Abstract. Soil functioning is intrinsically related to the structure of associated biological communities. This link is barely understood in the multispecies context of soil microbial communities, which often requires complex analytical approaches to discern structural and functional roles of microbial taxa inhabiting the soil. To investigate these ecological properties, we characterized the assembly and soil functioning contribution of ectomycorrhizal (ECM) fungal communities through co-occurrence network analysis. Co-occurrence networks were inferred from ECM root tips of Cistus albidus, Quercus faginea and Q. ilex on a regional scale, in Mediterranean mixed forests. Soil enzymatic activities related to carbon and nutrient cycling were also measured, and soil functionality outcomes related to ECM fungal network structure were evaluated on the community to taxon levels. Network complexity relied on habitat characteristics and seasonality, and it was linked to different dominant ECM fungal lineages across habitats. Soil enzymatic activities were habitat-dependent, driven by host plant identity and fungi with reduced structuring roles in the co-occurrence network (mainly within Thelephorales, Sebacinales and Pezizales). ECM fungal co-occurrence network structure and functioning were highly context-dependent, pointing to divergent regional fungal species pools according to their niche preferences. As increased network complexity was not related to greater soil functionality, functional redundancy might be operating in Mediterranean forest soils. The revealed differentiation between structural and functional roles of ECM fungi adds new insights into the understanding of soil fungal community assembly and its functionality in ecosystems.

中文翻译：

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外生菌根真菌网络复杂性决定土壤多酶活性


摘要。土壤功能本质上与相关生物群落的结构相关。在土壤微生物群落的多物种背景下，这种联系几乎不被理解，这通常需要复杂的分析方法来辨别土壤中微生物类群的结构和功能作用。为了研究这些生态特性，我们通过共现网络分析描述了外生菌根（ECM）真菌群落的组装和土壤功能贡献。共现网络是根据地中海混交林区域范围内的岩蔷薇、栎树和冬青树的 ECM 根尖推断的。还测量了与碳和养分循环相关的土壤酶活性，并在群落到分类单元水平上评估了与 ECM 真菌网络结构相关的土壤功能结果。网络复杂性取决于栖息地特征和季节性，并且与栖息地不同的主要 ECM 真菌谱系相关。土壤酶活性依赖于栖息地，由寄主植物特性和共现网络中结构作用减弱的真菌（主要在 Thelephorales、Sebacinales 和 Pezizales 内）驱动。 ECM真菌共现网络结构和功能高度依赖于环境，根据其生态位偏好指出不同的区域真菌物种库。由于网络复杂性的增加与土壤功能的增强无关，因此地中海森林土壤中可能存在功能冗余。 ECM 真菌的结构和功能作用之间所揭示的差异为理解土壤真菌群落组装及其在生态系统中的功能提供了新的见解。