利用树轮资料重建青海都兰地区过去1835年的气候变化

根据青海都兰地区树木年轮样本，建立了上前我国最长的年轮年表序列（１８３５a），系 统地与所在地区气候资料进行了综合分析。通过响应函数计算得出，该年表对温度因子的反映更为第三一些。在响应面分析中发现，温度、降水与年轮宽度的关系呈现出随温度和降水的不同而不同。在温度低而降水量少的情况下，其线性相关性明显；但在温度较高和降水量较多时，树轮与两要素间的关系就显得不明显。另外，还对该年表玮秋季平均温度的关系进

Reconstruction of A 1 835 a Past Climate for Dulan, Qinghai Province, Using Tree-Ring

A 1 835 a tree-ring chronology from the Qilian juniper(Sabina Przewalskii) has been estab- lished based on 135 specimens. The tree-ring data from tree core were collected at Ela Mountains, rang- ing from 3 100 to 3 700 m a.s.l. In Dulan, Qinghai Province. The studied area is local at the northeast of Tibetan plateau, and between Kunlun and Qinghai-Nanshan Mountains, with average elevation of above 3 500 m. The average annual precipitation in this region is 180-200 mm and the annual mean tem- perature is 0.3℃, thus it is a typical dry, high and cold area. The tree-ring series were cross-dated and measured using standard techniques, at the Laborato- ry of Tree-ring Research in the University of Arizona. The tree-ring chronology was compared directly to the monthly temperature and precipitation data from the closest Dulan meteorological observato- ry near the sampling sites. Response function and linear regrssion analyses indicate that there are better relation of tree-ring width to mean temperature of September-November and precipitation of March- June. Response surface analyses indicate that there is a good linear regrssion between tree-ring width and climate elements while it is low temperature and few precipitation , and a bad relation of that when it is high temperature and large precipitation. At the same time, based on ground temperature, soil containing water and sunlight in the studied area, it is educe that relation of tree-ring width and mean temperature of autumn, which indicate that the growing season of Ju- nipers is summer and autumn in the high altitude area of the Tibetan Plateau. Therefore mean temperature of September-December can be reconstruced in Dulan using tree-ring chronology.