昌岭山两个优势树种径向生长对气候变化的响应

在气候变暖背景下，树木径向生长对气候变化的响应存在不稳定性。利用采自祁连山东部余脉昌岭山两个优势树种油松和青海云杉的树轮样芯，建立树轮宽度标准年表，通过分析树轮宽度年表与气候要素的相关关系，探讨两个树种径向生长对气候变化的响应。结果表明：（1）油松年表比青海云杉年表包含更多的气候信息，其平均敏感度、标准差、信噪比和样本对总体的代表性等统计量均高于青海云杉标准年表。（2）气候要素对不同树种径向生长限制程度不同，油松径向生长主要与降水（前一年9月和当年3-8月）和气温（前一年9月）有关，但对降水的响应更为敏感，而青海云杉径向生长则受到气温（当年9月）和降水（前一年9月、当年3月和7月）的共同作用。（3）气温突变后，油松和青海云杉年表与各气温要素的相关性显著增强，而青海云杉年表与气温要素的相关性变化更明显，指示了青海云杉径向生长对气温的响应更不稳定。（4）生长季平均最低气温的升高诱导的干旱胁迫是油松和青海云杉树木径向生长-气温响应变化的主要原因。

Responses of radial growth of two dominant tree species to climate change on Changling Mountain

In the context of global warming, there may be different responses of radial growth of tree species to climate change. In this paper, tree-ring cores were collected from two dominant trees, Pinus tabulaeformis and Picea crassifolia, on Changling Mountain located in the eastern region of the Qilian Mountains. In total, 147 cores were extracted from 70 Pinus tabulaeformis trees, and 111 cores were extracted from 54 Picea crassifolia trees. All cores were collected from healthy, living trees. Two tree-ring width chronologies were developed, and we analyzed the correlation relationship between the two tree-ring width chronologies and climate variables (temperature and precipitation) to determine the different responses of radial growth of two tree species to climate warming. Additionally, the Mann-Kendall method was used to analyze the abrupt change point of the mean temperature and the abrupt change of radial growth of Pinus tabulaeformis and Picea crassifolia to climate and this was discussed. Our results indicated that:(1) The chronology of Pinus tabulaeformis contained more climate information than the chronology of Picea crassifolia, and its mean sensitivity, standard deviation, signal to noise ratio, and expressed population signal were higher than those of the Picea crassifolia chronology; (2) The climatic factors had different degrees of limitation to the radial growth of the two tree species. The radial growth of Pinus tabulaeformis was primarily related to precipitation (September of the previous year and March to August of the current year) and temperature (September of the previous year), but it was more sensitive in its response to precipitation. However, the radial growth of Picea crassifolia was accompanied by the combined effect of temperature (September of the current year) and precipitation (September of the previous year, March and July of the current year); (3) After the abrupt temperature, the correlation between the chronologies of Pinus tabulaeformis and Picea crassifolia and the temperature elements significantly increased, but the correlation between the chronology of Picea crassifolia and temperature was more obvious, which indicated that the radial growth of Picea crassifolia had greater instability in its response to temperature; (4) The drought stress induced by rising the mean minimum temperature in the growing season was the main reason for the change in the radial growth-temperature response of Pinus tabulaeformis and Picea crassifolia.