Respone Of Pinus Massoniana And Pinus Tabulaeformis Tree Growth To Climate Factors In Jigong Mountain

Global climate change has a great impact on human society and ecosystem.Jigong Mountain is located in the west of Dabie Mountains,in the transition zone of warm temperate zone and north subtropical zone,it is sensitive to climate change.It is also the north boundary of Pinus massoniana growth and the south boundary of Pinus tabulaeformis growth,and the tree growth is very sensitive to climate change.Therefore,it is of great significance to carry out the tree ring climate research on the chronology of Pinus massoniana and Pinus tabulaeformis in Jigong Mountain area.Based on the principles and methods of tree ring theory,samples were taken from Jigong Mountain(JGS)and Bolden(BED)of Jigongshan National Nature Reserve,and six standard tree chronologies for tree ring widths in different habitats were established(Pinus massoniana: BED02,BED0607,JGS02 and JGS03;Pinus tabulaeformis: BED01 and JGS01).The regional PC1 chronology of P.massoniana,the average chronology of P.tabulaeformis region and the regional PC1 chronology of Jigong Mountain based on the standard chronology of six sampling points were synthesized.The correlation analysis of all chronologies with the monthly average minimum temperature,monthly average temperature,monthly average maximum temperature,monthly precipitation and monthly average relative humidity of Xinyang and Macheng from 1978 to 2018,which are close to the sampling points,was carried out to determine the main limiting factors of tree growth.In order to further understand the impact of climate change on the forest system,and provide scientific basis for forest management in this area.Through the tree-ring climate response analysis of the related chronology of Masson pine,it was found that the radial growth of Masson pine in the Jigong Mountain area was more sensitive to the temperature and humidity of May-July in the Macheng Meteorological Station.The possible reason for the decrease in the growth rate of Masson pine from 1998 to 2012 was that the temperature from May to July in 1998-2012 was higher than the multi-year average,which was in a warmer period,and the chronology was significantly negatively correlated with the temperature data from May to July,thereby inhibiting the radial growth of Masson pine.The correlation analysis results of the regional PC1 chronology and climate factors in the Jigong Mountain area show that the average minimum temperature of Xinyang Meteorological Station from August to October of that year was the main climatic factor affecting the radial growth of trees in the Jigong Mountain area.Based on this,the tree diameter was established.To the growth-climate factor equation,and found that there was a certain difference between the response of P.massoniana and P.tabulaeformis to temperature: the growth of P.tabulaeformis and the low-temperature changes from August to October were well-matched and synchronized,while the growth of Masson pine Although it shows a high similarity to the low-temperature change from August to October,the high-frequency fluctuations are larger,and it seems to be more sensitive to the low temperature from August to October.The tree-ring climatological study in the Jigong Mountain area reveals the effect of temperature on the radial growth of trees.Studying the response relationship between climate change and tree growth can provide some basic data for forest management,and also has a certain reference value for the study of other species.