Taxon-Specific Biodiversity Patterns and Cross-Taxon Associations Across Forest, Farmland, and Urban Green Spaces in Subtropical Eastern China

Biodiversity responses to habitat transformation may differ among taxonomic groups and vary seasonally, yet these dimensions are rarely evaluated simultaneously. We assessed vegetation, butterfly, frog, and bird diversity across forest, farmland, and urban green space in Dongyang, Zhejiang, China, using repeated seasonal surveys. Habitat, season, and their interaction were evaluated using models accounting for repeated observations within sampling plots. Cross-taxon associations were quantified using habitat-specific Spearman rank correlations based on richness, Shannon diversity, Pielou’s evenness, Gini–Simpson diversity, and abundance, with Benjamini–Hochberg correction for multiple comparisons. Species richness showed pronounced taxon-specific habitat associations: vegetation richness was highest in forests, butterflies and frogs were relatively well represented in farmlands, and birds showed the highest richness in urban green spaces. Richness generally increased toward summer and declined toward winter, while significant habitat × season interactions indicated that habitat differences varied temporally. Cross-taxon associations also differed markedly among habitats, demonstrating strong context dependence in the covariation among taxonomic groups. These findings indicate that biodiversity responses along the forest–farmland–urban gradient cannot be adequately represented by a single habitat ranking or a single taxonomic group. Multi-taxon and multi-season assessments, together with habitat-specific analyses, are therefore essential for disentangling biodiversity patterns and cross-taxon associations and for informing landscape-scale conservation in human-dominated landscapes.