Kang Saruul, Wang Zhongwu, Guo Xulin, Zhao Mengli, Wu Saqila, Zhang Xia, Zhu Lin, Han Guodong
College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, 29 Ordos Rd., Hohhot, 010011, China.
Key Laboratory of Grassland Resources, Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Key Laboratory of Grassland Management and Utilization, Inner Mongolia Agricultural University, Hohhot, 010011, China.
Oecologia. 2025 Jan 8;207(1):18. doi: 10.1007/s00442-024-05647-3.
Although numerous studies have shown that grazing gives rise to community succession from the communities or even species perspective, there is a lack of discussion about how grazing drives community assembly based on plant functional traits in a long-term experiment. We find different grazing intensities lead to temporal effects on trait-mediated multidimensional community assembly processes, including community-weighted trait mean (CWM), trait filtering, and trait distribution (divergence/convergence). CWM, trait filtering, and trait distribution of different traits transformed over the 16-year grazing experiment. Major findings include the following: (1) CWM changed rapidly under higher grazing intensity, and the removal of unsuitable traits from communities over time was accelerated with higher grazing intensity, such as higher specific leaf area (SLA), rich epidermal appendages (PAP), deep root system (RD), and growth form (shrub and subshrub) and dispersal mode (DM, e.g., insect spread) with higher scores. (2) Patterns of trait filtering strongly depended on grazing intensity and trait types, most traits, such as SLA, DM, PAP, RD, and onset of flowering (OFL), were filtered at high grazing intensity area, and effects of trait filtering in the community assembly process strengthened with grazing time. (3) Traits related to the cycling of biological matter, such as leaf area (LA), SLA, reproductive height (RH), photosynthetic (PHO), and GF more frequently diverged after long-term grazing, especially in higher grazing areas. Community assembly in intensely grazed ecosystems takes over a decade to support fundamental functions, highlighting the need for grazing intensity thresholds for sustainable grassland use.
尽管众多研究表明，从群落甚至物种角度来看，放牧会引发群落演替，但在一项长期实验中，对于放牧如何基于植物功能性状驱动群落构建却缺乏相关讨论。我们发现不同的放牧强度会对性状介导的多维群落构建过程产生时间效应，包括群落加权性状均值（CWM）、性状过滤和性状分布（发散/收敛）。在长达16年的放牧实验中，不同性状的CWM、性状过滤和性状分布都发生了变化。主要研究结果如下：（1）在较高放牧强度下，CWM变化迅速，随着放牧强度的增加，群落中不合适性状随时间的去除速度加快，例如较高的比叶面积（SLA）、丰富的表皮附属物（PAP）、深根系（RD）以及具有较高得分的生长型（灌木和亚灌木）和扩散模式（DM，如昆虫传播）。（2）性状过滤模式强烈依赖于放牧强度和性状类型，大多数性状，如SLA、DM、PAP 、RD和开花起始时间（OFL），在高放牧强度区域被过滤，并且在群落构建过程中，性状过滤的效应随着放牧时间而增强。（3）与生物物质循环相关的性状，如叶面积（LA）、SLA、生殖高度（RH）、光合（PHO）和生长型（GF），在长期放牧后更频繁地发散，尤其是在高放牧区域。在重度放牧的生态系统中，群落构建需要十多年时间来支持基本功能，这突出了为实现可持续草地利用设定放牧强度阈值的必要性。
