Responses of radial growth of Juniperus przewalskii to different droughts over the northeastern Tibetan Plateau, China

Abstract

To study the responses of radial growth of Juniperus przewalskii to climate factors of the different periods (pre-growing season (February-April), growing season (May-July)), and the vulnerability (resistance, RT; recovery, RC) of J. przewalskii to different drought events (precipitation, temperature and the both caused), we used tree ring width data of J. przewalskii from 17 sampling sites across the northeastern Tibetan Plateau to analyze the correlation between radial growth and climate factors of different periods, and the vulnerability in different drought events. The results showed that radial growth of J. przewalskii had significant positive correlation with drought index and negative correlation with temperature in the growing season (P<0.1). The vulnerability of J. przewalskii to drought events of different periods had significant difference. In the pre-growing season drought events, the RT of J. przewalskii at low altitude was 2.3% higher than that at high altitude, the RC of J. przewalskii at low altitude was 25.1% lower than that at high altitude. For drought events in the growing season, the RT of J. przewalskii at low altitude was 23.7% lower than that at high altitude, the RC of J. przewalskii at low altitude was 107.1% higher than that at high altitude. The mean RC(1.68) of J. przewalskii in precipitation-caused drought events was strong, while the mean RT(1.43) of J. przewalskii in temperature-caused drought events was strong. The growth of J. przewalskii, especially for that at low altitude, would be largely limited by drought caused by global warming in the future.