小兴安岭地区是我国最为典型的原始阔叶红松(Pinus koraiensis Sieb. et Zucc.)林分布区,也是受全球气候变化影响最为显著的区域之一。长时期高分辨率气候记录是理解该区过去气候变化规律的最基础资料,然而由于器测气候数据时间较短,亟须获得长时间尺度的代理气候记录。本研究用树木年轮气候学方法,分析伊春典型阔叶红松林内水曲柳(Fraxinus mandshurica Rupr.)径向生长与气候要素的关系,结果表明:水曲柳径向生长与温度相关性较好,尤其是前一年及当年冬季最低温度,与前一年及当年2~3月的最低温均达到了极显著水平(p<0.01),而与降水相关性较差,休眠期(冬季)温度与生长季(早春、夏秋)温度一样均对北半球高纬度地区落叶阔叶树水曲柳的径向生长有明显的促进作用,冬季水曲柳树体内各种生理生化活动及外界复杂的生物地球化学过程可能对水曲柳生长季的径向生长至关重要。基于年轮指数与前一年2~3月平均最低温度的高相关性(r=0.71, p<0.01),利用线性回归模型重建了伊春1790年以来2~3月最低温度变化。重建方程解释了51.0%的低温变化,经分段法、自助法(Bootstrap)和刀切法(Jackknife)检验,证明该方程稳定可靠。重建序列显示,伊春过去221年中存在7个偏冷期(1790~1791年、1795~1819年、1834~1841年、1851~1854年、1898~1899年、1901~1907年和1959~1982年)和4个偏暖期(1822~1831年、1872~1886年、1923~1955年和1988~2010年),其他时段温度在均值附近波动,变化较小。伊春冷暖变化存在4.8~4.9年和18.3年的极显著周期(p<0.01),温度的周期变化可能与太阳活动、厄尔尼诺-南方涛动(ENSO)、大西洋多年代际振荡(AMO)以及太平洋年代际振荡(PDO)有关。
英文摘要:
Xiaoxing'an Mountain, located in Northeast China, is the most typical distribution area of primary broadleaved-Korean pine forests, and is also one of the most significant areas affected by global climate change. To understand the past climate change and predict it in the future in this region,long-term and high-resolution climate records is critical and essential. Thus, long-term climate proxy is desperately needed due to shorter instrumental records. Here we present a 221-year February-March minimum temperature reconstruction based on tree-ring widths of Manchurian ash (Fraxinus mandshurica Rupr.) at Liangshui National Natural Reserve in Yichun,Northeast China. A total of 46 Manchurian ash cores from 23 living trees were extracted from this area (47.19°N, 128.87° E; 475m a.s.l.) in June, 2011. According to the standard methods developed by the International Tree-Ring Data Bank (ITRDB), these cores were pretreated, cross-dated, measured, detrended and standardized. Then, three chronologies (STD,RES and ARS) of Manchurian ash were developed. Correlation functions between tree-ring index and climatic variables indicate that winter temperature is essential for radial growth of deciduous Manchurian ash at high latitudes of Northern Hemisphere. Winter processes are as important as summer processes in controlling the Manchurian ash radial growth. According to the stronger relationship (r =0.71,p<0.01) between February-March minimum temperature in the previous year and tree-ring index (ARSTANT chronologies),we reconstruct the February-March minimum temperature in Yichun using a simple liner regression model. The reconstruction equation explained 51% of the variance of the minimum temperature (1958~2010). Seven cold periods (1790~ 1791, 1795 ~1819, 1834~ 1841, 1851 ~1854, 1898~1899, 1901 ~ 1907 and 1959~1982) and four warm periods (1822~1831,1872~1886,1923 ~1955 and 1988 ~2010) occurred in this region for the past 221 years. The variations of February-March minimum temperature in Yichun exist 4.8 ~ 4.9a and 18.3a of significant (p<0.01) periods. Periodic changes in minimum temperature may be related to activities of the solar activity, El Nino-Southern Oscillation (ENSO),Atlantic Multi-decadal Oscillation (AMO) as well as the Pacific Decadal Oscillation (PDO).