Asymmetric effects of grazing intensity on macroelements and microelements in grassland soil and plants in Inner Mongolia

Grazing is a traditional grassland management technique and greatly alters ecosystem nutrient cycling. The effects of grazing intensity on the nutrient dynamics of soil and plants in grassland ecosystems remain uncertain, especially among microelements. A two-year field grazing experiment was conducted in a typical grassland with four grazing intensities (ungrazed control, light, moderate, and heavy grazing) in Inner Mongolia, China. Nutrient concentration was assessed in soil and three dominant plant species (Stipa krylovii, Leyums chinensis, and Cleistogenes squarrosa). Assessed quantities included four macroelements (carbon (C), nitrogen (N), phosphorus (P), and magnesium (Mg)) and four microelements (copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)). Soil total C, total N, total P, available N, and available P concentrations significantly increased with grazing intensity but soil Mg, Cu, Fe, Mn, Zn concentrations had no significant response. Plant C concentration decreased but ...

放牧是一种传统的草地管理手段，可显著改变生态系统的养分循环过程。当前，放牧强度对草地生态系统土壤与植物养分动态的影响仍存在不确定性，针对微量元素的相关效应尤其不明。本研究在中国内蒙古典型草原开展了为期两年的野外放牧试验，设置4种放牧强度梯度：无放牧对照组、轻度放牧、中度放牧与重度放牧。研究测定了土壤以及3种优势植物（克氏针茅（Stipa krylovii）、羊草（Leyums chinensis）、糙隐子草（Cleistogenes squarrosa））的养分含量，涉及的测定指标包括4种大量元素：碳（C）、氮（N）、磷（P）与镁（Mg），以及4种微量元素：铜（Cu）、铁（Fe）、锰（Mn）与锌（Zn）。土壤总碳、总氮、总磷、速效氮与速效磷含量随放牧强度升高显著上升，但土壤镁、铜、铁、锰、锌含量无显著响应；植物碳含量随放牧强度升高呈下降趋势，但……