Studying the radial growth of trees is crucial for reconstructing past climatic conditions and predicting the future adaptability of forests to climate change, and for developing sustainable forest management strategies.

The Gompertz model was used to fit the growth curve of Abies nephrolepis to determine the time of growing season. The periodic cycle method, daily value method and zero growth model were used to extract the daily radial variation, and the correlation between the radial variation in the growing season and environmental factors such as air temperature and humidity, soil temperature and humidity was processed and analyzed.

1) The growth season of Abies nephrolepis began in early May and ended from late July to August. The maximum growth rate appeared before the summer solstice; 2) The annual radial variation sequence of Abies nephrolepis has obvious seasonal characteristics. The rapid water replenishment expansion in early spring and the freeze-thaw cycle of stem in winter leads to higher radial variation, while the long period caused by continuous cooling in summer and continuous contraction of low temperature in winter makes the daily radial variation of periodic cycle method significantly different from other methods; 3) During the growing season, sufficient rainfall and low saturated vapor pressure deficit were the key factors to promote the daily radial growth of Abies nephrolepis, while the minimum temperature at night significantly affected the expansion growth process of radial variation. The daily value method and the zero growth model emphasize the synergistic effect of multiple hydrothermal conditions such as average air temperature, soil temperature and humidity, while the periodic cycle method emphasizes the role of water factors (saturated vapor pressure difference, rainfall), and the periodic cycle method has a higher interpretation of growth variables about 60%.

Rainfall and saturated vapor pressure difference were the dominant environmental factors in the growing season of Abies nephrolepis in the study area, followed by the highest air temperature and soil moisture. The periodic cycle method is more suitable for the study of short-term tree radial growth in this area than other methods.

To analyze the impact and contribution rate differences of factors such as climate, site conditions, stand competition, and stand structure on the radial growth of early and late wood and tree-ring width in coniferous species, aiming to understand the response patterns of tree radial growth to multiple factors. This will provide a scientific basis for the study of growth dynamics and refined management of coniferous mixed forests in the Changbai mountain region.

Based on tree-ring cores and remeasurement data of Picea jezoensis, Abies nephrolepis, and Pinus koraiensis from fixed plots in Jingouling forest farm, a logistic function was selected as the base model. Stepwise multiple regression and variance inflation factor (VIF) analysis were applied to screen significant variables. The retained variables were incorporated into the base model using re-parameterization, and simultaneous equations models for earlywood, latewood, and total radial growth of each species were developed via seemingly unrelated regression (SUR). Model validation was conducted using independent test datasets. Hierarchical partitioning analysis was employed to quantify the contribution rates of climatic, competition, site, and stand structural factors to radial growth.

The basal area increment (BAI) of all three species followed an asymptotic trend with increasing cambial age. The simultaneous equations models exhibited high predictive accuracy (coefficients of determination [R²] = 0.813-0.917). Key climatic drivers included temperature and moisture during the pre-growing season, July, and winter, which positively influenced radial growth. In contrast, species diversity indices and stand competition factors predominantly exerted negative effects. Site factors (elevation, slope aspect, and gradient) showed positive correlations with growth. The difference in contribution rate indicates that different tree species and wood types are subject to different types of main controlling factors.

This study clarifies the specific response patterns of earlywood and latewood radial growth to various factors in three tree species, which helps provide guidance for formulating more precise management strategies for the coniferous mixed forests in Changbai Mountain.