Short-term effect of increasing nitrogen deposition on greenhouse gas emissions in Zoige wetland, western China.

Elevated anthropogenic N input could affect the greenhouse gas emissions through influencing the availability of soil nitrogen (N), and ultimately lead to significant changes in the climate and ecological environment. Our experiment was conducted in the Zoige peatland, which is situated in the eastern Qinghai-Tibetan Plateau in China, with pronounced frigid temperate zone, semi damp grass land and humid climate. In order to explore the effect of nitrogen deposition on production and emission of greenhouse gases (CO2, CH4 and N2O) from peatland during its growth cycle (from May to September), four different levels of nitrogen fertilizer application were designed as control (0 kg/(haa), CK), low nitrogen (10 kg/(haa), LN), medium nitrogen (20 kg/(haa), MN) and high nitrogen (80 kg/(haa), HN), and static closed chamber combined with a gas chromatograph technique was used to measure the fluxes of three greenhouse gases. The investigation showed that the mean fluxes of CO2, CH4 and N2O were 224.96113.875, 0.1140.002, 0.0590.003 mg/(m2h) with HN level, 303.80111.397, 0.1110.002, 0.0470.004 mg/(m2h) with MN level and 212.7315.847, 0.0830.004, 0.0320.002 mg/(m2h) with LN level, which were all significantly higher than that of control. N application had a strong promotion to seasonal cumulative emissions of CO2, CH4 and N2O (P0.05). There were significantly positive correlations between increments of greenhouse gas fluxes and soil inorganic nitrogen in N treatments (P0.05), as well as a markedly positive correlation between growth in CO2, CH4 fluxes and biomass increment (P0.05); however, the correlation between incremental greenhouse gases fluxes and soil temperature or moisture factors did not change significantly due to N addition (P0.05). Also, N application significantly increased the global warming potential (GWP) of peatlands (P0.05). These results suggest that the short-term N addition would be likely to stimulate greenhouse gas fluxes in the Zoige peatland by increasing available N content and promoting plant growth. This provides a scientific basis for predicting greenhouse effect caused by N deposition in peatland soil, as well as reasonably protecting the plateau wetland ecosystem.