Grazing effect on grasslands escalated by abnormal precipitations in Inner Mongolia

1. Grazing effects on arid and semi-arid grasslands can be constrained by aridity. Plant functional groups (PFGs) are the most basic component of community structure (CS) and biodiversity & ecosystem function (BEF). They have been suggested as identity-dependent in quantifying the responses to grazing intensity and drought severity. Here we examine how the relationships among PFGs, CS, BEF, and grazing intensity are driven by climatic drought. 2. We conducted a manipulative experiment with three grazing intensities in 2012 (non-drought year) and 2013 (drought year). We classified 62 herbaceous plants into four functional groups based on their life forms. We used the relative species abundance of PFGs to quantify the effects of grazing and drought, and to explore the mechanisms for the pathway correlations using structural equation models (SEM) among PFGs, CS, and BEF directly or indirectly. 3. Grazers consistently favored perennial forbs (e.g., palatable or nutritious plants), decre...1. 干旱半干旱草原的放牧效应可受干旱程度的调控。植物功能群（Plant Functional Groups, PFGs）是群落结构（Community Structure, CS）与生物多样性及生态系统功能（Biodiversity and Ecosystem Function, BEF）的最基本组成单元。已有研究表明，在量化放牧强度与干旱严重程度的响应时，植物功能群具有身份依赖性。本研究旨在探究气候干旱如何驱动植物功能群、群落结构、生物多样性及生态系统功能与放牧强度之间的关联。2. 本研究于2012年（非干旱年）与2013年（干旱年）开展了包含3个放牧强度梯度的控制性放牧实验。我们依据生活型将62种草本植物划分为4个功能群。通过植物功能群的物种相对多度，量化放牧与干旱的影响效应，并借助结构方程模型（Structural Equation Model, SEM）直接或间接探究植物功能群、群落结构与生物多样性及生态系统功能间路径关联的内在机制。3. 放牧动物始终偏好多年生杂类草（如适口性优良或营养丰富的植物），其……