Temporal dynamics of shoot and xylem growth in Chinese fir: Implications for carbon allocation

Understanding the coupling relationship between shoot and xylem growth is critical for understanding tree growth strategies and further assessing the carbon sequestration potential of forest ecosystems. In this study, we monitored the intra-annual growth dynamics of the xylem and shoot of Chinese fir (Cunninghamia lanceolata (Lamb.)) in subtropical China from 2022 to 2023. The results showed that the onset of bud and shoot growth was significantly later than that of the xylem formation in 2022 and 2023. Compared with 2022, the increased shoot growth in 2023 corresponded to a higher xylem production. Also, the end date of shoot growth was negatively correlated with the number of earlywood cells and xylem cells, indicating that earlier termination of shoot growth might promote xylem growth by increasing earlywood growth. These results provide a basis for predicting the growth of xylem and shoots of Chinese fir under future climate change and useful guidance for achieving ecological protection and sustainable development goals.