Department of Biology and Geology, University of Almería, Almería, Spain.
Andalusian Centre for Assessment and Monitoring of Global Change (CAESCG), Almería, Spain.
Glob Chang Biol. 2022 Jan;28(1):115-127. doi: 10.1111/gcb.15931. Epub 2021 Oct 25.
Mounting evidence points to a linkage between biodiversity and ecosystem functioning (B-EF). Global drivers, such as warming and nutrient enrichment, can alter species richness and composition of aquatic fungal assemblages associated with leaf-litter decomposition, a key ecosystem process in headwater streams. However, effects of biodiversity changes on ecosystem functions might be countered by the presumed high functional redundancy of fungal species. Here, we examined how environmental variables and leaf-litter traits (based on leaf chemistry) affect taxonomic and functional α- and β-diversity of fungal decomposers. We analysed taxonomic diversity (DNA-fingerprinting profiles) and functional diversity (community-level physiological profiles) of fungal communities in four leaf-litter species from four subregions differing in stream-water characteristics and riparian vegetation. We hypothesized that increasing stream-water temperature and nutrients would alter taxonomic diversity more than functional diversity due to the functional redundancy among aquatic fungi. Contrary to our expectations, fungal taxonomic diversity varied little with stream-water characteristics across subregions, and instead taxon replacement occurred. Overall taxonomic β-diversity was fourfold higher than functional diversity, suggesting a high degree of functional redundancy among aquatic fungi. Elevated temperature appeared to boost assemblage uniqueness by increasing β-diversity while the increase in nutrient concentrations appeared to homogenize fungal assemblages. Functional richness showed a negative relationship with temperature. Nonetheless, a positive relationship between leaf-litter decomposition and functional richness suggests higher carbon use efficiency of fungal communities in cold waters.
越来越多的证据表明生物多样性与生态系统功能（B-EF）之间存在联系。全球驱动因素，如变暖与营养富集，会改变与叶凋落物分解相关的水生真菌组合的物种丰富度和组成，这是溪流源头的一个关键生态过程。然而，生物多样性变化对生态系统功能的影响可能会被真菌物种假定的高功能冗余所抵消。在这里，我们研究了环境变量和叶凋落物特征（基于叶化学）如何影响真菌分解者的分类和功能 α-和 β-多样性。我们分析了来自四个亚区的四种叶凋落物中真菌群落的分类多样性（DNA 指纹图谱）和功能多样性（群落水平生理特征），这些亚区在溪流水质和河岸植被方面存在差异。我们假设，由于水生真菌之间存在功能冗余，增加溪流水温和养分会比功能多样性更能改变分类多样性。与我们的预期相反，真菌分类多样性在整个亚区与溪流水质的变化关系不大，而是发生了分类替换。总体而言，分类 β-多样性比功能多样性高出四倍，这表明水生真菌之间具有高度的功能冗余。高温似乎通过增加β-多样性来提高组合的独特性，而营养浓度的增加则似乎使真菌组合同质化。功能丰富度与温度呈负相关。尽管如此，叶凋落物分解与功能丰富度之间的正相关关系表明，在寒冷水域真菌群落的碳利用效率更高。
