Intra-annual stem radial increment patterns of Chinese pine, Helan Mountains, Northern Central China

Key message We investigate the intra-annual growth patterns of Chinese pine in Helan Mountains, confirming that regional water status plays a dominated role in stem radial increment. The associations between environmental conditions and stem radial increment (SRI) are useful for assessing a species’ growth response to climate change. Intra-annual SRI dynamics of Chinese pine ( Pinus tabulaeformis ) were monitored half-hourly by automatic point dendrometer during the growing season (May–September) in 2016 and 2017 at two altitudes in the Helan Mountains, northern central China. Here, we compared the seasonal growth patterns between two altitudes and 2 years. Trees at low altitude are characterized by earlier cessation, shorter growing season, and lower growth rate, resulting in less annual growth, which may reflect the greater drought intensified by rising temperature at low altitude. June precipitation significantly affected tree growth rate. The xylem growth was active when daily mean air temperature was 9.9 °C at our study region for P. tabulaeformis in an arid environment. During the growing season, daily stem radial increment showed a significantly positive correlation with precipitation and a negative correlation with daily air temperature at all altitudes. Climatic variables associated with tree water status, namely precipitation, vapor pressure deficit, and relative humidity, played important roles in daily stem radial increment as the same result as a linear mixed model. These factors drive the complex physiological processes of stem radial increment by influencing the moisture available to the tree.