The mycorrhiza-mediated pathway for soil organic matter (SOM) formation and consequences for the SOM turnover under short rotation forestry

丛枝菌根真菌（AM）和外生菌根真菌（EM）通过不同的机制影响土壤有机质（SOM）的数量和质量。目前尚不清楚土地利用从耕地作物向短轮作林业转变后主要菌根类型的变化如何影响土壤有机质的数量、组成和周转。因此，我们将在田间和实验室实验中操纵占主导地位的菌根类型来验证以下假设：(1)SRF下预计从AM到EM的变化，由于菌丝体形成和SOM稳定疏水酶的产生而导致SOM储存；(2) SRF后作物对AM的反向变化刺激腐生菌分解之前储存的SOM，并利用glomalin的聚集效应形成新的SOM。因此，我们将抽取最近和以前的长期SRF及其相应的参考地点。我们将研究菌根定植，SOM的数量和分子组成，包括标记物（几丁质，疏水蛋白，球囊素）。在有和没有EM的情况下，SOM的微生物分解将在孵化实验中使用13C研究进行研究。这将证明菌根C对SOM形成的重要性和可持续性。

Arbuscular- (AM) and ectomycorrhizal (EM) fungi influence soil organic matter (SOM) quantity and quality using different mechanisms. So far little is known how changes in the dominating mycorrhiza type occurring after land use change from arable crops to short rotation forestry (SRF) affect the quantity, composition and turnover of SOM. Therefore, we will manipulate the dominating mycorrhiza type in field and lab experiments to test the following hypotheses: (1) A change from AM to EM, expected under SRF, results in SOM storage due to mycelium formation and SOM stabilising hydrophobin production; (2) A back-change to AM in crops after SRF stimulates saprotrophs to decompose the previously stored SOM and forms new SOM using aggregating effects of glomalin. Accordingly, we will sample recent and former long term SRF and their corresponding reference sites. We will investigate the mycorrhizal colonisation, the amount and molecular composition of SOM including markers (chitin, hydrophobin, glomalin). The microbial decomposition of SOM in the presence and absence of EM will be investigated using 13C studies in incubation experiments. This will prove the importance and sustainability of mycorrhizal C for SOM formation.