The interactions of fungal guilds have recently been proposed as drivers of organic matter transformation in forest soils. We conducted a pot experiment with Norway spruce seedlings planted in spruce needle litter inoculated with several fungal strains belonging to different ecological guilds (saprotrophic, mycorrhizal, and root endophytic) to assess how the fungi and their interactions affect the transformation of humic substances (HS) and phosphorus (P) in the litter. Several methods for the characterization of P forms and HS were employed, including ³¹P NMR, UV–Vis and FTIR spectroscopy.

Our results show that fungal interactions influence not only the flow of P in decaying (plant) litter but also the transformation of the soil organic matter itself. Pots with saprotrophic Gymnopus androsaceus generally retained more P and prevented the accumulation of phosphonates caused by mycorrhizal Hyaloscypha finlandica, highlighting the strong competitive ability of the former species. The increased mineralization of P caused by G. androsaceus was not observed in the combined treatments, suggesting that other present fungi took up part of the inorganic P. The tested fungi did not affect the amount of HS produced but changed the characteristics of the HS. Mycorrhizal H. finlandica and root endophytic Phialocephala fortinii increased the relative proportion of carboxylic moieties in the HS regardless of the presence or absence of G. androsaceus, probably via the production and incorporation of melanins. The UV–Vis absorbance characteristics of the HS were significantly influenced by fungal interactions. Mycorrhizal H. finlandica and Hebeloma bryogenes retarded humification, as determined by the A4/6 ratio. We attribute the similar shift observed in Serpula himantoides to the partial oxidative degradation of HS.

Our study shows that fungal root endophytes can significantly contribute to litter transformation along with mycorrhizal and saprotrophic fungi. The extent and patterns of the transformation seem to be species-dependent in all studied fungal groups.

真菌协会的相互作用最近被提出作为森林土壤中有机物转化的驱动力。我们对盆栽的挪威云杉幼苗进行了盆栽试验，该云杉针叶中接种了几种属于不同生态协会（腐生，菌根和根内生）的真菌菌株，以评估真菌及其相互作用如何影响腐殖质（HS）的转化和垫料中的磷（P）。采用了几种表征P型和HS的方法，包括³¹ P NMR，UV-Vis和FTIR光谱。

我们的研究结果表明，真菌相互作用不仅影响腐烂（植物）凋落物中磷的流动，而且还影响土壤有机质本身的转化。腐生的裸露藻（Gymnopus androsaceus）花盆通常保留更多的P，并防止由菌根透明质酸（Hyaloscypha finlandica）引起的膦酸盐的积累，突出了前者的强大竞争能力。在联合处理中未观察到由G. androsaceus引起的P矿化增加，这表明其他现存的真菌吸收了无机P的一部分。测试的真菌不会影响HS的产生量，但会改变HS的特性。菌根H. finlandica和根内生不论是否存在雄蔷薇菌，福氏披头草都会增加HS中羧基部分的相对比例，这可能是由于黑色素的产生和掺入。HS的UV-Vis吸收特性受到真菌相互作用的显着影响。由A4 / 6比率确定，菌根的H.finlandica和Bryogenes延缓了腐殖质。我们将在Serpula hisantoides中观察到的类似变化归因于HS的部分氧化降解。

我们的研究表明，真菌根内生菌可以与菌根和腐生真菌一起显着促进凋落物的转化。在所有研究的真菌组中，转化的程度和模式似乎是物种依赖性的。