Effects of grazing patterns on grassland biomass and soil environments in China: A meta-analysis

BackgroundGrazing has important influences on the structures and functions of grassland ecosystems, but the effects of grazing patterns on grassland biomass and soil environments in China remain unclear.ObjectiveWe employed a meta-analysis to identify the response of biomass and soil environments to different grazing patterns in China.MethodsPeer-reviewed journal articles were searched using the Web of Science and China National Knowledge to compile a database. A total of 1011 sets of sample observations satisfied the sampling standards; these were derived from 140 study sites and were obtained from 86 published articles. We conducted random effects meta-analyses and calculated correlation coefficients with corresponding 95% confidence intervals.ResultsGrazing significantly decreased the total biomass, aboveground biomass (AGB), belowground biomass (BGB), soil organic matter, soil total nitrogen, soil total phosphorus and soil water content but increased the root-to-shoot ratio, soil available nitrogen, soil pH and bulk density. Generally, increasing grazing intensity and duration significantly increased the effects of grazing on the biomass and soil environment. Additionally, the smallest effects of grazing on the biomass and soil environments were observed under light grazing and cattle grazing alone. Moreover, non-growing season grazing significantly increased AGB, while annual grazing and growing-season grazing significantly reduced AGB. Furthermore, AGB was positively correlated with soil organic matter, soil available phosphorus and bulk density, while BGB was negatively correlated with pH.ConclusionsThese findings highlight the importance of grazing patterns in the biomass and soil environment response to grazing and suggest that cattle grazing alone and grazing during the non-growing season are beneficial for improving the quality of grassland in China.

背景：放牧对草原生态系统的结构和功能具有重要影响，然而，在中国，放牧模式对草原生物量和土壤环境的影响尚不明确。目标：本研究采用元分析方法，旨在识别中国不同放牧模式对生物量和土壤环境的影响。方法：通过检索 Web of Science 和中国知网等数据库，筛选出经过同行评审的期刊文章，构建了相关数据库。共计1011组符合采样标准的样本观测数据，这些数据来源于140个研究站点，并来自86篇已发表的论文。我们进行了随机效应元分析，并计算了相应的相关系数及其95%置信区间。结果：放牧显著降低了总生物量、地上生物量（AGB）、地下生物量（BGB）、土壤有机质、土壤总氮、土壤总磷和土壤含水量，但提高了根冠比、土壤有效氮、土壤pH值和土壤容重。总体而言，增加放牧强度和持续时间显著增强了放牧对生物量和土壤环境的影响。此外，在轻度放牧和单独牛放牧的情况下，放牧对生物量和土壤环境的影响最小。此外，非生长季节放牧显著增加了AGB，而年度放牧和生长季节放牧则显著降低了AGB。进一步地，AGB与土壤有机质、土壤有效磷和土壤容重呈正相关，而BGB与pH值呈负相关。结论：这些发现突显了放牧模式对放牧对生物量和土壤环境响应的重要性，并表明单独牛放牧和非生长季节放牧有利于提升中国草原的品质。