Assessment of the impact of air temperature variations on the duration and abundance of flowering of Abelia × grandiflora ‘Little Richard’ in the context of urban planning and design

Variations in temperature have the potential to either enhance or disrupt ecological systems, yet little is known about how the plasticity of Glossy Abelia, under conditions of localised climate change, can facilitate urban planning and design. Therefore, this study focuses on changes in the duration and abundance of flowering of Abelia × grandiflora ‘Little Richard’ in Lep Izgled Park in Belgrade during the period 2023–2025. Observations were carried out using the extended BBCH scale, with recorded dates converted into day-of-year values. The accumulated heat sum for flowering onset, full flowering, and end of flowering was determined based on daily maximum and minimum air temperatures. Flowering abundance was evaluated using a 0–5 scale, where 0 indicates the absence of flowering and 5 indicates maximum flowering. The study employed descriptive statistics, the Spearman rank test, the Mann–Kendall trend test in conjunction with Sen’s slope test, and regression analysis. The results confirm that air temperature influences both the duration and abundance of flowering. The year factor proved to be significant, with 2024, identified as the globally warmest year, exhibiting the longest flowering phenophase, while flowering abundance varied depending on daily maximum and minimum air temperatures. The distribution of flowering abundance and shifts in phenological patterns suggest that the responses of Glossy Abelia represent adaptations to local conditions. This study also provides a framework for modelling the potential effects of temperature changes on the dynamics and abundance of flowering on both local and global scales. The research highlights key events in flowering patterns in order to emphasise the influence of air temperature on changes in the urban phenology of glossy abelia, with the aim of supporting the operationalisation of urban planning and park design.