Response of radial growth of tree species Dahurian larch (Larix gmelinii) and Mongolian pine (Pinus sylvestris var. mongolica) to extreme climate in the northern part of the Greater Khingan Range, China

Abstract

In this study, we adopted tree ring climatology to understand the differences in the response of the radial growth of two typical tree species to extreme climate indices in the Greater Khingan Mountains region, Northeast China. In particular, we collected 231 samples of Dahurian larch (Larix gmelinii) and Mongolian pine (Pinus sylvestris var. mongolica) from four sampling points in the in the Genhe region of the Greater Khingan Range Mountains to establish a standardized chronology of Dahurian larch and evaluate extreme climate indices and their trends. Pearson correlation analysis was employed to analyze the growth response of Dahurian larch and Mongolian pine pine to extreme climatic factors at each sampling point, and the similarities and differences in the radial growth characteristics of each tree species and their response to climatic factors before and after a sudden change in temperature were investigated. The results revealed that after the sudden change in climate, the radial growth of larch and Mongolian pine pine exhibited the same upward trend that was more significant at high altitudes, while the radial growth of Mongolian pine pine had a more obvious upward trend at low altitudes. Correlation analysis with climate elements demonstrated that in May of the current year, the radial growth of high-elevation Dahurian larch was significantly positively correlated (p < 0.05)with the minimum temperature minima, while the radial growth of larch was significantly positively correlated with temperature, and the minimum temperature minima, maximum temperature minima and number of warm night days were significantly positively correlated with the number of cold day days. Following the sudden change in temperature, in May of that year, the radial growth of low elevation larch exhibited a significant positive correlation with temperature, a significant positive correlation with the maximum temperature minima and number of warm night days, and a significant negative correlation with the number of cold day days. Moreover, the radial growth of Mongolian pine showed a significant positive correlation with the number of warm night days and minimum temperature minima. After the abrupt climate change, the radial growth of trees in the low elevation areas of Greater Khingan Range were all inhibited by the high temperature in summer, while with the continuous increase of global temperature, the drought stress induced by the high temperature was the main factor inhibiting the growth of high-elevation larch. This study demonstrates that under global warming, the Greater Khingan Range area is becoming increasingly unsuitable for the growth of larch, the distribution area of the natural forest of Mongolian pine may expand, and the distribution area of natural larch forests may decline.