Fungal Diversity and Its Relationship with Environmental Factors in Oaxaca and Surrounding States in Southern Mexico

Fungal communities exhibit strong spatial and environmental structuring across forest ecosystems, yet the drivers shaping their diversity patterns remain incompletely understood. In this study, we combined multivariate ordination, clustering analyses, and Zeta diversity (ζ-diversity) metrics to characterize fungal assemblages across environmental gradients. Canonical Correspondence Analysis (CCA) revealed that fungal community composition was significantly associated with climatic variables, particularly seasonal precipitation, thermal variation, and elevation. Hierarchical and K-means clustering identified coherent community clusters that differed in species richness and alpha diversity. Bray–Curtis distances and a Ward-based dendrogram further supported this separation, revealing a clear hierarchical structure in community similarity. Zeta diversity analysis indicated a slower species turnover, suggesting niche assimilation and habitat homogenization. Furthermore, the grouping of fungal assemblages followed a power-law model, emphasizing the role of deterministic environmental filtering. Critically, our findings reveal that only 1208 (33.5%) of the 3606 recorded species are present within existing Protected Natural Areas (PNAs), indicating a significant conservation gap. Together, these results provide an integrated ecological understanding of fungal diversity patterns, highlighting how climate–topography interactions structure communities and emphasizing the urgent need to align conservation strategies with these environmental drivers.