Seasonal Variation in Floral Resources and Their Associations with Flower-Visiting Bees and Butterflies in Five Urban Parks in Guangzhou, China

Urban parks provide floral resources for flower-visiting insects, but the availability of these resources and the flower visits they receive vary across seasons. We repeatedly surveyed 60 shrub and herbaceous planting quadrats in five urban parks in Guangzhou, China, from March 2025 to February 2026, with three surveys per season per quadrat and a 30 min observation of flower visitors during each survey. Seasonal differences were assessed using Friedman tests on quadrat-level seasonal summaries. Associations involving visitor diversity and richness indices were examined using linear mixed-effect models with random intercepts for park and quadrat within park. Visit counts were analyzed using negative binomial regressions with standard errors clustered by quadrat. Mean floral cover declined from spring (25.4%) to winter (12.9%), and recorded visits by flower-visiting bees and butterflies followed a similar seasonal pattern (42,233 and 15,255 visits in total, respectively; spring maxima and winter minima). Floral cover was positively associated with bee and butterfly diversity, richness and visitation in 13 of the 16 season × response combinations of the mixed models and in all eight season × taxon combinations of the count models (standardized β = 0.17–0.36), while season × predictor interactions were non-significant for individual predictors (11 of 12 tests), indicating limited support for a systematic seasonal shift in the strength of any individual association. These findings characterize seasonal variation during a single annual cycle in the surveyed parks; because the study is observational and covers one year, they provide hypotheses rather than demonstrated management outcomes, and highlight continuity of floral resources as a topic for further monitoring.