Liu Minxia, Yin Fengling, Xiao Yindi, Yang Cunliang
College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China.
College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China.
Sci Total Environ. 2023 Nov 10;898:165445. doi: 10.1016/j.scitotenv.2023.165445. Epub 2023 Jul 12.
The relationship between biodiversity and ecosystem multifunctionality (EMF) depends on changes in environmental disturbance. Plant and soil biological diversity can mediate EMF, but how these change in response to grazing disturbance remains unknown. Here we present an 8-year experiment on sheep grazing control in alpine grasslands in Gannan Tibetan Autonomous Prefecture, Gansu Province, China. Plant species richness, FRic (functional richness), PD (Faith's phylogenetic diversity), soil biological diversity (bacterial, fungal, and ciliate diversity), and multiple ecosystem functions were measured and calculated. The results showed that increasing grazing intensity caused a decrease in biodiversity and EMF and that biodiversity and ecosystem function differed significantly (P < 0.05) between grazing intensities. EMF was positively correlated with species richness, functional diversity, and soil bacterial diversity (P < 0.05), with 23.6 %, 10.8 %, and 12.1 % of EMF explained by changes in grazing intensity, respectively. The interaction terms of grazing intensity, plant species richness, and soil biological diversity were negatively correlated with EMF (P < 0.05). This shift in the relationship between plant or soil biological diversity and EMF occurs at a grazing intensity index of around 0.7, i.e., the impact of plant species richness on EMF is more significant when the grazing intensity index is below 0.67. The effect of soil biological diversity on EMF is more substantial when the grazing intensity index is above 0.86. Conclusion: High grazing intensity directly affects soil bulk density and pH and indirectly affects EMF by regulating plant species richness and soil biological diversity changes. Loss of plant and soil biological diversity can have extreme consequences under low and high grazing intensity disturbance conditions. Therefore, we must develop biodiversity conservation strategies for external disturbances to mitigate the effects of land use practices such as grazing disturbances.
生物多样性与生态系统多功能性（EMF）之间的关系取决于环境干扰的变化。植物和土壤生物多样性可以调节生态系统多功能性，但它们如何响应放牧干扰而变化仍不清楚。在此，我们展示了一项在中国甘肃省甘南藏族自治州高寒草原进行的为期8年的绵羊放牧控制实验。我们测量并计算了植物物种丰富度、功能丰富度（FRic）、系统发育多样性（PD）、土壤生物多样性（细菌、真菌和纤毛虫多样性）以及多种生态系统功能。结果表明，放牧强度增加导致生物多样性和生态系统多功能性降低，且不同放牧强度下生物多样性和生态系统功能存在显著差异（P < 0.05）。生态系统多功能性与物种丰富度、功能多样性和土壤细菌多样性呈正相关（P < 0.05），放牧强度变化分别解释了生态系统多功能性变化的23.6%、10.8%和12.1%。放牧强度、植物物种丰富度和土壤生物多样性的交互项与生态系统多功能性呈负相关（P < 0.05）。植物或土壤生物多样性与生态系统多功能性之间关系的这种转变发生在放牧强度指数约为0.7时，即当放牧强度指数低于0.67时，植物物种丰富度对生态系统多功能性的影响更为显著。当放牧强度指数高于0.86时，土壤生物多样性对生态系统多功能性的影响更为显著。结论：高放牧强度直接影响土壤容重和pH值，并通过调节植物物种丰富度和土壤生物多样性变化间接影响生态系统多功能性。在低放牧强度和高放牧强度干扰条件下，植物和土壤生物多样性的丧失可能会产生极端后果。因此，我们必须制定针对外部干扰的生物多样性保护策略，以减轻放牧干扰等土地利用方式的影响。
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