Greening can usually have a cooling effect on urban space; but is this law also applicable to coastal sloping urban space? The coastal urban space of Qingdao Haizhifeng Square, with a sloping topography, was the area we selected to study. The study area contained two parts: a coastal green space and a residential area. ENVI-met was used to create six scenarios. Different lawns, black pine and ash were planted in the two areas to study the cooling effect. The results showed that the closer the area was to the sea, the better the thermal comfort. In both the coastal green area and the residential area, trees increased the PET of the site, and the higher the LAI of the trees, the more obvious the thermal effect. At 15:00, the hottest time during the summer, the highest PET at pedestrian height was lowest in the scenario without trees, reaching 28.3 °C, and the highest was with full ash, reaching 34.3 °C. At the same time, the average difference in PET between the two scenarios was 1.4 °C. The highest PET at pedestrian height was generated in the area of the building away from the sea breeze, especially in the case of the sloping topography behind it or dense street trees on the urban road. Finally, it was concluded that, in urban spaces with a coastal slope topography, lawns should be planted in the coastal green part and low LAI trees in residential areas, and shade trees should not be planted on the coastal walkway. This afforestation strategy can provide a basis to formulate a strategy for promoting the design of regions with similar geographical and climatic conditions in the future.

Flowering cherry (Cerasus sp.) are significant spring-blooming trees. However, the short blooming period and the rarity of early and late-flowering varieties limit their use in gardens in northern China. The experiment incorporated annually early-flowering species such as Cerasus discoidea, Cerasus pseudocerasus ‘Introtsa’, Cerasus dielsiana, Cerasus campanulata ‘Youkou’, Cerasus yedoensis ‘Somei-Yoshino’, and Cerasus spachiana f. ascendens, as well as twice-a-year flowering species like Cerasus subhirtella ‘Autumnalis’ and Cerasus subhirtella ‘Accolade’. We observed the timing of natural events and growth measurements for specific plants over a span of two years. This research involved a thorough examination of their ability to withstand cold temperatures, considering their physiological aspects. We examined the levels of nutrients and hormones in the flower buds at various stages of development in plants that bloom yearly and every two years. The findings indicated that C. subhirtella ‘Autumnalis’ is adaptable, offering the lengthiest autumn blooming phase lasting 54 days. The hierarchy of cold tolerance was as follows: C. pseudocerasus ‘Introtsa’ > C. discoidea > Cerasus × subhirtella ‘Autumnalis’ > C. dielsiana > C. ‘Youkou’. Furthermore, the soluble protein content in leaves increased before autumn flower buds’ sprout of twice-a-year flowering varieties but declined in C. yedoensis ‘Somei-Yoshino’ within the same time. We determined that changes in nutrient content significantly contribute to the autumn opening of C. subhirtella ‘Autumnalis’ robust short branch flower buds. During the final phase of flower bud development, the rise in trans-Zeatin-riboside (ZR) and indolacetic acid (IAA) promotes the initiation of the first flowering period in C. subhirtella ‘Autumnalis’ prior to its mandatory hibernation. The occurrence of secondary flowering involves a multifaceted regulatory process. These findings serve as valuable references for delving deeper into the mechanisms governing cherry blossom formation and secondary flowering.

Cherry blossom trees are iconic ornamental plants of the spring known for their vibrant colors and elegant forms. However, their short flowering period limits their ornamental value. Prunus subhirtella ‘Autumnalis’ is notable for its ability to flower a second time in autumn. Study of the secondary flowering of this variety may offer insights into the development of cherry blossoms. Here, we studied the secondary flowering of Prunus subhirtella ‘Autumnalis’ by collecting three types of flower buds: the terminal buds of long branches in autumn (LB), the basal buds of short branches in autumn (SB), and flower buds in spring (FB). Transcriptomic and metabolomic analyses were then conducted on autumn flower buds to identify key metabolic pathways associated with secondary flowering. These pathways were primarily involved in nutrient accumulation and plant hormone biosynthesis. We then quantified changes in indole-3-acetic acid (IAA), abscisic acid (ABA), jasmonic acid (JA), and gibberellic acid (GA₃), as well as levels of soluble protein, soluble sugar, and starch in flower buds. Correlation analysis indicated that IAA was necessary for flower bud development; ABA was weakly correlated with secondary flowering; and JA was significantly negatively correlated with secondary flowering. The GA₃ content was higher in LB than in SB and was significantly positively correlated with secondary flowering. Additionally, nutrient levels were higher in LB than in SB, suggesting that the accumulation of sufficient nutrients supports the second bloom. Correlation analysis revealed that ABA and GA₃ levels were positively correlated in flower buds, but GA₃ was negatively correlated with JA levels. This study provides a theoretical basis for understanding the molecular and physiological mechanisms underlying the secondary flowering phenomenon in Prunus subhirtella ‘Autumnalis’ and offers valuable insights for extending the ornamental period of cherry blossom trees.