Intra-annual stem radial growth of Qinghai spruce and its environmental drivers in the Qilian Mountains, northwestern China

Quanyan Tian; Zhibin He; Shengchun Xiao; Xiaomei Peng; Pengfei Lin; Xi Zhu; Xiangyan Feng

doi:10.1016/j.scitotenv.2024.170093

Intra-annual stem radial growth of Qinghai spruce and its environmental drivers in the Qilian Mountains, northwestern China

Sci Total Environ. 2024 Mar 10:915:170093. doi: 10.1016/j.scitotenv.2024.170093. Epub 2024 Jan 13.

Authors

Quanyan Tian¹, Zhibin He², Shengchun Xiao³, Xiaomei Peng⁴, Pengfei Lin¹, Xi Zhu¹, Xiangyan Feng⁵

Affiliations

¹ Linze Inland River Basin Research Station, Chinese Ecosystem Research Network, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, China.
² Linze Inland River Basin Research Station, Chinese Ecosystem Research Network, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, China. Electronic address: hzbmail@lzb.ac.cn.
³ Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, China; Key Laboratory of Eco-hydrology of Inland River Basin, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁴ Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, China; Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁵ Linze Inland River Basin Research Station, Chinese Ecosystem Research Network, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, China; University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 38224885
DOI: 10.1016/j.scitotenv.2024.170093

Abstract

Tree stem radial growth could be used to estimate forest productivity, which plays a dominant role in the carbon sink of terrestrial ecosystems. However, it is still obscure how intra-annual stem radial growth is regulated by environmental variables. Here, we monitored Qinghai spruce stem radial growth over seven years and analyzed the environmental drivers of the intra-annual stem radial changes in the Qilian Mountains at low (2700 m) and high altitudes (3200 m). We found that stem radial growth initiated when the daily mean minimum air temperature reached 1.6oC, while the cessation of stem growth was unrelated to temperatures and water conditions. Initiations of stem growth at 2700 m were significantly earlier than that at 3200 m. Maximum growth rates were observed before the summer solstice at low altitude, whereas at high altitude, the majority of them occurred after the summer solstice. Most variability in annual stem increment (AI) can be explained by the rate (Rm) than by the duration of stem growth (∆t), and 78.9 % and 69.6 % of the variability in AI were attributable to Rm for the lower and upper site, respectively. Structural equation modeling revealed that precipitation (P) could both directly positively influence stem radial increment (SRI) and indirectly positively influence SRI through influencing relative humidity (RH), but the positive effect of P on SRI was higher at low altitude than at high altitude. Daily minimum air temperature (Tmin) was also the main direct diver of SRI, and the positive effect of Tmin on SRI was higher at high altitude than at low altitude. Considering the trends in climate warming and humidification over the past decades, climate changes would result in earlier initiation of Qinghai spruce stem growth and promote the growth through positive response to increased precipitation in low altitude and through elevated temperature in high altitude, respectively.

Keywords: Environmental driver; Growing season length; Growth rate; Qilian Mountains; Stem radial changes.