Climatic Factors on Growth of Pinus latteri Mason in Hill Evergreen Forest at Phu Kradueng National Park, Loei Province

Abstract

This study focused on the growth of Pinus latteri and its relationship to climatic data in order to reconstruct the climate in the past. Following the dendrochronological techniques, the growth pattern of 38 core samples from 19 trees was found to be similar to an average critical level of correlation higher than 0.3281. The oldest sample was found to have 129 annual rings, formed between 2431 to 2559 B.E. The annual increment in radius of Pinus latteri could be explained by using an exponential growth pattern, which had an average tree - ring width of 0.358 cm. The correlation analysis between tree - ring index and climatic data indicated that the monthly average minimum temperature in October and the monthly average relative humidity in March, October and November were significantly correlated (p<0.05) to the tree-ring index. It was also found that the monthly average relative humidity in February of the previous year had significant correlation
(p<0.01) with the tree - ring index as well as the monthly average maximum temperature and the monthly average relative humidity in March of the previous year. The past climate reconstructed from relative humidity in February of the previous year data showed that for the last 62 years, the average monthly relative humidity in Thailand during the month of February has increased by 1 percent since 2431 B.E. with a tendency to continuously increase in the future.