Relationship between Flowering Phenology and Functional Traits of 67 Woody Plants in the Ningbo Botanical Garden

Abstract

Flowering phenology is closely related to plant reproduction, and its response to climate change is obvious; therefore, revealing its influencing factors and interspecific changes has become an important issue in global change ecology and physical geography. Previous studies have reported that interspecific changes in flowering phenology are affected by climatic factors (such as temperature and precipitation) and related to plant functional traits. However, the magnitude of the correlation between functional traits and flowering phenology varies greatly among different regions and climatic zones, and the relationship between them remains unclear. In this study, to explore whether functional traits affect interspecific changes in the flowering phenology of subtropical evergreen broadleaf species, 67 woody species in the Ningbo Botanical Garden were chosen as the study objects. Four types of flowering phenological characteristics (initial flowering time, full bloom time, falling flower time, and duration of the flowering period) were observed. General statistical analyses (i.e., maximum, minimum, mean, coefficient of variation, and frequency) were used to test the distribution patterns of flowering phenology. Four statistical methods (independent samples t-test, one-way analysis of variance, linear fitting, and generalized linear mixed effect regression models) were used to analyze the differences in flowering phenology between different types (tree vs. shrubs, different types of flower color, and fruit type) and the contributions of different functional traits (i.e., potential maximum tree height, life form, flower color, and fruit type) to the changes in flowering phenology. The results showed that: (1) the initial flowering time, full bloom time, falling flower time, and duration of the flowering period of 67 woody plants were March 28 ± 21.64 d, March 30 ± 27.02 d, April 15 ± 30.78 d, and 23.82 ± 13.31 d, respectively. (2) The initial flowering time and full bloom time of trees were significantly earlier than those of shrubs (P 0.05). The standard deviation of the flowering phenology of trees was lower than that of shrubs, indicating that the flowering phenology of trees was more stable than that of shrubs. (3) The results of generalized linear mixed-effect regression models showed that the effects of the four functional traits on flowering phenology differed. More specifically, flower color significantly affected falling-flower time (P < 0.01). The falling flower time of colored flowers was earlier than that of white flowers. Life form and potential maximum tree height significantly affected the duration of the flowering period (P < 0.01). Plants with higher potential maximum heights have longer flowering periods. In conclusion, our study indicates that the flowering phenology of 67 woody species in the Ningbo Botanical Garden is affected by functional traits. However, the magnitude of the influence is related to the type of functional trait. Flower color and potential maximum tree height contributed more to interspecific changes in flowering phenology than other functional traits. Our results help us understand the variation in flowering phenology among woody species in subtropical regions and provide a new perspective for the theoretical exploration of phenology.

Keywords

• woody plants
• flowering phenology
• life form
• flower color
• fruit type
• maximum potential height
• subtropical area
• ningbo