Tree-ring Stable Carbon And Nitrogen Isotopic Composition Of Pinus Massoniana In Changting County, Fujian Province

In order to reveal the grow law and influencing factors of Masson pines(Pinus massoniana)at the background of increasing atmospheric CO2concentration and nitrogen deposition which are the main planting tree species growing serious soil erosion area as well as in order to provide theoretical basis and technical guidance for systematic management of reconstructing forest-vegetation ecosystem in Changting County,we collected the tree cores of22P. massoniana in east,west,south and north directions,which are managed in different methods of fertilization in the stage of young and unfertilization in erosion area of Hetian Town,Changting County,Fujian Province.We analysed the tree cores combined with meteorological data through cross-dating, measuring the early and late width of tree-rings in different directions,measuring stable carbon isotopic composition(δ13C) and stable nitrogen isotopic composition(δ15N),calculating the basal area increment(BAI) and water use efficiency(WUE),then we can draw the following conclusions:1. Fertilization in the stage of young increased BAI of P. massoniana significantly (p<0.01),as well as changed the sensitivity of growth to different climatic factors.We can see that BAI of P. massoniana be fertilizated correlated significantly with the relative humidity of May and September and the rainfall in September(p<0.05).BAI of P. massoniana unfertilizated correlated significantly with the temperature and relative humidity of growing season(p≤<0.05).2. WUE in P. massoniana fertilizated in the stage of young were higher significantly than those unfertilizated(p≤0.01).WUE in P. massoniana in the two different plots both showed upward trends and were more consistent with the reaction to climate factors. There were significant correlations between WUE and temperature, relative humidity, atmospheric CO2concentrations of growing season(p≤0.01).3. The source of available nitrogen at the growth process of P. massoniana is different because of the different managing methods. Nitrogen deposition and the increasing atmospheric CO2concentration increased the growth of P. massoniana after the year of2008.