关键词: 年轮指数, 气候响应, 温度, 降水, 青藏高原

Abstract: Based on the population life table and the theory of survival analysis, and by using the age class structure represented by DBH (diameter at breast height) class and the stage-smoothing technique, a specific life table of Davidia involucrata population in Fanjing Mountain Nature Reserve was compiled, and the mortality rate curve, killing power curve, survival rate curve, and survival function curve were analyzed, aimed to reveal the quantitative dynamics of the population. There was a fluctuation in the structure of the D. involucratapopulation. The survival curve of the population appeared to be of Deevey Ⅲ type, and the individuals at young stage were abundant. The mortality rate curve and disappearance rate curve in the lifespan had similar variation trend, and the population had two distinct peaks of mortality, i.e., from Ⅰ to Ⅱ age class and from Ⅷ to Ⅸ age class. The survival analysis showed that the population mortality rate was increasing all along, while the survival rate was decreasing all the time. After Ⅷ age class, the mortality rate would exceed 92%, and the survival rate would decrease to below 8%, which indicated that hazard rate surpassed survival rate. The survival functional curve showed that the individual number of the population decreased rapidly in early age period, was stable in middle age period, and declined in old age period. The high mortality of seedlings and the deficiency of middle-age trees could be the main reasons leading to the D. involucrata population becoming endangered.

Key words: tree-ring index, climate response, temperature, precipitation, Tibetan Plateau.