Functional Potential and Network-Based Insights into the Rhizosphere Microbiomes of Quercus mongolica and Larix kaempferi Stands

Evaluating forest functional indicators is essential for effective forest management planning. In this study, we conducted a metagenome-based comparative analysis of the rhizosphere soils from a natural Quercus mongolica stand and an artificial Larix kaempferi stand on Mt. Gariwang, Pyeongchang, Republic of Korea. Both stands originally belonged to the same natural forest and represent the current dominant tree species. Bacterial communities were affected more by climate than by tree species. A bacterial co-occurrence network analysis showed more complex interactions in the Q. mongolica than in L. kaempferi. Conversely, fungal communities were affected more by tree species than by climate. Specifically, the Q. mongolica stand had a high ratio of saprotrophic fungi, whereas the L. kaempferi stand exhibited a higher ratio of fungi associated with nutrient decomposition and harbored a high proportion of fungi that form ectomycorrhizae with long-distance exploration types. These fungal traits serve as indicators of soil ecological changes in Q. mongolica and L. kaempferi stands. Our comparative analysis of the microbial communities of Q. mongolica and L. kaempferi, representative plantation species in the Republic of Korea, revealed seasonal and host species–specific bacterial and fungal associations, and fungal communities were less variable than bacterial communities and more accurately reflected host tree traits.