Response And Prediction Of Radial Growth Of Larix Gmelinii To Climate Based On VS Model

Climate warming and its impact on the ecological environment are the core issues and important content of widespread global concern.Climate change has an impact on forest ecosystems,thereby changing their structure,function,carbon sink,and stability.The Great Xing’an Mountains is one of the regions with the most significant warming and the most sensitive to climate change in China.Rapid warming significantly affects the forest ecological environment in the Northeast Great Xing’an Mountains region.Currently,research in this region generally uses a near linear relationship to describe the response relationship between tree radial growth and the dominant climate factors.However,the response of tree growth to climate factors is not a simple near linear relationship,and it is not possible to fully understand the process of tree radial growth when only considering the impact of a single climate factor.Therefore,it is necessary to study the response relationship between tree growth and climate factors from a physiological perspective.Based on the standard tree ring width chronology of Larix gmelinii at different latitudes and meteorological station data,this paper comprehensively analyzes the response relationship and differences of radial growth of Larix gmelinii at different latitudes to climate factors in the Greater Xing’an Mountains region using correlation analysis,spatial correlation analysis,sliding correlation analysis,and VS model.In addition,the study will also use the meteorological data output from the BCC-CSM2-MR global climate model at four sampling points in the Greater Khingan Mountains region from 2021 to 2100 to predict the changes in the radial growth phenology and the radial growth status of Larix gmelinii trees.The following conclusions are obtained:(1)The characteristic parameter values of all the standard chronologies established in this article have reached a credible level,and the quality of the chronology is good.The main climatic factors affecting the radial growth of Larix gmelinii at the four sampling sites are different.The radial growth of Larix gmelinii in Huzhong and Xinlin is affected by the synergy of temperature and precipitation,while the main control factor for the radial growth of Larix gmelinii in Tahe and Songling is temperature.The higher latitudes of Tahe and Huzhong larch are more significantly regulated by the climate conditions of the previous year,and the growth of Tahe larch is inhibited by the temperature of the previous growth season;The growth of Larix gmelinii in Huzhong was inhibited by the temperature of last autumn,while precipitation had a promoting effect on it.Temperature and precipitation in the growing season of the year have a strong restrictive effect on Larix gmelinii in the Greater Khingan Mountains.Drought stress caused by high temperature in summer affects tree growth.Except for Tahe,there is a significant negative correlation between Larix gmelinii and the average maximum temperature in October of the year at other sampling points.(2)In the study area,there was a significant warming trend during 1980-1990,and the response relationship of larch to climate factors at various sampling points changed to varying degrees.The growth of Tahe larch was significantly inhibited by the temperature in July of the previous year,and its sensitivity to the precipitation in October and August of the previous year and the temperature in May of the current year was enhanced;The correlation between Huzhong larch and the precipitation in October of the previous year is relatively stable,while the correlation between the average temperature in May of the previous year,the average minimum temperature in July of the current year,and the precipitation and the average maximum temperature in October of the current year is weakened,while the correlation between the precipitation and the average maximum temperature in June of the current year is strengthened;The sensitivity of newly planted larch to the precipitation in October of last year has increased,and the correlation between the precipitation and the average maximum temperature in October of that year is relatively stable.During rapid warming,the inhibitory effect of the precipitation in December of last year on larch has increased;During the period 1980-1990,Larix gmelinii was more sensitive to the average maximum temperature in April and June of that year and the precipitation in May of that year.(3)The simulated series output from the model and the measured tree ring width standard chronology at each sampling point have a good degree of fit.The results of the initial and final growth data output from the model show that the higher the annual average temperature,the longer the growth period of larch.The daily average of growth start at each sampling point has a significant negative correlation with the temperature in April and May,while the daily average of growth end has a very significant positive correlation with the temperature in September,indicating that an increase in temperature at the beginning of the growth season is conducive to the early end of the dormancy state of larch and the start of radial growth,while higher temperatures at the end of growth will delay the arrival of the growth end date of larch,thereby extending the tree growth season.Comparing the tree growth rates induced by temperature and soil moisture in characteristic wide and narrow years,it was found that soil moisture during the growing season was the main limiting factor affecting the formation of wide and narrow rings in trees.(4)Simulating the growth trend and phenological period of Larix gmelinii in the next hundred years,the growth start date of Larix gmelinii showed an early trend,the growth end date showed a delayed trend,and the entire growth season showed an extended trend.The period 2020-2100 is divided into two periods for comparison.The tree ring width index in the later period decreases by 2.5%,12.6%,7%,and 0.3% on average compared to the previous period.The overall decline trend of Larix gmelinii in the future climate warming conditions is expected.