Abstract:Xylem growth of trees plays an important role in slowing global warming. In order to understand the intra-annual xylem growth dynamics of subtropical Castanea henryi and its response to climate in Dinghushan mountain in south China, the xylem of C. henryi was continuously monitored by microcore sampling technology, the xylem growth in 2015 was fitted by generalized additives models, and the relationship between the xylem growth rate and climate factors was analyzed by using mixed-effect models. The results showed that xylem growth of C. henryi in Dinghushan Mountain kept almost whole year of 2015, and showed significant seasonal differences. The xylem grew rapidly before 200 days of 2015 (early growing season), and showed a down trend in growth rate after 300 days of 2015 (late growing season). The xylem growth rate during early growing season was positively correlated with temperature and photosynthetically active radiation, but that between xylem growth rate and climate factors during late growing season was not significant. So, it was reflected that there were seasonal differences in xylem formation and its regulating mechanism of south subtropical broad-leaved tree C. henryi of China, showing the adaptability of xylem formation to the environment. These could provide data support for deeply understanding and predicting of trees growth in subtropical forest ecosystem under the background of climate change.