Larix Gmelini Tree-ring Width Index With Responses To Climate Change In The West Of Sichuan Subalpine Zone

At present, the global climate is gradually warming, more and more attention have been paid to climatology studies by researchers from all walks of life. Dendroclimatology, the emerging discipline of a climate change research, is playing a more and more important role in climate research. Recently, a growing number of dendroclimatology scientific research have been carried out in the southwestern China, achievements in research on tree radial growth and local climate relationship becomes realizable, and the data of tree radial growth become indispensable for the study of local climate change, for the establishment of local climate sequence provides a strong basis.In this paper, Larix gmelinii, a representative species of coniferous tree species in the southwest of China, served as experimental object, adopted traditional dendroclimatological research method, and cross dating method was used to deal with the trend of the annual growth ring. The Lixian county Bipengou climate and Larix gmelinii tree ring index standard chronology (RES) have been established in this research, on the basis of the comparison of growth ring index and the local climate change curve and analysis of the correlation, the climatic factors influencing the radial growth of trees are discussed. The main results were as follows:(1) Established Larix gmelinii tree ring chronology standardized index successfully, which can be used to study climate science; ring chronology ring index sequence of different climatic factors exhibit different sensitivities.(2) According to the local meteorological data from 1971 to 2010 years of Lixian county, the annual average temperature trended upward state, the 40 years of average annual rainfall fluctuations in a certain range, however, it can be found that the slow upward trend after fitting a straight line; within 40 years, average annual precipitation and annual average temperature and local Larix gmelinii radial growth trend showed a separate phenomenon that climatic information contained in the tree ring index series in this complex relationship, and not in a climatic factor in the radial direction of the Larix gmelinii growth effect played a key role.(3) The correlation between the annual growth ring index and the average air temperature and the mean minimum air temperature in spring March was significantly correlated, and the correlation coefficient was 0.346 and 0.301 (p<0.05). The local highest temperature in June of the correlation coefficient for-0.380 (P< 0.05) reached significant correlation; correlation of Larix gmelinii and radial growth of the local monthly average precipitation was not significant (P> 0.05); via cluster analysis Larix gmelinii growing season in June and July rainfall of Larix gmelinii radial growth played a certain role in promoting.(4) The correlation coefficient of Larix gmelinii radial growth with the average precipitation in February and March was -0.331, showed significant negative correlation (p=0.039<0.05); the correlation coefficient of tree ring index and the January average temperature valued +0.304, showed significant correlation (p=0.044<0.05); meanwhile, the correlation coefficient of the average maximum temperature in June and July showed significant correlation (p=0.036<0.05) with-0.294.(5) During December of last year to February of that year, snowfall as the main source of rain, according to total precipitation amount of last year December to the year 2 months and Larix gmelinii tree ring index correlation analysis, showed that year winter snow and Larix gmelinii tree ring index series showed significant positive correlation (r=0.0426<0.05), it showed that the snow cover in winter played a role in promoting the radial growth of the local Larix gmelinii.(6) The response surface function model of annual growth ring index and precipitation, temperature is: Y=0.932-0.111P+0.121T2+0.139P~2+0.100r~*P-0.91P~2+0.46T2~*P+0.162T~*P~2 (R=0.657,R~2=0.431, F=5.219, p<0.01)(7) Almost all of the climate changes factors affecte the radial growth of Larix gmelinii, most is mainly affected by the influence of precipitation and air temperature in Larix gmelinii growing season (May to October), promotion or inhibition of Larix gmelinii of metabolism and other physiological activities took place with the precipitation and temperature in different degree, thus affected the Larix gmelinii radial growth change, in brief, growth season temperatures and precipitation had the most important role in radial growth of Larix gmelinii.(8) The acquisition of Larix gmelinii ring specimens were analyzed, and the reconstruction of growth in the early part of the season in March month average temperature and minimum temperature was executed, because the ring sequence has been through standard and detrended treatment. Furthermore, there was significant correlation between the annual growth ring index and the average temperature and the minimum temperature in the year March, regression analysis was conducted through the SPSS 20, the equation for the reconstruction was obtained as 1=-18.931+4.6811nX (R~2=0.643, F=66.553, p<0.01), and according to the error reduction formula of impairment of the equation for the reconstruction of the test, it is concluded that the test results RE=0.356>0.3, the equation described the reconstruction had high credibility, illustrated the reconstruction was successful.