Objective  Mongolian pine (Pinus sylvestris var. mongolica) is an essential tree species for sandy land management in dry and semi-arid regions of northern China. Clarifying the characteristics of intra-annual radial variations in Mongolian pine and their relationship with climatic factors can provide a theoretical basis for vegetation restoration and plantation management in the Mu Us Sandy Land, Inner Mongolia of northern China, where water stress is significant.

Method In this study, stem radial size changes in Mongolian pine in the Mu Us Sandy Land were continuously monitored for 15 months using automated dendrometers, and the diurnal and seasonal dynamics of radial changes were studied. The relationship between radial growth process and climate factors was investigated using a linear mixed effect model and Spearman correlation analysis.

Result (1) In warm seasons, Mongolian pine’s diurnal stem radial variation pattern showed contraction during the day and expansion during the night; in cold seasons, the opposite was true, with more noticeable daily radial fluctuations in December and January. (2) Stem radial growth began in mid-to-late April, with annual growth finished primarily between May and August. After September, radial growth slowed and eventually contracted. (3) During the entire growing period, daily radial growth rate of Mongolian pine had a significant positive association with relative humidity, precipitation and temperature, but a significant negative correlation with photosynthetically active radiation. However, for different periods, photosynthetically active radiation did not have a significant impact on daily radial growth rate. The relationship between tree water deficit and climatic factors was mostly opposite to daily radial growth rate.

Conclusion The seasonal growth features of Mongolian pine in the Mu Us Sandy Land are predominantly driven by temperature and moisture conditions. The findings contribute to a better knowledge of Mongolian pine growth and climatic influence patterns, and provide scientific reference for vegetation restoration and sustainable management of Mongolian pine plantations in the Mu Us Sandy Land under the background of climate changes.