青藏高原南部南木林地区树木径向生长对气候因子的响应

树木年轮定年准确、连续性强、分辨率高，并且易于获取复本，已经成为过去气候变化重建的主要手段之一。通过分析青藏高原南部南木林地区大果圆柏的树木年轮宽度变化及其对气候因子的响应，发现树木生长季前期的温度与树木径向生长变化呈正相关关系，而夏季温度与树木径向生长呈负相关关系；年总降水量（上年7月到当年6月）是当地树木径向生长的主要限制因子，相关系数为0.66（P<0.01），表明南木林地区树轮宽度变化可以指示该地区年总降水量变化。南木林树轮年表（1560—2008年）的突变检验结果显示，该年表在年代际尺度上存在1627年和1829年左右的突变点，表明南木林地区降水量在过去499 a间经历了两次突变。对树木年轮标准化年表的功率谱分析表明，南木林树轮记录具有150 a、100 a、75 a、60 a、50 a以及3.7 a 和3.06 a的显著周期，其中3.7 a和3.06 a周期可能与ENSO有关。

Establishment of Tree-ring Chronology and its Response to Climate Factors in Nanmulin Region,Southern Tibetan Plateau

The Tibetan Plateau, located in subtropical latitudes and having a very special topography, is very sensitive to climate changes. In this study, a new tree-ring chronology of Tibetan juniper (Sabina tibetica) spanning the period of 1375—2008, was established in the Rikaze region on southern Tibetan Plateau. Correlation and response analysis was applied for relation between ring-width index and climate factors. Results showed that positive correlation was found between the tree-ring width and the monthly temperature preceding growth seasons, whereas negative correlation was found between the tree-ring width and the summer temperature of the current year. There was a correlation coefficient of 0.66 (P<0.01) between annual precipitation (prior July to current June) and the ring-width index, indicating that annual precipitation could be the controlling factor for tree growth on southern Tibetan Plateau. The tree-ring chronology in Nanmulin region can be regarded as an indicator of annual precipitation and can reflect the wet-dry fluctuations over the period of 1560—2008 A.D. Abrupt changes around 1627 and 1829 were detected using the methods of Mann-Kendall and moving t-test at multi-decadal scale. Power spectrum analysis revealed significant cycles of 150 a, 100 a, 75 a, 60 a, 50 a, 3.7 a and 3.06 a over the past 499 years.