Radial Growth,Net Primary Productivity And Intrinsic Water Use Efficiency Of Robinia Pseudoacaciar Response To Climatic Factors

The tree-ring width chronologies of all wood（RW）,Earlywood（EW）and Latewood（Latewood）of Robinia pseudoacacia in the study area were established by dendrochronology.The Basal area increment（BAI）and Net primary productivity（NPP）data of Robinia pseudoacacia in the study area were obtained based on the wheel width data,and the inter-annual Intrinsic water use efficiency（WUE_i）of Robinia pseudoacacia was calculated by measuring the tree-ringδ¹³C values.Combined with historical meteorological data,the differences of radial growth,NPP and WUE_i of Robinia pseudoacacia in different locations and their responses to climate factors were analyzed,aiming to provide reference for rational management of Robinia pseudoacacia plantation.The main conclusions of this paper are as follows:（1）The BAI change trends of Robinia pseudoacacia in different locations were similar,RW and LW both showed a quadratic curve,and EW both showed a linear upward trend.On a monthly scale,the radial growth of Robinia pseudoacacia in Minquan and Jiyuan is significantly positively correlated with the average precipitation,relative humidity and SPEI during the growing season,and negatively correlated with the average temperature,maximum temperature and minimum temperature.The opposite is true in Yichuan and Baishui.The radial growth of Robinia pseudoacacia in Dongying The correlation with climate factors is poor.On the annual scale,the annual average temperature is the dominant factor affecting the radial growth of EW,LW and RW of Robinia pseudoacacia in the study area.In addition,the average annual precipitation is also an important climatic factor affecting the growth of EW.（2）The variation trend of Robinia pseudoacacia forest biomass and NPP was different in different regions.Except for t Minquan,the other four regions showed a significant upward trend.On the monthly scale,except for Minquan,the biomass and NPP of Robinia pseudoacacia forest in the other four sites showed a significant upward trend.On the monthly scale,the NPP of Robinia pseudoacacia in Dongying and Baishui was significantly negatively correlated with the mean precipitation,relative humidity and SPEI in spring,while Minquan was significantly negatively correlated with the mean temperature,maximum temperature and minimum temperature in spring and summer.The significance of Jiyuan and Yichuan was poor.At the annual scale,the NPP of Robinia pseudoacacia was mainly regulated by annual mean temperature,annual maximum temperature and annual minimum temperature.（3）WUE_i of Robinia pseudoacacia,RW,EW and LW showed a linear upward trend in different regions,and only the interannual growth rates of WUE_i were different.On the monthly scale,except for Yichuan,the average monthly rainfall was positively correlated with other regions in most months,but the significance was poor.It was significantly positively correlated with the average monthly temperature,the maximum monthly temperature and the minimum monthly temperature in the growing season.Except for Jiyuan and Yichuan,monthly relative humidity and monthly SPEI were significantly negatively correlated with spring WUE_i of Robinia pseudoacacia.On the annual scale,the effects of annual mean temperature,annual minimum temperature and annual maximum temperature on WUE_i were strong,and the effects of annual mean rainfall,annual SPEI and annual relative humidity on WUE_i were relatively weak.