While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly,aerosol ammonium nitrate remains high in East China.As the high nitrate abundances are...While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly,aerosol ammonium nitrate remains high in East China.As the high nitrate abundances are strongly linked with ammonia,reducing ammonia emissions is becoming increasingly important to improve the air quality of China.Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions,long-term surface observation of ammonia concentrations are sparse.In addition,there is still no consensus on whether agricultural or non-agricultural emissions dominate the urban ammonia budget.Identifying the ammonia source by nitrogen isotope helps in designing a mitigation strategy for policymakers,but existing methods have not been well validated.Revisiting the concentration measurements and identifying source apportionment of atmospheric ammonia is thus an essential step towards reducing ammonia emissions.展开更多
Priming effect(PE)on soil organic carbon(SOC)decomposition caused by the addition of organic carbon(C)is an important ecological process in regulating soil C cycle.Additionally,most priming studies are confined to lab...Priming effect(PE)on soil organic carbon(SOC)decomposition caused by the addition of organic carbon(C)is an important ecological process in regulating soil C cycle.Additionally,most priming studies are confined to laboratory trials,while the assessment of soil PE under field conditions with variable weather conditions is scarce.This study assessed the direct effects of glucose addition and in-situ warming on the extent of PE under field conditions in a temperate forest.We evaluated soil PE using 13C-glucose labelling,a simple and novel technique,based on the Keeling plot method.Glucose addition significantly enhanced native SOC decomposition and induced strong PE.However,the effect of in-situ warming on the extent of PE was not significant.This study confirms the importance of PE in regulating SOC turnover under field conditions.展开更多
Background:Conifers partition different N forms from soil,including ammonium,nitrate,and dissolved organic N(DON),to sustain plant growth.Previous studies focused on inorganic N sources and specific amino acid forms u...Background:Conifers partition different N forms from soil,including ammonium,nitrate,and dissolved organic N(DON),to sustain plant growth.Previous studies focused on inorganic N sources and specific amino acid forms using ^(15)N labelling,but knowledge of the contribution of DON to mature conifers’N uptake is still scarce.Here,we quantified the contribution of different N forms(DON vs.NH_(4)^(+)vs.NO_(3)^(−))to total N uptake,based on ^(15)N natural abundance of plant and soil available N,in four mature conifers(Pinus koraiensis,Pinus sylvestris,Picea koraiensis,and Larix olgensis).Results:DON contributed 31%,29%,28%,and 24%to total N uptake by Larix olgensis,Picea koraiensis,Pinus koraiensis,and Pinus sylvestris,respectively,whereas nitrate contributed 42 to 52%and ammonium contributed 19 to 29%of total N uptake for these four coniferous species.Conclusions:Our results suggested that all four conifers could take up a relatively large proportion of nitrate,while DON was also an important N source for the four conifers.Given that DON was the dominant N form in study soil,such uptake pattern of conifers could be an adaptive strategy for plants to compete for the limited available N sources from soil so as to promote conifer growth and maintain species coexistence.展开更多
Background:Forest succession is an important ecological process and has been studied for more than a century.However,changes in nitrogen(N)availability during succession remain unclear as they may lead to either N sat...Background:Forest succession is an important ecological process and has been studied for more than a century.However,changes in nitrogen(N)availability during succession remain unclear as they may lead to either N satura-tion or N limitation.Here,we propose a conceptual model to illustrate changes in N availability during four stages of secondary succession using the natural abundance of ^(15) N in plant leaves(foliarδ^(15)N).We predicted that N availability would decline in the early stages of succession and then increase in late stages,coinciding with the changes in foliarδ^(15)N,with the inflection point varying in different climate zones.Data on foliarδ^(15)N from 16 succession sequences were synthesized to explore changes in N availability during forest succession.Results:The compiled data were consistent with the proposed conceptual model.Foliarδ^(15)N in boreal and temperate forests decreased significantly in the first two stages of succession(estimated to last at least 66 years in temperate forests),at a rate of 0.18‰and 0.38‰per decade,respectively,and decreased slightly in tropical forests in the first 23 years.Foliarδ^(15)N is projected to increase in later stages in all forests,which is supported by observations in both temperate and tropical forests.The inflection points of N availability when N limitation peaked during succession were different in different climate zones,implying different ecosystem N turnovers.Conclusions:Our study reconciles the controversies regarding changes in N availability during forest secondary succession.Our findings are also useful for predicting the recovery of N and carbon accumulation during succession.Nonetheless,studies on forest secondary succession using foliarδ^(15)N have thus far been limited,and more research should be conducted to further verify the conceptual model proposed here.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0210100)National Research Program for Key Issues in Air Pollution Control(Grant No.DQGG0208)+1 种基金the National Natural Science Foundation of China(Grant No.41405144)WWW acknowledges support from the Atmospheric and Geospaces Sciences U.S.National Science Foundation(Grant No.AGS 1351932)。
文摘While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly,aerosol ammonium nitrate remains high in East China.As the high nitrate abundances are strongly linked with ammonia,reducing ammonia emissions is becoming increasingly important to improve the air quality of China.Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions,long-term surface observation of ammonia concentrations are sparse.In addition,there is still no consensus on whether agricultural or non-agricultural emissions dominate the urban ammonia budget.Identifying the ammonia source by nitrogen isotope helps in designing a mitigation strategy for policymakers,but existing methods have not been well validated.Revisiting the concentration measurements and identifying source apportionment of atmospheric ammonia is thus an essential step towards reducing ammonia emissions.
