Biodiversity—both above- and belowground—influences multiple functions in terrestrial ecosystems. Yet, it is unclear whether differences in above- and belowground species composition (β-diversity) are associated with differences in multiple ecosystem functions (e.g., spatial turnover in ecosystem function). Here, we partitioned the contributions of above- and belowground β-diversity and abiotic factors (geographic distance, differences in environments) on the spatial turnover of multiple grassland ecosystem functions. We compiled a dataset of plant and soil microbial communities and six indicators of grassland ecosystem functions (i.e., plant aboveground live biomass, plant nitrogen [N], plant phosphorus [P], root biomass, soil total N, and soil extractable P) from 18 grassland sites on four continents contributing to the Nutrient Network experiment. We used Mantel tests and structural equation models to disentangle the relationship between above- and belowground β-diversity and spatial turnover in grassland ecosystem functions. We found that the effects of abiotic factors on the spatial turnover of ecosystem functions were largely indirect through their influences on above- and belowground β-diversity, and that spatial turnover of ecosystem function was more strongly associated with plant β-diversity than with soil microbial β-diversity. These results indicate that changes in above- and belowground species composition are one mechanism that interacts with environmental change to determine variability in multiple ecosystem functions across spatial scales. As grasslands face global threats from shrub encroachment, conversion to agriculture, or are lost to development, the functions and services they provide will more strongly converge with increased aboveground community homogenization than with soil microbial community homogenization.

中文翻译：

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与土壤微生物 β 多样性相比，多种生态系统功能的空间周转与植物更相关

生物多样性——包括地上和地下——影响陆地生态系统的多种功能。然而，尚不清楚地上和地下物种组成（β-多样性）的差异是否与多种生态系统功能的差异（例如，生态系统功能的空间周转）有关。在这里，我们划分了地上和地下 β 多样性和非生物因素（地理距离、环境差异）对多种草地生态系统功能空间周转的贡献。我们编制了植物和土壤微生物群落数据集和草地生态系统功能的六个指标（即植物地上活生物量、植物氮[N]、植物磷[P]、根生物量、土壤总氮、和土壤可提取 P）来自四大洲的 18 个草地，为营养网络实验做出了贡献。我们使用 Mantel 检验和结构方程模型来解开草地生态系统功能中地上和地下 β 多样性与空间周转之间的关系。我们发现非生物因素对生态系统功能空间周转的影响主要是通过它们对地上和地下 β 多样性的影响而间接产生的，并且生态系统功能的空间周转与植物 β 多样性的相关性比与土壤微生物的相关性更强。 β-多样性。这些结果表明，地上和地下物种组成的变化是一种与环境变化相互作用以确定空间尺度上多个生态系统功能可变性的机制。