Aims Given the importance of resorption in nutrient conservations,nu-trient resorption should change with leaf age if resorption depends on nutrient content,and if nutrient content changes with leaf age.However,no stu...Aims Given the importance of resorption in nutrient conservations,nu-trient resorption should change with leaf age if resorption depends on nutrient content,and if nutrient content changes with leaf age.However,no study has addressed this issue.Methods Here,we measured N and P concentrations of needles of different ages in two woody evergreen conifer species-white spruce(Picea glauca Voss.)and balsam fir(Abies balsamea Mill.)-to determine the effects of needle aging on nutrient resorption.Important Findings For both species,N and P concentrations were higher in newer needles than in older needles.Nutrient resorption efficiency,i.e.percentage of nutrients resorbed during senescence,also declined significantly with needle age from 73 to 22%in these two evergreen conifer species.The difference in nutrient resorp-tion between old and young needles may be attributed to the size of N and P sink tissues,which is likely to decrease with needle age.These results suggest that needle age affects the extent of N and P resorption in these two evergreen conifer species.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(2016YFA0600801)the National Natural Science Foundation of China(31370455 and 31570438)+1 种基金One Hundred Person Project of Shaanxi Province(A28902170)Special Foundation of the State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau(A314021403-C9).
文摘Aims Given the importance of resorption in nutrient conservations,nu-trient resorption should change with leaf age if resorption depends on nutrient content,and if nutrient content changes with leaf age.However,no study has addressed this issue.Methods Here,we measured N and P concentrations of needles of different ages in two woody evergreen conifer species-white spruce(Picea glauca Voss.)and balsam fir(Abies balsamea Mill.)-to determine the effects of needle aging on nutrient resorption.Important Findings For both species,N and P concentrations were higher in newer needles than in older needles.Nutrient resorption efficiency,i.e.percentage of nutrients resorbed during senescence,also declined significantly with needle age from 73 to 22%in these two evergreen conifer species.The difference in nutrient resorp-tion between old and young needles may be attributed to the size of N and P sink tissues,which is likely to decrease with needle age.These results suggest that needle age affects the extent of N and P resorption in these two evergreen conifer species.
