Aims Long-term nitrogen(N)fertilization has profound impacts on com-munity structure and ecosystem function,but little is known about its effects on plant phenology.Furthermore,no published study has examined effects ...Aims Long-term nitrogen(N)fertilization has profound impacts on com-munity structure and ecosystem function,but little is known about its effects on plant phenology.Furthermore,no published study has examined effects of N chemical forms on plant phenology.Methods in an alpine meadow on the Tibetan Plateau,we monitored reproductive phenology of six common plant species after 8 years of fertilization with different N chemical forms(addition of 7.5 g N m^(−2) yr^(−1) in the forms of ammonium,nitrate and ammonium nitrate),with no N addition as the control.Important Findings Eight years of N fertilization affected plant reproductive phenology,and such effects depended on the species,N form and phenological phase.Fertilization with ammonium generally delayed,advanced or did not change flowering and fruiting phases of the alpine plants.Furthermore,fertilization with ammonium affected the temporal dispersion of reproductive phenology among the six species,espe-cially among the late-flowering species.This could reduce the overlap of flowering and fruiting and increase phenological com-plementarity.Fertilization with nitrate only delayed the senescence phase of Elymus nutans,and fertilization with ammonium nitrate did not affect reproductive phenology of the six alpine plants.N fertilization with any form increased the overlap in senescence among the six species.We conclude that long-term N fertilization can cause shifts in plant phenology and such effects depend on N chemical forms.Our results also suggest that phenological comple-mentarity could be a mechanism underlying resource partitioning and thus species coexistence in the face of changing N availability with different chemical forms.展开更多
基金National Natural Science Foundation of China(31270503,31570413)an Excellent Scientists grant from the Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences(2011RC101).
文摘Aims Long-term nitrogen(N)fertilization has profound impacts on com-munity structure and ecosystem function,but little is known about its effects on plant phenology.Furthermore,no published study has examined effects of N chemical forms on plant phenology.Methods in an alpine meadow on the Tibetan Plateau,we monitored reproductive phenology of six common plant species after 8 years of fertilization with different N chemical forms(addition of 7.5 g N m^(−2) yr^(−1) in the forms of ammonium,nitrate and ammonium nitrate),with no N addition as the control.Important Findings Eight years of N fertilization affected plant reproductive phenology,and such effects depended on the species,N form and phenological phase.Fertilization with ammonium generally delayed,advanced or did not change flowering and fruiting phases of the alpine plants.Furthermore,fertilization with ammonium affected the temporal dispersion of reproductive phenology among the six species,espe-cially among the late-flowering species.This could reduce the overlap of flowering and fruiting and increase phenological com-plementarity.Fertilization with nitrate only delayed the senescence phase of Elymus nutans,and fertilization with ammonium nitrate did not affect reproductive phenology of the six alpine plants.N fertilization with any form increased the overlap in senescence among the six species.We conclude that long-term N fertilization can cause shifts in plant phenology and such effects depend on N chemical forms.Our results also suggest that phenological comple-mentarity could be a mechanism underlying resource partitioning and thus species coexistence in the face of changing N availability with different chemical forms.
