Dendroclimatic Response of Emergent Old?growth Cypress and Fir Natural Forest in Northeastern Taiwan

The purpose of this study was to apply the dendroclimatology method on the analysis of the climatic and disturbance factors of Chilan alpine area on the tree rings of red cypress, yellow cypress, Taiwania, and Lunta fir in North Taiwan in order to establish a standardization chronology. The analysis ring width, along with the monthly mean temperature, monthly precipitation, and monthly radiation by applied correlation function and response function from 1936 to 2003 showed that there were positive correlation between the ring width indices of the 4 species and the monthly mean temperature of previous November and December, current January and March, and the monthly precipitation of the previous July, However, there was a negative correlation between the ring width indices with the previous monthly mean temperature of the previous July and the monthly precipitation of the previous September. Further, there was a positive correlation between the ring widths and the monthly radiation of March of the current year and a negative correlation between the ring widths and monthly radiation of the previous July. Thus, the ring widths chronology of 4 species were influenced by the monthly mean temperature of current March and the monthly precipitation of the previous July. Base on the standardization chronology, the analysis results showed that there is negative correlation between the ring width indices and the maximum wind speed within 10 minutes of the previous September and June of the current year and July (from 1950 thru 2003), if typhoons occurred in those months. The results also showed that the ring widths indices of the 4 species were not only influenced by climatic factors, but also by the disturbance of typhoons. This shows that typhoon frequency and disturbances are valuable in the reconstruction of a past climate