关键词: 亚高山森林, 树木年轮, 径向生长, 气候变化

Abstract: We collected tree core samples from the dominant tree species Pinus armandii, Pinus tabuliformis, and Quercus aliena var. acuteserrata in the Dagou watershed of Maoxian County, Sichuan. Combined with long-term meteorological observation data from the Maoxian Mountain Ecosystem Positioning Research Station of the Chinese Academy of Sciences (CAS), we developed standard tree-ring width chronologies to investigate the radial growth responses of these species to climatic factors over the period of 1989-2021. There were significant increasing trends in both annual mean temperature and mean minimum temperature in the Dagou watershed over the past 40 years, with the most pronounced warming in spring. Annual precipitation exhibited a fluctuating decline from 1989 to 2006, and then it increased significantly at a rate of 28.26 mm·a^-1, while winter precipitation decreased markedly. P. armandii and P. tabuliformis exhibited similar trends in basal area increment (BAI), increasing steadily before 2014 at average rates of 146.68 and 169.41 mm²·a^-1, respectively, after which both species showed a decreasing trend. In contrast, the BAI of Q. aliena var. acuteserrata continued to increase rapidly, with a maximum average growth rate of 164.23 mm²·a^-1 over the period 1998-2018. The radial growth of P. armandii was primarily influenced by temperature, showing significant positive correlations with the mean minimum temperature in July and August of the previous year, as well as with both the mean minimum temperature and mean temperature in March and April of current year. Additionally, its growth was significantly positively correlated with precipitation during the current growing season, specifically in June and September. The radial growth of P. tabuliformis showed a significant negative correlation with the mean maximum temperature in June of the current year and with precipitation during the previous growing season (June-October). The radial growth of Q. aliena var. acuteserrata was significantly positively correlated with mean temperature in spring and maximum temperature in summer, but negatively corre-lated with winter precipitation. In the context of continuously increasing temperatures, particularly the rising spring temperatures and declining winter precipitation, Q. aliena would exhibit stronger growth adaptability and competitive potential.

Key words: subalpine forest, tree ring, radial growth, climate change