Growth And Climatic Response Of Pinus Sylvestris Var.mongolica In Sandy Land Of Zhang-Gu-Tai,Liaoning Province

Pinus sylvestris var.mongolica has the functions of both production and ecology,plays an important role in economic,ecological and social benefits,and is the main tree species for afforestation of windbreak and sand fixation in the "three north" regions of China.However,In the past 20 years,the growth of Pinus sylvestris var.mongolica plantations began to decline in some areas,and its physiological characteristics were significantly affected by climate change.In this study,the growth process and growth equation of the height,DBH and volume of Pinus sylvestris var.mongolica at different ages in zhanggutai experimental base of liaoning province were analyzed by trunk analysis and dendrochronology science.Meanwhile,the local meteorological data from 1967 to 2016 were used to study the difference in the radial growth response to climate change and the ability to cope with extremely dry weather.The main research results are as follows1.The average annual temperature in zhanggutai area has been rising significantly in recent 50 years.The annual precipitation fluctuates greatly and decreases slightly on the whole.At the same time,the responses of different ages to various climatic factors were different,but the overall effect was the joint effect of precipitation and temperature.There was a positive correlation between the growth of Pinus sylvestris var.mongolica and the precipitation and the Palmer Drought Severity Index(PDSI)in the growing season,but a negative correlation between the growth and temperature,and the response of<40a to various climatic factors was more significant than that of>40a2.From the point of view of single drought and the whole drought period,the ability of Pinus sylvestris var.mongolica of different ages to cope with extreme drought was as follows:the resistance of older Pinus sylvestris var.mongolica to drought was significantly higher than that of younger Pinus sylvestris var.mongolica.However,the resilience of older Pinus sylvestris var.mongolica was lower than that of younger Pinus sylvestris var.mongolica,and the elastic ability of older Pinus sylvestris var.mongolica was higher,that is to say,the ability to recover to its original growth level was stronger than that of younger Pinus sylvestris var.mongolica.3.Through the in-depth study of the standard trees in 8 plots,it was found that the tree height,DBH and total volume growth of Pinus sylvestris var.mongolica increased with the increase of age,but did not change regularly with different ages.The Logistic growth equation fits the tree height,DBH and volume growth process of Pinus sylvestris var.mongolica well(R2>0.96).The natural growth process and stage of Pinus sylvestris var.mongolica can be obtained indirectly by growth equation,that is to say,the fitting model is more scientific.It can be applied to the actual management of Pinus sylvestris var.mongolica.4.Through the division of the growth stage of Pinus sylvestris var.mongolica,the growth growth period of Pinus sylvestris var.mongolica height is 6a-26a;Diameter at breast height:lla-36a;The timber volume entered the fast growth period late,the fast growth period time is 20a-46a.