Intra-annual xylem formation dynamics of Castanopsis hystrix and its response to climate in southern Guangxi, China

To investigate the intra-annual xylem formation dynamics of Castanopsis hystrix and its response to climate factors in a monoculture plantation in Pingxiang City, southern Guangxi, China, this study monitored the xylem formation dynamics and seasonal vessel diameter of nine trees over two growing seasons (2022 and 2023). We used linear mixed model to examine correlations between xylem growth rates and climatic variables. We found that 90 % of xylem cells production of C. hystrix was concentrated during March to October in 2022 and 2023. The xylem growth rate exhibited significant positive correlations with temperature and photosynthetically active radiation recorded 7, 10, and 15 days prior to sampling date and sunshine duration on the sampling date. Specifically, the highest mean vessel diameter at the early phase of growing season corresponded to the peak of xylem growth rate in two years, exemplifying the coordinated mechanism underlying the regulation of tree growth and wood anatomy . We highlighted the critical climatic factors during the growing season and illustrated the correlation between xylem growth and wood anatomy, which offered valuable suggestions for the forest management especially under climate change .