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Nitrogen(N)deposition is pojected to rapidly increase particularly in East Asia.Leaf δ15N has been suggested to a strong indicator of ecosystem N status(δ15N increases as ecosystem N saturation progresses),thus can provide insights into how N deposition changes ecosystem N cycling.However,how δ15N of leaf and soil in grassland ecosystems changes under elevated N inputs is less well understood.We used N addition experiments to achieve N-enriched conditions in three dominant(Agropyron cristatum.Artemisia frigida and Stipa krylovii)and other four common species(Cleistogenes squarrosa,Potentilla bifurca,Potentilla tanacetifolia and Melilotoides ruthenica)in a temperate steppe of northem China.Our objectives were to(i)assess changes in leaf 85N during 4-and 8-yr N addtions(in 2008 and 2012)in a temperate steppe and(ii)relate these changes to plant N uptake preferences and soil-N-cycling processes like denitrification and NH3 volatilization.Eight years of N addition significantly increased 85N in leaf and soil but not soil total N.Both leaf N concentration and soil inorganic N enhanced with N addition.Leaf δ15N in control plots showed small variation between sampling years,ranging from-0.30‰ in 2008 to-1.04 ‰ in 2012.However,the effects of N addition on leaf δ15N varied with treatment duration and with species.Four years of N addition significantly increased leaf δ15N of A.frigida,one dominant species.After 8 years of N added,the effect of N addition became more pronounced.Increases in leaf δ15N were apparent for five of the seven species,compared to the control.Leaf δ15N of M.ruthenica,a legume,decreased with 4-and 8-yr N addtions.Variable leaf δ5N responses among species suggest that different species may utilize different N sources.which will be further examined after measurement of δ15N for soil available N.The increases in δ15N for most species and soil N indicate that grassland ecosystem N will progress toward to N saturation with elevated N deposition in northern China.