Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under ...Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under future global climate change. In this study, the ecophysiological parameters of saplings and trees of Fraxinus mandshurica Rupr. were measured at different levels of nitrogen addition in a temperate forest. The results show that ecophysiological parameters maximum net photosynthetic rate(Pmax), apparent quantum efficiency(a), dark respiration(Rd), light saturation point(Lsp), photosynthetic nitrogen use efficiency(PNUE),specific leaf area(SLA)and stomatal conductance under saturated light intensity(Gsmax) were higher in saplings than in trees. These physiological parameters and not Nleaf(leaf nitrogen content)led to relatively lower Pmaxand Rdin trees. For both saplings and trees, low and median nitrogen addition(23 and 46 kg ha-1a-1) resulted in significant increases in Pmax, Rd, Lsp, Chl, PNUE, SLA and Gsmax. These parameters tended to decline under high additions of nitrogen(69 kg ha-1a-1),whereas Nleaf was always enhanced with increasing nitrogen. Variations in Pmax and Rd with increasing nitrogen were attributed to variations in the strongly related parameters of, Lsp, Chl, PNUE, SLA and Gsmax. Overall, the response sensitivity of physiological parameters to enhanced nitrogen levels was lower in trees compared with saplings.展开更多
基金funded by the National Key Research and Development Program of China(2016YFC0400206-04,2017YFC0505304)the National Natural Science Foundation of China(51309016)+1 种基金Central Public-interest Scientific Institution Basal Research Fund(CKSF2016007/TB)Changjiang River Scientific Research Institute Innovation Team(CKSF2017064/NS)
文摘Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under future global climate change. In this study, the ecophysiological parameters of saplings and trees of Fraxinus mandshurica Rupr. were measured at different levels of nitrogen addition in a temperate forest. The results show that ecophysiological parameters maximum net photosynthetic rate(Pmax), apparent quantum efficiency(a), dark respiration(Rd), light saturation point(Lsp), photosynthetic nitrogen use efficiency(PNUE),specific leaf area(SLA)and stomatal conductance under saturated light intensity(Gsmax) were higher in saplings than in trees. These physiological parameters and not Nleaf(leaf nitrogen content)led to relatively lower Pmaxand Rdin trees. For both saplings and trees, low and median nitrogen addition(23 and 46 kg ha-1a-1) resulted in significant increases in Pmax, Rd, Lsp, Chl, PNUE, SLA and Gsmax. These parameters tended to decline under high additions of nitrogen(69 kg ha-1a-1),whereas Nleaf was always enhanced with increasing nitrogen. Variations in Pmax and Rd with increasing nitrogen were attributed to variations in the strongly related parameters of, Lsp, Chl, PNUE, SLA and Gsmax. Overall, the response sensitivity of physiological parameters to enhanced nitrogen levels was lower in trees compared with saplings.
