Liu Hongbin, Wu Xiangding, Shao Xuemei
In this paper.We concentrate on the study of the possibility of the usage of tree ring Image Analysis in the climate change research during historical time in Kangding area of Sichuan Province,with Picea balfouriana sampled from West Sichuan Province.Image analysis is a new method used in dendroclimatology with the reflected brightness (defined as Gray Value) as climate change indicators.There are ten different parameters, which include three ring width series and seven gray value series.got from image analysis.Twenty samples of eleven trees are selected by correlation analysis to be used in chronologies.The research period is 1950-1992.there is almost no difference between the ring width series derived from image analysis and from ring width measurement instrument.So the series from image analysis can be used in the comimg research.The relationship between the series of gray value parameters is not as close as that of the series of ring width parameters.Ten chronologies is built.Divide the seven Gray Value chronologies into two parts:on is the Maximum Gray Value, Early Wood Gray Value and Tree Ring Gray Value; the other is Minimum Gray Value, Ratio Between Maximum and Minimum Gray Value, difference Between maximum and Minimum Gray Value and later wood gray value.Relationship between the chronologies in part is closer than that of different parts.Four monthly averaged climate factors (precipitation,temperature, maximum temperature and minimum temperature) are used in the analysis to discover the relationship between the chronologies and climate change.It is shown that changes in ring width chronologies are closer to that of yearly precipitation, and the correlation coefficient is 0.42.Changes in gray value chronologies are closer to that of monthly averaged temperature parameters.especially the relationship between the March-april maximum averaged temperature and the minimum gray value, gray value ratio, gray value difference, three ring gray value and later wood gray value.The correlation coefficients between is -0.58.-0.56.0.53, -0.51 and -0.58,respectively.So.we can see that more useful data are derived from image analysis.and more information on the climate change during the historical time will be derived from the analysis of these data.
