Lü Xiao-Tao, Dijkstra Feike A, Kong De-Liang, Wang Zheng-Wen, Han Xing-Guo
State Key Laboratory of Forest and Soil Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Department of Environmental Sciences, The University of Sydney, Camden, NSW, 2570, Australia.
Sci Rep. 2014 Apr 28;4:4817. doi: 10.1038/srep04817.
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.
大气氮（N）沉降增加和降水格局改变对半干旱草原的生态系统功能有着深远影响。这两个因素之间的相互作用在很大程度上仍不为人知。在中国北方的一个半干旱草原上进行了一项添加氮和水的田间试验。我们研究了在两个对比明显的水文生长季节中，地上净初级生产力（ANPP）和植物氮利用的响应。添加氮对ANPP没有影响，这可能是由于植物氮吸收增加与植物氮利用效率（NUE）降低之间的抵消作用。添加水显著提高了ANPP，这主要是由于植物地上氮吸收增加。添加氮和水在群落水平上显著相互作用，影响ANPP、植物氮吸收和氮浓度。我们的观察结果突出了植物氮吸收和利用在介导氮和水添加对ANPP影响方面的重要作用。
