中文摘要：

嫩江是东北地区最重要的河流之一,了解嫩江长期水文变化规律,对嫩江流域林业、农牧业生产具有重要意义。通过对嫩江上游4个地点兴安落叶松（Larix gmelinii）树轮年表与气候水文数据分析,发现4个地点的平均年表与1～3月平均径流量有着极显著关系。因此,基于树轮宽度重建了嫩江上游1804年以来1～3月平均径流量,重建方程解释了43.9%的径流变异,经检验证明重建结果可靠。重建嫩江径流变化表明：1804年以来,嫩江流域上游1～3月份径流经历了6个偏枯和7个偏丰阶段。同时,嫩江上游径流量存在60、4.3～4.0、3.4～3.2、3.1～2.9和2.3 a的变化周期。在19世纪初至20世纪初嫩江1～3月流量的变化幅度较小,而20世纪中后期变化幅度较大。另外,重建结果与黑龙江省历史记载的旱涝时期比较吻合。

英文摘要：

Nenjiang River is one of the most important rivers in northeast China. It has critical significance for forest- ry management and agriculture and livestock production to understand the long-term hydrological regime in this region. A total of 115 tree-ring cores of Larix gmelinii were collected at four sites （Ali River, Gan River, Keyi River and Nuomin River） in the upper Nenjiang River, the northern Daxing＇an Mountains, China. All cores were visually cross-dated under the binocular microscope. Tree-ring widths were measured to the nearest 0.001 mm with a Velmex measurement system. The cross-dated tree-ring sequences were quality checked by COFECHA program. ARSTAN program was used to de-trend the ring-width sequences with a negative exponential curve or a straight line with negative slope （ or a horizontal line） and four chronologies were developed. Response analysis between four tree-ring chronologies and monthly climatic factors （mean temperature and total precipitation） were conducted. The results show that tree-ring chronologies in the four sites are negatively correlated with temperature in all months of a whole year, while which are positively correlated with precipitation in growing season and negatively correlated with precipitation in non-growing season. These results indicate that water availability is the major limiting factor of tree growth in this region. Therefore, an average tree-ring chronology for four sites was developed to reconstruct the history of streamflow variation for the Nenjiang River. Simple correlations between the average tree-ring chronology and monthly streamflow data show that the average chronology of four sites is significantly correlated with mean January - March streamflow. Therefore, mean January -March streamflow in the upper Nenjiang River since 1804 was reconstructed. In addition, the reconstructed drought and flood periods are relatively identical with the historical records of hydrological variation in Heilongjiang province. The major periods of reconstructe