Wu Yantao, Li Hao, Cui Jiahe, Han Ying, Li Hangyu, Miao Bailing, Tang Yongkang, Li Zhiyong, Zhang Jinghui, Wang Lixin, Liang Cunzhu
College of Life Sciences, Inner Mongolia University, Hohhot, China.
Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China.
Front Plant Sci. 2024 Feb 28;15:1294895. doi: 10.3389/fpls.2024.1294895. eCollection 2024.
Livestock presence impacts plant biodiversity (species richness) in grassland ecosystems, yet extent and direction of grazing impacts on biodiversity vary greatly across inter-annual periods. In this study, an 8-year (2014-2021) grazing gradient experiment with sheep was conducted in a semi-arid grassland to investigate the impact of grazing under different precipitation variability on biodiversity. The results suggest no direct impact of grazing on species richness in semi-arid grassland. However, increased grazing indirectly enhanced species richness by elevating community dominance (increasing the sheltering effect of grass). Importantly, intensified grazing also regulates excessive community biomass resulting from increased inter-annual wetness (SPEI), amplifying the positive influence of annual humidity index on species richness. Lastly, we emphasize that, in water-constrained grassland ecosystems, intra-annual precipitation variability (PCI) was the most crucial factor driving species richness. Therefore, the water-heat synchrony during the growing season may alleviate physiological constraints on plants, significantly enhancing species richness as a result of multifactorial interactions. Our study provides strong evidence for how to regulate grazing intensity to increase biodiversity under future variable climate patterns. We suggest adapting grazing intensity according to local climate variability to achieve grassland biodiversity conservation.
牲畜的存在会影响草原生态系统中的植物生物多样性（物种丰富度），然而，放牧对生物多样性的影响程度和方向在不同年份差异很大。在本研究中，在半干旱草原上进行了一项为期8年（2014 - 2021年）的绵羊放牧梯度实验，以研究不同降水变率条件下放牧对生物多样性的影响。结果表明，放牧对半干旱草原的物种丰富度没有直接影响。然而，放牧强度增加通过提高群落优势度（增加草丛的庇护作用）间接增加了物种丰富度。重要的是，高强度放牧还调节了因年际湿润度增加（标准化降水蒸散指数）导致的群落生物量过剩，放大了年湿度指数对物种丰富度的积极影响。最后，我们强调，在水分受限的草原生态系统中，年内降水变率（PCI）是驱动物种丰富度的最关键因素。因此，生长季的水热同步可能缓解植物的生理限制，通过多因素相互作用显著提高物种丰富度。我们的研究为在未来气候变化模式下如何调节放牧强度以增加生物多样性提供了有力证据。我们建议根据当地气候变率调整放牧强度，以实现草原生物多样性保护。
