How mycorrhizal types and tree diversity drive soil carbon stabilization.

土壤有机质（SOM）中储存了大量的碳（C），通过聚集体中的封闭或矿物表面的吸附来防止微生物分解。源有助于SOM变化很大，这取决于所考虑的SOM分数。颗粒有机质（POM）组分主要由结构组分和植物残体组成，矿物伴生有机质（MAOM）组分主要来自微生物残体。在温带森林中，树木和真菌之间的共生关系，即菌根，对土壤碳储量起着重要作用。与丛枝菌根（AM）的森林相比，以外生菌根（ECM）为主的森林具有更高的碳储量。然而，这些C股票不太稳定，POM MAOM的比例是在ECM森林高于AM森林。到目前为止，一个机械的理解，不同类型的菌根影响POM和MAOM组分中的C股票的因素和过程仍然缺乏。我们推测，菌根类型的影响代谢物的多样性和根沉积的动态，从而在土壤C稳定起着至关重要的作用。我们建议，在AM占主导地位的森林一个小的，但持续输入的高度多样化的根沉积物促进微生物群落，随后有助于增加C稳定的形式MAOM。与此相反，一个罕见的和高的C输入，以及腐食性真菌的抑制（Gadgil效应），促进POM积累ECM森林。为了测试这个合作项目的假设，我们将结合联合收割机一个既定的树多样性实验，操作菌根类型的丰度与创新的分区盆栽实验和国家的最先进的方法，如稳定同位素标记，生物标志物鉴定，液相色谱质谱/质谱。拟议的项目将有助于全面了解菌根类型驱动的机制，在温带森林中的碳周转。这为更好地预测森林生态系统碳储量的未来变化和制定新的森林管理策略以维持甚至增加土壤碳储量提供了可能性。

Soils store large amounts of carbon (C) in soil organic matter (SOM), which is protected from microbial decomposition by occlusion in aggregates or by sorption to mineral surfaces. Sources contributing to SOM vary widely depending on the SOM fraction considered. While the particulate organic matter (POM) fraction mainly consists of structural components and plant residues, the mineral-associated organic matter (MAOM) fraction is mainly derived from microbial residues. In temperate forests, the symbiosis between trees and fungi, the mycorrhiza, plays an important role for soil C storage. Forests dominated by trees with ectomycorrhiza (ECM) have higher C stocks compared to forests with arbuscular mycorrhiza (AM). However, these C stocks are less stabilized and the ratio of POM to MAOM is higher in ECM forests than in AM forests. To date, a mechanistic understanding of the factors and processes by which different types of mycorrhiza influence C stocks in POM and MAOM fractions is still lacking. We hypothesize that the mycorrhizal type influences the metabolite diversity and the dynamics of rhizodeposition and consequently plays a critical role in soil C stabilization. We propose that in AM-dominated forests a small but continuous input of highly diverse rhizodeposits promotes microbial communities, which subsequently contribute to increased C stabilization in the form of MAOM. In contrast, an infrequent and high C input, together with a suppression of saprotrophic fungi (Gadgil effect), promotes POM accumulation in ECM forests. To test the hypotheses of this collaborative project, we will combine an established tree diversity experiment that manipulates mycorrhizal type abundances with an innovative compartmented pot experiment and state-of-the-art methods like stable isotope labeling, biomarker identification, and liquid chromatography mass spectrometry/mass spectrometry. The proposed project will contribute to a comprehensive understanding of mycorrhizal type-driven mechanisms of C turnover in temperate forests. This opens the possibility to better predict future changes in C stocks in forest ecosystems and to develop new forest management strategies to maintain or even increase soil C storage.