Soil fungi link above and belowground carbon (C) fluxes through their interactions with plants and contribute to C and nutrient dynamics through the production, turnover, and activity of fungal hyphae. Despite their importance to ecosystem processes, estimates of hyphal production and turnover rates are relatively uncommon, especially in temperate hardwood forests. We sequentially harvested hyphal ingrowth bags to quantify the rates of Dikarya (Ascomycota and Basidiomycota) hyphal production and turnover in three hardwood forests in the Midwestern USA, where plots differed in their abundance of arbuscular- (AM) vs. ectomycorrhizal- (ECM) associated trees. Hyphal production rates increased linearly with the percentage of ECM trees and annual production rates were 66% higher in ECM- than AM-dominated plots. Hyphal turnover rates did not differ across the mycorrhizal gradient (plots varying in their abundance of AM vs. ECM trees), suggesting that the greater fungal biomass in ECM-dominated plots relates to greater fungal production rather than slower fungal turnover. Differences in hyphal production across the gradient aligned with distinctly different fungal communities and activities. As ECM trees increased in dominance, fungi inside ingrowth bags produced more extracellular enzymes involved in degrading nitrogen (N)-bearing relative to C-bearing compounds, suggesting greater fungal (and possibly plant) N demand in ECM-dominated soils. Collectively, our results demonstrate that shifts in temperate tree species composition that result in changes in the dominant type of mycorrhizal association may have strong impacts on Dikarya hyphal production, fungal community composition and extracellular enzyme activity, with important consequences for soil C and N cycling.

中文翻译：

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温带阔叶林中菌丝产量的变化而不是周转率调节了真菌生物量

土壤真菌通过与植物的相互作用将地上和地下的碳 (C) 通量联系起来，并通过真菌菌丝的产生、周转和活动促进碳和养分动态。尽管它们对生态系统过程很重要，但菌丝生产和周转率的估计相对不常见，尤其是在温带阔叶林中。我们依次收获了菌丝向内生​​长袋，以量化美国中西部三个硬木林中 Dikarya（子囊菌门和担子菌门）菌丝的产生率和周转率，这些地块的丛枝 - (AM) 与外生菌根 - (ECM) 相关的丰度不同树木。菌丝生产率随 ECM 树的百分比线性增加，ECM 的年生产率比 AM 主导的地块高 66%。菌根梯度上的菌丝周转率没有差异（AM 与 ECM 树丰度不同的地块），表明 ECM 主导地块中更大的真菌生物量与更高的真菌产量有关，而不是与更慢的真菌周转有关。梯度上菌丝产量的差异与明显不同的真菌群落和活动一致。随着 ECM 树的优势增加，向内生长袋内的真菌产生更多的细胞外酶，与含碳化合物相比，参与降解含氮 (N) 的化合物，表明在 ECM 主导的土壤中真菌（可能还有植物）对氮的需求更大。总的来说，我们的结果表明，导致主要菌根关联类型发生变化的温带树种组成的变化可能对 Dikarya 菌丝生产产生强烈影响，