Roots promote the formation of slow‐cycling soil carbon (C), yet we have a limited understanding of the magnitude and controls on this flux. We hypothesised arbuscular mycorrhizal (AM)‐ and ectomycorrhizal (ECM)‐associated trees would exhibit differences in root‐derived C accumulation in the soil, and that much of this C would be transferred into mineral‐associated pools. We installed δ¹³C‐enriched ingrowth cores across mycorrhizal gradients in six Eastern U.S. forests (n = 54 plots). Overall, root‐derived C was 54% greater in AM versus ECM‐dominated plots. This resulted in nearly twice as much root‐derived C in putatively slow‐cycling mineral‐associated pools in AM compared to ECM plots. Given that our estimates of root‐derived inputs were often equal to or greater than leaf litter inputs, our results suggest that variation in root‐derived soil C accumulation due to tree mycorrhizal dominance may be a key control of soil C dynamics in forests.

中文翻译：

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根源输入是温带森林土壤碳的主要贡献者，但因菌根类型而异

根促进了土壤的缓慢循环（C）的形成，但是我们对这种通量的大小和控制的了解有限。我们假设与丛枝菌根（AM）和外生菌根（ECM）相关的树木在土壤中源自根的C积累上会表现出差异，并且其中大部分C会转移至与矿物相关的库中。我们安装δ ¹³跨菌根梯度C-丰富的内生内核在六个美国东部森林（ñ = 54个地块）。总体而言，与ECM为主的地块相比，AM的根源C高54％。与ECM样地相比，这导致AM中缓慢循环的矿物相关矿藏的根源碳含量几乎增加了两倍。鉴于我们对根源输入的估计通常等于或大于叶子凋落物的输入，我们的结果表明，由于树木菌根优势而导致的根源土壤碳积累的变化可能是森林中土壤碳动态变化的关键控制因素。