Myxomycetes in urban green space in subtropical China: Spatiotemporal patterns override forest type effects

Urban green areas are vital yet underexplored reservoirs of microbial diversity in cities. This study examines myxomycete communities in Zijin Mountain National Forest Park, a subtropical urban forest in Nanjing, China, across four seasons and multiple forest types. Combining field collections and moist chamber cultures, we documented 60 species from 906 occurrence records. Seasonal variation dominated community dynamics, with species richness peaking in summer and declining in winter. β-diversity was primarily driven by species turnover (β_sim = 0.23-0.28), with nestedness playing a minor role across temporal and spatial scales. Ceratiomyxa fruticulosa emerged as a forest-type indicator for mixed broad-leaved stands, while Arcyria cinerea and Cribraria violacea tracked seasonal humidity changes. Crucially, myxomycete composition showed no statistically significant differentiation among forest types, a departure from natural ecosystems, suggesting that urban management homogenizes habitats critical for microbial niche partitioning. These findings highlight urban parks' underrecognized role in preserving myxomycete diversity but reveal their vulnerability to microhabitat simplification. We advocate conseration of decaying wood and leaf litter to maintain ecological functions, offering actionable strategies for biodiversity-informed urban planning.