基金supported by the National Natural Science Foundation of China(Nos.U22A20612 and 41877092)National Key R&D Program of China(Nos.2022YFF1303003 and 2016YFA0600802)+2 种基金K.C.Wong Education Foundation,China(No.GJTD-2018-07)Research and Development Project of Scientific Instruments and Equipment of Chinese Academy of Sciences(No.YJKYYQ20190054)Liaoning Vitalization Talents Program,China(No.XLYC1902016).
文摘Priming effect(PE)on soil organic carbon(SOC)decomposition caused by the addition of organic carbon(C)is an important ecological process in regulating soil C cycle.Additionally,most priming studies are confined to laboratory trials,while the assessment of soil PE under field conditions with variable weather conditions is scarce.This study assessed the direct effects of glucose addition and in-situ warming on the extent of PE under field conditions in a temperate forest.We evaluated soil PE using 13C-glucose labelling,a simple and novel technique,based on the Keeling plot method.Glucose addition significantly enhanced native SOC decomposition and induced strong PE.However,the effect of in-situ warming on the extent of PE was not significant.This study confirms the importance of PE in regulating SOC turnover under field conditions.
基金funded by the National Key Research and Development Program of China(2016YFA0600802)Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDB-SSW-DQC002)+4 种基金K.C.Wong Education Foundation(GJTD-2018-07)Liaoning Vitalization Talents Program(XLYC1902016)the National Natural Science Foundation of China(41773094,41811530305,31901134,41571455,and 31770498)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA23070103)Scientific Research Foundation of the Educational Department of Liaoning Province(L201908).
文摘Background:Conifers partition different N forms from soil,including ammonium,nitrate,and dissolved organic N(DON),to sustain plant growth.Previous studies focused on inorganic N sources and specific amino acid forms using ^(15)N labelling,but knowledge of the contribution of DON to mature conifers’N uptake is still scarce.Here,we quantified the contribution of different N forms(DON vs.NH_(4)^(+)vs.NO_(3)^(−))to total N uptake,based on ^(15)N natural abundance of plant and soil available N,in four mature conifers(Pinus koraiensis,Pinus sylvestris,Picea koraiensis,and Larix olgensis).Results:DON contributed 31%,29%,28%,and 24%to total N uptake by Larix olgensis,Picea koraiensis,Pinus koraiensis,and Pinus sylvestris,respectively,whereas nitrate contributed 42 to 52%and ammonium contributed 19 to 29%of total N uptake for these four coniferous species.Conclusions:Our results suggested that all four conifers could take up a relatively large proportion of nitrate,while DON was also an important N source for the four conifers.Given that DON was the dominant N form in study soil,such uptake pattern of conifers could be an adaptive strategy for plants to compete for the limited available N sources from soil so as to promote conifer growth and maintain species coexistence.
基金supported by National Key Research and Development Program of China(No.2016YFA0600802)K.C.Wong Education Foundation(GJTD-2018–07)+1 种基金Liaoning Vitalization Talents Program(XLYC1902016)the National Natural Science Foundation of China(41773094,31901134)。
文摘Background:Forest succession is an important ecological process and has been studied for more than a century.However,changes in nitrogen(N)availability during succession remain unclear as they may lead to either N satura-tion or N limitation.Here,we propose a conceptual model to illustrate changes in N availability during four stages of secondary succession using the natural abundance of ^(15) N in plant leaves(foliarδ^(15)N).We predicted that N availability would decline in the early stages of succession and then increase in late stages,coinciding with the changes in foliarδ^(15)N,with the inflection point varying in different climate zones.Data on foliarδ^(15)N from 16 succession sequences were synthesized to explore changes in N availability during forest succession.Results:The compiled data were consistent with the proposed conceptual model.Foliarδ^(15)N in boreal and temperate forests decreased significantly in the first two stages of succession(estimated to last at least 66 years in temperate forests),at a rate of 0.18‰and 0.38‰per decade,respectively,and decreased slightly in tropical forests in the first 23 years.Foliarδ^(15)N is projected to increase in later stages in all forests,which is supported by observations in both temperate and tropical forests.The inflection points of N availability when N limitation peaked during succession were different in different climate zones,implying different ecosystem N turnovers.Conclusions:Our study reconciles the controversies regarding changes in N availability during forest secondary succession.Our findings are also useful for predicting the recovery of N and carbon accumulation during succession.Nonetheless,studies on forest secondary succession using foliarδ^(15)N have thus far been limited,and more research should be conducted to further verify the conceptual model proposed here.
