Response Of Radial Growth And Water Use Efficiency Of Pinus Tabulaeformis Plantation Forest To Climate Change

In order to explore the radial growth of Pinus tabulaeformis and the response of water use efficiency to climate change,Pinus tabulaeformis plantations near the precipitation line of 400-600 mm were selected.The forest sites collected 34,26,53,67-and48-year-old pine tree cores in five forest sites in Fujia,Heishui,Jiufeng,Lingkong mountain and Caijiachuan.A standardized chronology of the annual ring width at different growth stages and different ages of Pinus tabulaeformis was established,and the interannual variation of biomass and productivity of Pinus tabulaeformis were discussed.WUE calculation by stable carbon isotope method.Moreover,the relationship between water use efficiency of trees and climatic factors was examined to accurately predict the growth and the distribution changes and provide important reference for the protection and management of Pinus tabulaeformis plantation.The main research conclusions are as follows:?1?The average sensitivity value and standard deviation of Pinus tabulaeformis in its juvenile stage were higher than those in its mature stage.The response of tree growth to environmental change decreased with the increase of tree age.?2?The response of Pinus tabulaeformis radial growth to climate change was different with growth and development.Temperature was the main climatic factor limiting the radial growth of Pinus tabulaeformis in Fujia and Heishui.As Pinus tabulaeformis grows,the sensitivity of radial growth to climate change increased.Precipitation promoted the growth of Pinus tabulaeformis in young age of Jiufeng Forest Farm.The correlation coefficient between the radial and precipitation of Pinus tabulaeformis in Lingkong Mountain which in the late growth period was both larger than that in the young and middle ages,reached0.7,and the rainfall in the late growth period was the main climatic factor that limited the radial growth of Pinus tabulaeformis in Lingkong Mountain.?3?The increase in useful chest height break and cross-sectional area BAI at different sites had a greater response to temperature than to precipitation,and temperature promotes BAI at young age.The order of BAI of Pinus tabulaeformis in its juvenile stage was Jiufeng>Fujia>Lingkong Mountain>Cai Jiachuan>Heishui.?4?The biomass per plant of Pinus tabulaeformis in five different samples showed an increasing trend year by year.Among them,the annual growth rate of biomass of single plant on the site and underground of Lingkong mountain forest was the largest,which were0.282 kg·a^-1and 0.129 kg·a^-1respectively.?5?There were some differences in WUE of Pinus tabulaeformis in different sites,but all showed a significant upward trend over time.The WUE of Pinus tabulaeformis increased with the age of the forest.The order of WUE rising rate was Heishui>Fujia>Caijiachuan>Lingkong Mountain.WUE is mostly negatively correlated with precipitation and drought index,but positively correlated with temperature.Temperature was the main climatic factor affecting WUE of Pinus tabulaeformis.There was a significant positive correlation between water use efficiency of Pinus tabulaeformis and biomass.