Plant nitrogen uptake drives responses of productivity to nitrogen and water addition in a grassland.
Increased atmospheric nitrogen (N) deposition and altered precipitation regimes have profound impacts on ecosystem functioning in semiarid grasslands. The interactions between those two factors remain largely unknown. A field experiment with N and water additions was conducted in a semiarid grassland in northern China. We examined the responses of aboveground net primary production (ANPP) and plant N use during two contrasting hydrological growing seasons. Nitrogen addition had no impact on ANPP, which may be accounted for by the offset between enhanced plant N uptake and decreased plant nitrogen use efficiency (NUE). Water addition significantly enhanced ANPP, which was largely due to enhanced plant aboveground N uptake. Nitrogen and water additions significantly interacted to affect ANPP, plant N uptake and N concentrations at the community level. Our observations highlight the important role of plant N uptake and use in mediating the effects of N and water addition on ANPP.
State Key Laboratory of Forest and Soil Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Xiao-Tao
XT
Lü
Department of Environmental Sciences, The University of Sydney, Camden, NSW, 2570, Australia.
Feike A
FA
Dijkstra
School of Life Sciences, Henan University, Henan 475004, China.
De-Liang
DL
Kong
State Key Laboratory of Forest and Soil Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Zheng-Wen
ZW
Wang
State Key Laboratory of Forest and Soil Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Xing-Guo
XG
Han
D002681:China; D017753:Ecosystem; D065948:Grassland; D009584:Nitrogen / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D014867:Water
D012987:Soil; D014867:Water; D009584:Nitrogen