Aims

Understanding the linkage between community heterogeneity (β diversity) and ecosystem functioning is crucial for uncovering complex ecological processes that impact ecosystem stability and productivity. However, our understanding of how β diversity is associated with ecosystem functioning across environmental gradients remains limited.

Methods

We conducted an aridity-gradient transect survey of grassland over 3500 km across the Tibetan Plateau (a total of 80 grassland sites) to investigate the changes of plant and soil microbial diversities along a natural aridity gradient, and to evaluate the above- and belowground biomass and plant nutrient levels connected with the observed variation.

Results

Our results showed that plant richness, above- and belowground biomass, plant nutrient concentrations, and soil microbial α and β diversities (including taxonomic and functional) significantly decreased along the aridity gradient. Compared to the α diversities of plant and microbial community, their β diversities were more significantly correlated with above- and belowground biomass and plant carbon, nitrogen and phosphorus concentrations. Metagenomic functional profiles showed that β diversity of microbial functions, including genes of the carbohydrate metabolism responsible for carbon degradation, nitrification, energy production and conversion, material transport and coenzyme metabolism, had closer associations with plant biomass and nutrient concentrations than did their α diversities. These positive β biodiversity-functions association was weakened by the increasing aridity, mainly because the increasing aridity-induced lower biomass of plant functional groups (e.g., sedge and forbs), soil moisture and organic carbon content decreased both plant and soil microbial β diversities.

Conclusions

These findings provide novel insight into the biodiversity-ecosystem functions relationship and stress the crucial roles of above- and belowground β diversity in supporting alpine grassland biomass and nutrient levels. Biodiversity conservation to prevent large-scale community homogenization should be attached in alpine ecosystem.

中文翻译：

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植物和微生物β多样性比它们的α多样性更能预测生态系统功能，但干旱削弱了这些关联

 目标

了解群落异质性（β多样性）和生态系统功能之间的联系对于揭示影响生态系统稳定性和生产力的复杂生态过程至关重要。然而，我们对β多样性如何与跨环境梯度的生态系统功能相关联的理解仍然有限。

 方法

我们对青藏高原 3500 多公里的草地（共 80 个草原点）进行了干旱梯度样带调查，以调查植物和土壤微生物多样性沿自然干旱梯度的变化，并评估与观察到的变化相关的地上和地下生物量和植物养分水平。

 结果

我们的结果表明，植物丰富度、地上和地下生物量、植物养分浓度以及土壤微生物α和β多样性（包括分类和功能）沿干旱梯度显著降低。与植物和微生物群落的α多样性相比，它们的β多样性与地上和地下生物量以及植物碳、氮和磷浓度的相关性更显著。宏基因组功能特征显示，微生物功能β多样性，包括负责碳降解、硝化、能量产生和转化、物质运输和辅酶代谢的碳水化合物代谢基因，与植物生物量和养分浓度的关联比它们的α多样性更密切。干旱度的增加削弱了这些β生物多样性功能的正关联，主要是因为日益干旱导致植物功能群（如莎草和杂草）的生物量降低、土壤水分和有机碳含量降低了植物和土壤微生物β多样性。

 结论

这些发现为生物多样性-生态系统功能的关系提供了新的见解，并强调了地上和地下β多样性在支持高山草原生物量和养分水平方面的关键作用。高寒生态系统应加强生物多样性保护，防止大规模群落同质化。