Abstract:

This study examined the rhythmic patterns and temporal shifts in flowering phenology of 48 plant species in Beijing by analyzing observed phenological and meteorological data from 1963 to 2012. Focusing on six key flowering stages and utilizing the Twenty-four solar terms as a temporal framework, authors applied linear trend estimation, correlation analysis, and statistical testing to investigate phenological characteristics, changing trends, and characteristics of climate response. The results showed that: (1) nearly 80% of the species exhibited advancing trends in their flowering phenology, with over half demonstrated significant shifts of 5-25 days earlier in their first, peak and last flowering date (P<0.05). (2) Successive flowering stages for over 70% of species occurred within the same or adjacent solar term. Flowering was most concentrated during spring and summer: flower bud swelling and opening peaked at Hibernator Awakens (HA, 71.8%) and Spring Equinox (SE, 73.9%), inflorescence or flower bud emergence was most frequent during SE and Fresh Green (FG, 58.4%); first and peak flowering dates were most common from FG (54.2%) and Grain Rain (GR, 56.3%); and last flowering dates clustered between GR and Summer Begins (SUB, 54.1%). (3) Flowering duration increased lengthened for 60.4% of species (mean+8d) but shortened for 39.6% (mean-3d). The extension was primarily attributed to an earlier first flowering date (FFD, 43.8%), while shortening mostly was mainly due to an earlier last flowering date (LFD, 33.3%). (4) The average flowering duration across all species ranged from 5 to 80d. Spring-flowering species generally had shorter durations than summer-flowering ones, with 77.1% of spring bloomers completing their flowering within a 15-day period (equivalent to one solar term). (5) 91.8% of the statistical series of the average temperature between the FFD of 48 plant species and the Minor Cold (MIC) to Minor Heat (MIH) showed a negative correlation, with the most pronounced correlations observed during HA, SE and FG (each showing a negative correlation proportion of 95.8%). Spring-flowering species exhibited higher temperature sensitivity than summer-flowering species. Over 90% of spring-flowering species showed a significantly negative correlation (P<0.05) between their FFD and mean temperature during HA, SE and FG. Furthermore, the first flowering date was significant negatively correlated (P < 0.05) with the mean temperature of its average occurrence solar term and the four preceding solar terms. Among these, early-spring flowering species were the most temperature-sensitive, followed by late-spring and summer species. By adopting the perspective of solar terms, this research elucidates the rhythmic patterns of flowering phenology in Beijing, its shifts under climate warming, and its strong temperature dependence. These findings underscore the sensitivity of plant phenology to climate change and provide a scientific basis for adaptive plant management, flowering forecast, and the planning of floral tourism activities within the framework of solar terms.

Key words: Phenology, First flowering date, Flowering duration, Mean temperature, Change trends