Response Of Radial Growth And Vessel Characteristics For Quercus Mongolica And Phellodendron Amurense To Climate Change

Quercus mongolica and Phellodendron amurense are two important broad-leaved species in temperate forests of Northeast China.It is critical to explore their responses to climate change for providing management,protection and restoration of the broad-leaved forest in northeast China under the future climate change scenario.Three sampling sites along a longitude gradient—Heilun(HL),Tieli(TL)and Xilin(XL)were set up in the Xiaoxing’an Mountains.Dendrochronological methods and measuring wood anatomy methods were used to establish standard chronologies chronologies and earlywood vessel parameters chronologies for Quercus mongolica and Phellodendron amurense separately in the study area.Then,correlation analyses were conducted between these chronologies and local climatic factors to reveal the spatial and temporal variations in radial growth,vessel characteristics and climate relationship of Quercus mongolica and Phellodendron amurense.The results showed that correlation between the radial growth of Phellodendron amurense and temperature of growing season is strong,and correlation between the radial growth of Quercus mongolica and the temperature and precipitation of growing season is strong.However,temperature sensitivities of these two species were not the same.Spring temperature was negative correlation with radial growth of Quercus mongolica,and it was positive correlation with radial growth of Phellodendron amurense.High maximum temperature in June was significant negative correlation with radial growth of Quercus mongolica,but it was weak correlation with Phellodendron amurense.The correlation between earlywood vessel size of these two species and mean temperature is strong,but the correlation with precipitation was weak.Radial growth of Quercus mongolica was significant positive correlation with standardized precipitation-evapotranspiration index(SPEI)in June.In July with abundant precipitation,only radial growth of Quercus mongolica was significant positive correlation with SPEI in July,while Phellodendron amurense didn’t change significantly.Precipitation before growing season was positive correlation with earlywood vessel size of Quercus mongolica in Hailun,and it was negative correlation with earlywood vessel size of Quercus mongolica in Tieli and Xilin,but it was weak correlation with Phellodendron amurense.The physiological characteristics of the two tree species was the key factors affecting their growth-climate relationship.Along with the significant warming since the 1976,the radial growth trend of Phellodendron amurense increased,whilst the growth of Quercus mongolica decreased;The earlywood vessel size of Quercus mongolica was negative correlation turn into positive correlation with precipitation before growing season,number of earlywood vessel was positive correlation turn into negative correlation,earlywood vessel size of Phellodendron amurense was more sensitive with precipitation before growing season.Deteriorated drought stress caused by warming may be the main reasons for the different responses of the two tree species,and different responses of earlywood vessel characteristics.