Stem radial growth dynamics of Pinus sylvestris var. mongolica and their relationship with meteorological factor in Saihanba, Hebei, China

Abstract

Aims Trees are the basic components of forest ecosystems, and their growth is affected by meteorological factors. It is important to explore the response mechanism of forest ecosystems in this region to climate change if radial growth dynamics of dominant tree species and their relationship with meteorological factors are determined. Furthermore, previous studies on tree growth were mostly based on tree-ring chronology, whereas shortterm studies on the stem radial growth dynamics of trees are scare. Therefore, this study aims to investigate the daily and seasonal dynamics of radial growth in Pinus sylvestris var. mongolica and its relationship with meteorological factors. Methods In this study, dendrometer increment sensor was used to monitor the stem radial dynamic changes of P. sylvestris var. mongolica for three years from 2016 to 2018 in the Saihanba, Hebei Province, China. Important findings Due to the water absorption and transpiration of the stems, the diurnal variation of the stem radial can be divided into four periods: Spring germination period; summer growth period; autumn-winter alternating period; winter dormant period. Stem radial growth begins at early April in each year during water recovery from early April to mid-May. The fast-growing stage occurred from mid-May to mid-July. From mid-July to mid-October, trees entered a slow-growing stage. The radial growth tended to stop during mid- and late-October. Temperature was the main meteorological factor influencing the stem radial growth. On the time scale of one day, the stem radial growth was mainly affected by temperature during the rapid growth stage, but by rainfall and air temperature during slow growing stage. On the time scale of 15 days, only temperature had a significant effect on the stem radial growth. Under the conditions of extreme low temperature and drought, our results provide important reference for the growth status of P. sylvestris var. mongolica in semi-arid areas.