A 2122-year tree-ring chronology of Douglas-fir and spring precipitation reconstruction at Heal Lake, southern Vancouver Island, British Columbia
Date
1996
Authors
Zhang, Qibin
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Abstract
A 2122-year tree-ring chronology was developed from living and submerged logs of Douglas-fir at Heal Lake, near Victoria, southern Vancouver Island, British Columbia. Correlations between the tree-ring indices and monthly mean temperature and monthly total precipitation indicated that the radial growth of Douglas-fir was strongly correlated with the spring and early summer (April-July) precipitation and the previous years' growth.
A transfer function was established using tree-ring indices to predict the weighted 5 years' effective precipitation. The reconstructed precipitation history for the last two millennia exhibited eight distinct climatic intervals involving long periods of wetness and drought and extreme events. The result showed that the Little Ice Age was featured by wetness in the interval AD. 1567-1765 and there were occurrences of wet episodes before and after this interval. There was no evidence of Medieval Warm Period in the area. Comparison with other studies in the nearby regions showed general agreement and demonstrated a regional climatic control. The result can be applied in a broad range from the fundamental understanding of the climate system to the practical management of our natural resources.