State Key Laboratory of Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, Gansu 730000, China.
College of Animal Science, Guizhou University, Guiyang 550025, China.
Sci Total Environ. 2023 Aug 20;887:164155. doi: 10.1016/j.scitotenv.2023.164155. Epub 2023 May 13.
The relationships between biodiversity and ecosystem functions (BEF) are crucial for ecosystem management. However, little is known about how grazing affects BEF relationships in the context of ecological succession. Here, using a 5-year experiment in a semiarid grassland of the Loess Plateau, China, we mainly focused on how grazing affected the relationships between plant species diversity and aboveground biomass (AGB) and explored the underlying mechanisms behind the relationships. In addition, we compared the plant dynamics of community composition and structure under no-grazing and grazing treatments during succession. We found that the plant species diversity-AGB relationship shifted from a negative-linear pattern in no-grazing to a humped-back model in grazing during plant community succession, suggesting that grazing could regulate dominant species and alter the availability of light resources to suppress competitive exclusion during succession. In addition, changes in annual plants over time played crucial roles in the BEF relationships. The increase in annual Salsola collina in this study, which also alters multiple mechanisms of plant interaction, had a significant effect on the negative-linear relationship both with and without grazing. On average, compared to no-grazing treatment, grazing significantly decreased the plant community density (39.53 %), cover (16.97 %), height (7.85 %), and AGB (9.35 %), but increased plant diversity, including species richness and the Shannon-Wiener index, and especially dramatically enhanced the Shannon-Wiener index (ranging from 1.55 to 2.13). These results underline the close association between grazing and the dynamics of plant communities in semiarid grasslands during succession. In particular, our findings further reveal grazing-dependent relationships between diversity and AGB, which have significant implications for the management and biodiversity conservation measures of semiarid grassland ecosystems.
生物多样性与生态系统功能（BEF）之间的关系对生态系统管理至关重要。然而，人们对于放牧如何影响生态演替过程中的 BEF 关系知之甚少。在这里，我们利用中国黄土高原半干旱草地的一个为期 5 年的实验，主要关注放牧如何影响植物物种多样性与地上生物量（AGB）之间的关系，并探讨了这些关系背后的潜在机制。此外，我们比较了无放牧和放牧处理下群落组成和结构在演替过程中的植物动态。我们发现，在植物群落演替过程中，植物物种多样性与 AGB 的关系从无放牧时的负线性模式转变为放牧时的驼峰模型，表明放牧可以调节优势种，并改变光资源的可利用性，以抑制演替过程中的竞争排斥。此外，随着时间的推移，一年生植物的变化在 BEF 关系中起着至关重要的作用。本研究中一年生猪毛菜（Salsola collina）的增加，也改变了植物相互作用的多种机制，对有无放牧情况下的负线性关系都有显著影响。平均而言，与无放牧处理相比，放牧显著降低了植物群落密度（39.53%）、盖度（16.97%）、高度（7.85%）和 AGB（9.35%），但增加了植物多样性，包括物种丰富度和香农-威纳指数，特别是显著提高了香农-威纳指数（范围为 1.55 至 2.13）。这些结果强调了放牧与半干旱草地演替过程中植物群落动态之间的密切联系。特别是，我们的研究结果进一步揭示了放牧依赖于多样性与 AGB 之间的关系，这对半干旱草地生态系统的管理和生物多样性保护措施具有重要意义。
