Evidence for Reductions in Fungal Richness and Beta Diversity Dispersion Associated With Impervious Surfaces in California.

A large proportion of nutrient cycling and ecosystem services are supported by the activities of fungal communities. Though these communities have been comparatively understudied compared to more charismatic groups, there is a growing body of evidence that the structure of these communities is also impacted by urbanization. To investigate diversity patterns, we analyzed fungal occurrences recorded in California taken between 2015 and 2024. We investigated their differences in both richness and turnover by comparing communities sampled along a gradient of percent impervious coverage as a proxy for urbanization. We found evidence for a reduction in saprotrophic fungal richness for assemblages sampled from areas with higher levels of impervious coverage. We also found evidence that saprotrophic and symbiotrophic fungal assemblages tend to have reductions in beta diversity dispersion associated with a rise in impervious cover, potentially indicating an increase in biotic homogenization in more urbanized areas. In this study, we have demonstrated the potential use of processing large amounts of community science data to better understand the ecological responses of fungal communities against anthropogenic stresses.