Urbanization changes the richness and homogenizes fungal and invertebrate communities in California

A large proportion of nutrient cycling and ecosystem services are supported by the activities of fungal and invertebrate communities. Though these communities have been comparatively understudied compared to more charismatic groups such as birds and mammals, there is a growing body of evidence that the structure of these communities is also impacted by urbanization. Here we analyzed species occurrences derived from environmental DNA (eDNA), taken from over 20,000 samples in California, to investigate patterns of diversity for a variety of fungal and invertebrate orders. We investigated their differences in both taxonomic richness and turnover by comparing communities sampled in urban and non-urban areas. We found taxonomic richness was significantly lower within fungal orders sampled in urban areas, and most invertebrate orders displayed a similar pattern. Both invertebrate and fungal communities were found to have undergone a significant level of biotic homogenization in urban areas. We demonstrated that the composition of fungal and invertebrate communities, classified using eDNA, is significantly affected by the process of urbanization.