Regulation of tree crown phenology and fruit set of Cinnamomum kanehirae Hayata, an endangered evergreen tree in Taiwan

Regulation of tree crown phenology and fruit set of Cinnamomum kanehirae Hayata, an endangered evergreen tree in Taiwan

Phenological pattern of forest trees reveals climatic controls on phenophases and fruit development, hence providing key information for managing endangered species. We aimed to investigate tree crown phenology and fruit development of evenaged, dominant and codominant trees and to integrate the results with our study of wood radial growth of Cinnamomum kanehirae (Tsai et al., 2018). We conducted a 3-year ground-based observation of leaf, flower and fruit phenology. The fruit set and development were compared among 3 comparison groups: leafless inflorescence, leafy inflorescence and defoliated leafy inflorescence. The reproductive growth of C. kanehirae was present only in dominant trees. Dominant trees saw leaf flushes twice a year, while codominant trees once or twice. The overlapped spans of reproductive and vegetative growth implied resource competitions between these two phenophases and might cause fruitlet self-thinning in March and premature abortion in Autumn. Fruit development was correlated to the number of nearby ordinary leaves instead of inflorescence leaves. Reduced sunshine hours in autumn, 2011 may lead to the delayed flowering and truncated wood growing season of dominant trees in 2012. The different reproductive ability between tree social classes and the response of floral phenology to sunshine hours suggest important roles of light availability in fruit nursery.