Fungal Community Assembly in Standing Deadwood: Stochastic vs. Deterministic Processes Across Decay Stages*

A growing body of evidence suggests that fungi play an essential role in the decomposition process of deadwood. However, the dynamic pattern of fungal community assembly in deadwood remains poorly understood. Here, we employed a 'space-for-time' substitution approach in the local forest to track shifts in the deadwood mycobiota during decay. The results indicated that fungal community diversity increased from decay classes I to III, then decreased from decay classes III to IV. A high degree of structural similarity in fungal communities could occur between decay classes I and II, or decay classes III and IV. Fungal community assembly in decay classes III and IV was more governed by stochastic processes than in decay classes I and II. Moreover, we identified the six most important biomarkers and established a model that associates these biomarkers with decay classes using a random forest analysis. The chemical properties of deadwood substrates were determined to be the important driver of fungal community assembly and diversity. Our work provides novel insights into changes and the generation of fungal communities within deadwood.