关键词: 树木年轮, 降水量, 旱涝, 祁连山

Abstract: The standardized(STD)chronology was established from tree-ring data of Sabina Przewalskii in the middle part of the Qilian Mountains. The correlation was analyzed between the tree-ring index and the precipitation in weather stations, near which the tree ring is sampled. The results showed that there were 31 dry spells and 30 wet spells in the past 1100 years, of which 1540～1590 A.D. was the longest dry period, lasting 6o years, and 1240～1270 A.D. and 1860～1890 A.D. were the longest wet periods, lasting 40 years respectively. There were 17 durations of dry period over 10 years, and 12 durations of wet period over 10 years. With regard to the century time scale, the 16th Century was 100 years of drought, with 80 years being lack of rain. The 13th Century, as well as the 19th Century, was 100 years of wet, with 60 years in spate. At the same time, another characteristic of precipitation variation in these mountains is more abrupt change. There have had 35 abrupt changes since 904 A.D., about 30 years on the average. There were 16 shifts from drought to wet, and 19 shifts from wet to drought. There were 9 abrupt changes in the 11th Century, 2 abrupt changes in the 15th and 16th Centuries. In the 20th Century there were 3 abrupt changes. Precipitation in these mountains frequently changed in the 11th Century, and less changed in the 15th and 16th Centuries. In the 20th Century precipitation changed frequently.

Key words: tree-ring, precipitation, drought and flood, Qilian Mountains