黄土高原主要人工林内在水分利用效率对气象因子的响应OACHSSCD

In order to explore the physiological strategies of different plantation tree species in the face of environmental changes in the Loess Plateau,this study took Robinia pseudoacacia,Platycladus orientalis,and Populus tomentosa,which are typical plantations in Guanshan Forest Farm,Jingchuan County,Gansu Province in the Loess Plateau,as the research objects.The intrinsic water-use efficiency(iWUE)was calculated by measuring the carbon isotope value(δ13 C)of the tree rings.The response relationship between iWUE and key meteorological factors(temperature,precipitation,relative humidity and solar radiation)was analyzed to provide scientific reference for tree species selection and management of plantation in this area.The results showed that:(1)There were significant differences in tree-ring δ13 C values and iWUE among the three tree species(P＜0.01)and the size relationship is Platycladus orientalis＞Robinia pseudoacacia＞Populus tomentosa.(2)The response of iWUE of the three tree species to meteorological factors showed interspecific differences and hysteresis effects:multiple regression analysis showed that Robinia pseudoacacia was mainly positively correlated with the relative humidity in July of the current year(P＜0.01),Platycladus orientalis was mainly affected by the precipitation in June of the previous year and the minimum temperature in July of the current year(P＜0.05).The response of Populus tomentosa was more complex,which was positively affected by the relative humidity in June of the current year and the solar radiation in August of the previous year,and was significantly negatively correlated with the monthly average temperature in December of the previous year(P＜0.05).(3)Both Robinia pseudoacacia and Populus tomentosa exhibit direct influences of solar radiation and mean annual precipitation on their iWUE;however,the specific effects differ.The iWUE of Robinia pseudoacacia is positively and highly significantly influenced by solar radiation and annual precipitation,whereas that of Populus tomentosa is significantly negatively affected.In contrast,the iWUE of Platycladus orientalis is only positively and significantly influenced by solar radiation.Additionally,the iWUE of Populus tomentosa is regulated through an indirect pathway involving the mean annual minimum temperature and relative humidity.This study revealed that Platycladus orientalis had higher iWUE,followed by Robinia pseudoacacia which had higher water-use economy in the Loess Plateau.The adaptation mechanisms of different plantation tree species to climate change were multi-dimensional and cross-temporal,and different tree species had different response patterns to the same meteorological factors due to their own stomatal regulation mechanisms and growth strategies.