气候变暖对黑龙江省五大连池兴安落叶松径向生长的影响

【目的】龙门石寨熔岩台地是五大连池火山群演替顶极群落兴安落叶松天然林的主要分布地。探讨近51年(1968—2018年)龙门石寨兴安落叶松树木径向生长对气候变暖的响应特征,进而为了解气候变暖背景下五大连池火山群植被演替趋势提供科学依据。【方法】采用Mann-Kendall检验方法确定研究区近51年气温变化的趋势和可能发生气温突变的年份,运用树轮气候学方法分析1968—1981年和1982—2018年两个时间段兴安落叶松径向生长对气候变化的响应特征。【结果】五大连池近44年(1975—2018年)平均气温呈增加趋势,且1981年为研究区年均气温升高的突变点。气候变暖后兴安落叶松年轮指数和胸高断面积增量都下降,年轮指数呈上升的趋势,而胸高断面积增量处于下降趋势,但均不显著。树木径向生长对于气温升高的响应出现了“分离效应”。水热条件共同控制兴安落叶松树木生长,但气温是径向生长的主要影响因子,气候变暖显著改变了兴安落叶松径向生长与气候因子的响应模式,树木径向生长对年平均气温、年平均最低气温和寒冷指数的响应敏感性显著增强。研究期上一年11月的降水以及当年2、3月和生长季前(4—5月)的平均最低气温是决定兴安落叶松年轮宽度的主要因素。【结论】1981年后五大连池气候显著变暖,气候变暖未显著改变兴安落叶松的径向生长,升温造成的干旱胁迫可能是树木径向生长对气温变化响应的“分离效应”及气候变暖后树木径向生长与气候因子的响应显著改变的重要原因。

Effects of climate warming on radial growth of Larix gmelinii in Wudalianchi,Heilongjiang Province

【Objective】The Longmen stone village lava platform is the main distribution area of the Larix gmelinii natural forest in the community of the Wudalianchi volcano group. In this study, we explored the response of the radial growth of L. gmelinii in Longmen stone village to climate warming over the past 51 years (1968-2018) and provided a scientific basis for the vegetation succession trend of the Wudalianchi volcano group under global warming. 【Method】We performed the Mann-Kendall test to determine the trend of temperature change and the years of possible abrupt air temperature changes over the past 51 years. We also analyzed the response characteristics of the radial growth of L. gmelinii to climate change over two periods (1968-1981 and 1982-2018) using tree-ring climatology. 【Result】We found that the mean air temperature of Wudalianchi has been increasing in the past 44 years (1975-2018) and that 1981 was the mutation point. After global warming, both the ring index and basal area increment of L. gmelinii decreased; the tree-ring index showed an upward trend, while the basal area increment showed a downward trend, but the changes were not significant. The “separation effect” appeared in the response of the radial growth to the increased air temperature. Together, water and temperature controlled the growth of L. gmelinii, but air temperature was the main factor affecting the radial growth. The response pattern of the radial growth to climatic factors was significantly affected by global warming. Meanwhile, the response sensitivity of the radial growth to the annual mean air temperature, annual mean minimum air temperature, and coldness index was significantly enhanced. However, the main factors that determined the ring width of L. gmelinii were the precipitation in November of the previous year and the mean minimum air temperature in February, March, and the pre-growing season of the current year. 【Conclusion】Although the climate warmed significantly in Wudalianchi after 1981, it did not have a significant impact on the radial growth of L. gmelinii. The reason for the “separation effect” and the significant changes in the response of the radial growth to climatic factors may be the drought stress after warming.