The Early- to Latewood Transition Phenology Is Asynchronous between the Different Parts of Abies forrestii var. smithii in Jiaozi Mountain, Yunnan, China

Phenological synchronicity of different tree parts and habitats can provide valuable insights into the physiological relationships regulatory factors phenologies. The earlywood (EW) to latewood (LW) transition xylem is a critical process closely related key functions processes trees. This study investigated phenology phase EW–LW in branches stems Smith fir (Abies forrestii var. smithii Viguié & Gaussen) along an altitude gradient (3600 m, 3800 4000 m) Jiaozi Mountain, Yunnan, China, 2021. aimed test hypothesis that earlier than stems, but elevation does not affect time. We monitored dates weekly using microcores then correlated them climatic conditions developmental processes. Our findings revealed timing varied among was synchronized across elevations. Furthermore, always occurred stem, difference narrowed with increasing altitude. mainly influenced by photoperiod, which plays crucial role as signaling factor. Additionally, crown more sensitive environmental changes stem. time less branches. Therefore, our results suggest regulated factors, photoperiod may indirectly regulate trees factor, thus regulating provides new regulation climate sensitivity ring formation.