To clarify the radial growth dynamics of Abies nephrolepis across different diameter classes in the Changbai mountains, reveal the response patterns and differences in growth to climatic factors among trees of various diameter classes, and to provide a scientific basis for forest management under climate change.

Three different diameter classes of [15, 25), [25, 35) and [35, 45) cm were continuously monitored by radial growth measuring instruments. The growth season was determined by the zero growth method, and the radial growth sequence was extracted. The dynamic relationship between the radial increment of different diameter classes and climate factors was explored by sliding correlation analysis.

1) There was a significant difference in the daily radial increment sequence among [25, 35) cm, [15, 25) cm and [35, 45) cm in the growing season of 2022 (P<0.001). The total radial growth and average growth rate increased with the increase of diameter class, and the maximum growth rate of the [25, 35) cm diameter class was the fastest. The maximum growth rates of [25, 35) cm and [35, 45) cm were at the beginning of the growing season, while the maximum growth rate of [15, 25) cm was at the middle of the growing season. 2) In the growing season of the year, there was a strong dynamic consistency between the radial growth of different diameter classes of A. nephrolepis and the response of climatic factors, but there were differences in the strength of the relationship with climatic factors at different stages, and the climatic factors with significant positive and negative correlations were different. As the growing season progresses, the daily radial increment of each diameter class of A. nephrolepis is similar to the dynamic response trend of average temperature and soil temperature. The radial growth of A. nephrolepis [15, 25) cm was promoted by mean air temperature and 10 cm soil temperature, and was more inhibited by soil water content and air relative humidity. The negative correlation between radial growth and photosynthetically active radiation at [25, 35) cm was stronger. The radial growth of A. nephrolepis [35, 45) cm was more strongly inhibited by average temperature and 10 cm soil temperature, and also showed a stronger negative correlation with saturated water vapor pressure deficit, indicating that this diameter class tree was more vulnerable to temperature and drought stress, but it showed stronger adaptability and regulation ability to photosynthetically active radiation.

The radial growth of A. nephrolepis is affected by a variety of climatic factors. The physiological processes and competition of different diameter A. nephrolepis are different, which makes their radial growth dynamics and the response relationship with climatic factors different. Through the study, the response dynamics of various climatic factors and the radial growth of different diameter classes of A. nephrolepis were obtained. Differentiated conservation measures such as monitoring temperature and humidity dynamics, paying attention to the health status of diseased and weak plants, and preventing and controlling high temperature and drought stress should be taken for [15, 25), [25, 35), and [35, 45) cm Abies nephrolepis to maintain growth stability and carbon sequestration.