Sustaining Ecological Functional Zones: The Stabilizing Role of Common Fungi Against Warming Revealed by Altitudinal Transect

Fungal communities, typically K-strategy, demonstrate significant potential to counteract environmental stresses. Theories of complexity- and biodiversity-stability suggest that ecosystem stability may be differentially influenced by common species, which engage in intense interactions, and rare species, which contribute to diversity. Here, taking advantage of −0.6 °C/100 m lapse rate, an altitudinal gradient in the Yan-Taihang Mountain Ecological Conservation Area was established, aiming to investigate the responses of common and rare fungi to climatic, plant, and edaphic variations and their potential roles in maintaining stability among low, mid, and high altitudes. Results showed that community composition, rather than diversity, was significantly influenced by altitude, with the abundance of symbiotrophs peaking at mid-altitudes and Saprotrophs at high altitudes. Rare fungi were less accounted for by environmental variables in terms of community composition, whereas their diversity was more sensitive to pH, total phosphorus, and electrical conductivity than the common fungi, indicating that rare species may serve as a resilient gene reservoir under environmental perturbations. The stability of fungal community was further enhanced through interactions among common fungi, with these interactions being slightly compartmentalized and tending more negative at mid (modularity = 0.73, negative-to-positive associations = 0.69%) and high altitudes (modularity = 0.77, negative-to-positive associations = 0.61%) compared with low altitudes (modularity = 0.67, negative-to-positive associations = 0.13%). These results highlighted distinct assembly strategies between common and rare fungi and underscored the importance of common fungi for the persistence of ecological functional zones amidst climate change.