Ning Jiao, Liu Shengsheng, Kamran Muhammad, Sun Yi, Xu Lei, Wang Hua, Zhang Minglei, Chang Shenghua, West Charles P, Hou Fujiang
State Key Laboratory of Grassland Agro-Ecosystems, Ministry Lab, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, 730020, China.
Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409, USA.
Environ Res. 2022 Dec;215(Pt 1):114222. doi: 10.1016/j.envres.2022.114222. Epub 2022 Aug 30.
Alpine meadows, typical steppes, and deserts are among the globally important rangeland types that are generally distributed along temperature and precipitation gradients. Mineral losses caused by grazing are one of the key factors that can lead to instability or even degradation of these rangeland ecosystems.
We examined the concentrations of Cu, Fe, Mn, and Zn in soil, forage, and livestock dungs from diverse rangeland types in northwest China, to determine the relationships between these trace elements (TEs) concentrations and climatic factors (i.e., temperature, precipitation, and humidity), and to evaluate the potential risks of TEs deficiencies or excesses in these rangeland ecosystems.
Forage Zn concentrations in forage of all three types of rangeland, and Cu concentrations in forage of the alpine meadow did not meet the growth requirements of grazing livestock. Concentrations of Cu, Fe, and Mn in forage and Fe, Mn, and Zn in livestock dungs had quadratic parabola relationships with temperature, precipitation, and humidity, but the relationships between climate factors and Cu, Fe, and Mn concentrations in soil were not significant. In addition, the abilities of the plant to absorb Cu, Fe, and Zn from soil were stronger in the typical steppe than that in the alpine meadows and desert. Also, the abilities of livestock to return TEs to soil were stronger in the alpine meadow than that in the typical steppe and desert.
We derived a conceptual mode that the ratio of TE concentrations of the plant to soil and of livestock dung to forage represents the abilities of plants to absorb TEs from the soil matrix and livestock to return TEs to soil or to absorb TEs from forage, respectively. Results indicate potentially more serious risks of TEs deficiencies, especially that of Zn than previously considered in typical steppes and desert rangelands.
高山草甸、典型草原和沙漠是全球重要的牧场类型，通常沿温度和降水梯度分布。放牧造成的矿物质流失是导致这些牧场生态系统不稳定甚至退化的关键因素之一。
我们检测了中国西北不同牧场类型土壤、牧草和牲畜粪便中铜、铁、锰和锌的浓度，以确定这些微量元素（TEs）浓度与气候因素（即温度、降水和湿度）之间的关系，并评估这些牧场生态系统中TEs缺乏或过量的潜在风险。
三种牧场类型的牧草中锌浓度以及高山草甸牧草中的铜浓度均未达到放牧牲畜的生长需求。牧草中铜、铁和锰的浓度以及牲畜粪便中铁、锰和锌的浓度与温度、降水和湿度呈二次抛物线关系，但气候因素与土壤中铜、铁和锰浓度之间的关系不显著。此外，典型草原中植物从土壤中吸收铜、铁和锌的能力强于高山草甸和沙漠。而且，高山草甸中牲畜将TEs返还到土壤中的能力强于典型草原和沙漠。
我们得出一个概念模型，即植物与土壤以及牲畜粪便与牧草中TEs浓度的比值分别代表植物从土壤基质中吸收TEs以及牲畜将TEs返还到土壤或从牧草中吸收TEs的能力。结果表明，在典型草原和荒漠牧场中存在比之前认为的更严重的TEs缺乏风险，尤其是锌缺乏风险。
