Response Of Radial Growth Of Subalpine Coniferous Forest To Climate In Daofu County,Sichuan Province

The western Sichuan Plateau is located on the eastern edge of the Qinghai-Tibet Plateau.Its unique geographical environment and climatic conditions have grown the vegetation types,and it is one of the most widely distributed areas of coniferous forests in China.At the same time,the region is also one of the most sensitive regions of climate change in China,and it is an ideal region to study the response of coniferous forest growth to climate change.In recent decades,the temperature in the western Sichuan Plateau has shown a rapid upward trend,which may affect the growth of coniferous forests.This paper takes Daofu County coniferous forest as the research object,and uses the tree-wheel ecology method to sample and analyze the main coniferous species such as Picea likiangensis,Sabina saltuaria and Larix potaninii.And to explore the response characteristics of radial growth of different conifer species to climate change.By sampling and analyzing Picea likiangensis along the elevation gradient,the mechanism of the influence of altitude on the sensitivity of coniferous forest to climate change was revealed.The main results are as follows:(1)Since the 1980 s,Daofu County has experienced significant periods of warming.The annual average temperature,the lowest temperature and the highest temperature all show a clear upward trend.There is no obvious change in precipitation.(2)There are significant differences in the response of different conifer species to climate change at similar altitudes.The radial direction of Picea likiangensis and Sabina saltuaria is mainly affected by the temperature of autumn and winter in the previous year,and the correlation is significant,and it is negatively correlated with winter precipitation and early summer PDSI.This indicates that winter precipitation and PDSI were not conducive to the radial growth of Picea likiangensis.There is no obvious correlation between Sabina saltuaria and precipitation.The redwood(Larix potaninii)is positively correlated with the temperature of the summer,indicating that the summer temperature rise is conducive to the radial growth of the redwood.The red cedar(Larix potaninii)is most sensitive to climate change.(3)The chronological statistical characteristics of Picea likiangensis at different altitudes showed significant changes in the elevation gradient,and there were also gradient differences in response to climate change.The plots of low altitude,medium altitude and high altitude were significantly negatively correlated with the temperature of autumn and winter in the previous year,and positively correlated with the spring and summer of the year,but the correlation was weak.The low temperature in winter limits the radial growth of the western spruce.The response relationship between the altitude plots and the precipitation factors is consistent with the temperature factor,which is negatively correlated with the winter and summer seasons and positively correlated with the spring and autumn seasons.The climate is dry in spring and autumn,and suitable moisture is conducive to radial growth.The plots at various altitudes were weakly negatively correlated with relative humidity factors and PDSI factors.The main effect on the radial growth of Picea likiangensis is the temperature factor and precipitation factor of the previous year.