哈萨克斯坦阿尔泰山树木径向生长及其对气候要素的响应

针对哈萨克斯坦阿尔泰山南坡西伯利亚云杉（Picea obovata）和西伯利亚落叶松（Larix sibirica）开展树轮研究，建立树轮年表，计算年平均树轮宽度值和年平均断面积生长量（BAI），并分析在1988年发生升温突变前后，这2个树种树轮宽度指数变化趋势，及其树木径向生长对气候因子的响应。结果表明：在升温突变前后，2个树种树轮宽度指数变化趋势一致。但是，在升温突变后，其变化趋势均由不显著增加转为显著下降。即树木径向生长减缓；升温突变后，2个树种树木径向生长对降水的响应有所减弱，而对气温的响应有所增强，并且发生了树轮指数和气候因子间相关性“正负转换”的情况。

Radial Growth of Trees in Response to Climatic Factors in the Altay Mountains,South of Kazakhstan

The response of the radial growth of two tree species to climatic factors before and after a sudden rise of regional temperature in 1988 was analyzed based on the research of Picea obovata and Larix sibirica on the southern slope of the Altay Mountains in Kazakhstan. The results showed that there was a good correlation between the two standardized chronologies of the two tree species, and also a high consistency with the stage of low-frequency change and a high reliability of chronological series change. The GLK values of the two chronologies were high, which indicated that their radial growth was consistent. The radial growth of P. obovata and L. sibirica was faster at their young forest age but slower from the middle forest age to the mature forest age in the study area. The variation trend of tree-ring width index of these two tree species was consistent before and after the sudden rise of temperature. Before the sudden rise of temperature, the tree-ring width index of these two tree species increased unsignificantly with a slow decrease of precipitation and a slow increase of temperature. However, after the sudden rise of temperature, the tree-ring width index of P. obovata and L. sibirica was in a significant decline trend with the slow increase of annual precipitation and annual average temperature. This showed that there was a negative impact of climate change on the growth of trees, and the growth of these two tree species might be slowed down after the sudden rise of temperature. Under global warming, the radial growth of P. obovata and L. sibirica was mainly restricted by temperature, and the influence of precipitation was relatively low. The response of L. sibirica to temperature was slightly stronger than that of P. obovata. Holistically, there was a unsignificant difference in response of the radial growth of these two tree species to climate change. The response of the growth of these two tree species to climatic factors before and after the sudden rise of regional temperature in 1988 was analyzed. The results showed that, during the period from 1960 and 1988, there was a significant negative response of tree-ring width of L. sibirica to the precipitation in May that year, and to the temperature in August last year. There was a significant positive correlation between the radial growth of P. obovata and the precipitation in July of that year, but a significant negative correlation between it and the temperature in August last year. During the period from 1989 to 2016, the response of L. sibirica to the precipitation in May was no longer significant. Instead, there was a significant negative correlation between the growth of L. sibirica and the temperature in May of that year and in August last year. There was a weaker positive correlation and a higher negative correlation between the growth of this tree species and the temperature in growth season, or a change from positive correlation to negative correlation. The significant correlation between the radial growth of P. obovata and the precipitation disappeared. Instead, a negative correlation with temperature strengened, especially in August and October last year. The results showed that the positive response of the tree-ring width of P. obovata and L. sibirica to precipitation decreased but the negative response to temperature increased after the sudden rise of temperature. The response of the radial growth of P. obovata and L. sibirica to climatic factors might different after the sudden rise of temperature.