| Summary: | 碩士 === 國立東華大學 === 應用數學研究所 === 85 ===
This research documents two 53-year time series (1940-1992) record of tree rings δ13C of Taiwan fir (Abies Kawakamii (Hayata) Ito) from southern Taiwan. The growth rate of the fir were inclined to increase, but changed slightly after that. Such a long-term variability can be attributed to a combination of the juvenile effect during the early stage of tree growth and alater addition of photosynthetically fixed light carbon from fossil fuel combustion and biospheric CO2 release. Results indicates that the growth of the Taiwan fir stabilizes after the juvenile effect, and the correlations between 5" c in the tree-rings and precipitation or temperature were not influenced by the growth. The s"c-will show correlations with precipitation or temperature when the tree reaches stable growth. Therefore, based upon the presumed relationship, the s"c time series records will be use after 1940A.D..
Portion of the δ13C time series records (1940-1992) is further used to test their potential correlations to the mean annual precipitation and temperature data using the Scientific Computing Associates (SCA) statistical system. Several transfer function models were established, in which the δ13C series could be decomposed into three components: a deterministic non-linear trend, an independent precipitation or temperature term, and a disturbance or white noise term. Multiple correlation coefficients reveal that the δ13C trend is correlated fairly well to the mean annual precipitation and temperature records. Furthermore, in order to test the potential use of δ13C trend to infer the past changes in precipitation or temperature, the modeled equations are detrended to "model-adjusted δ13C" indices in this study. By correlating these indices to the known climatic records, the changes of precipitation and temperature in the past are able to be infered. The adequacy of all these models is justified after regular diagnostic checking and is further confirmed with excellent forecasts and/or backforecasts. The study thus not only provides a method for correlating tree ring δ13C time series to the mean annual precipitation or temperature trend, but also shows the feasibility of using tree ring δ13C series for infering the past precipitation and temperature changesas well.
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