着地上生物量和冠层高度的增加，随后相对稳定。在地上生物量约为 200 g m 和冠层高度为 12.5 cm 时，出现了明显的拐点。重度放牧和未放牧处理之间土壤水分含量的明显差异主要发生在融雪和土壤解冻后的春季。未放牧处理（G0）的春季土壤水分含量（0-30 cm）达到 31.5%，是重度放牧处理（G0.92）的 1.7 倍。土壤水分含量随植被特性（地上生物量、冠层高度和冠层盖度）的增加呈指数增长，与积雪量和积雪深度的增加呈相似趋势。我们的结构方程模型表明，植被特性和积雪积累对春季土壤水分有显著的正向影响。通过去除植被，增加放牧强度对积雪积累和春季土壤水分有显著的间接抑制作用。因此，为了获得更多的积雪积累和春季土壤水分，土地管理者应考虑降低放牧强度或保留一些未放牧的草地。
