CO2浓度升高与氮添加对三江平原湿地小叶章生长的影响

利用开顶箱薰气室,设置正常大气CO₂浓度(350 μmol·mol^-1)、高CO₂浓度(700 μmol·mol^-1)2个CO₂水平和不施氮(0 g N·m^-2)、中氮(5 g N·m^-2)和高氮(15 g N·m^-2)3个氮素水平,研究CO₂浓度升高和氮肥施用对三江平原草甸小叶章生长的影响.结果表明：随着CO₂浓度升高,小叶章物候期提前,其中抽穗期提前1～2 d,成熟期提前3 d;不施氮、中氮和高氮水平下, CO₂浓度升高使小叶章的分蘖分别增加8.2%(P<0.05)、8.4%(P<0.05)和5.5%(P>0.05);在小叶章生长初期,CO₂浓度升高对其生物量的增加有促进作用,拔节期和抽穗期小叶章地上生物量分别增加12.4%和20.9%(P<0.05);生长后期则对小叶章地下生物量的促进作用增大,腊熟期和成熟期的地下生物量分别增加20.5%和20.9% (P<0.05).小叶章生物量对高浓度CO₂的响应与供氮水平有关，供氮充足条件下, 高浓度CO₂对生物量的促进效应更大.

Effects of elevated atmospheric CO2 concentration and nitrogen addition on the growth of Calamagrostis angustifolia in Sanjiang Plain freshwater marsh.

By using open top chamber, an experiment with two levels of atmospheric CO₂ concentration (350 and 700 μmol·mol^-1) and three levels of nitrogen supply (0, 5, and 15 g N·m^-2) was conducted to investigate the effects of elevated atmospheric CO₂ and nitrogen supply on the growth of Calamagrostis angustifolia in the freshwater marsh of Sanjiang Plain. Under elevated atmospheric CO₂ concentration, the phenophase of C. angustifolia advanced. Jointing stage was advanced by 1-2 d, and maturity stage was advanced by 3 d. Elevated atmospheric CO₂ promoted the tillering of C. angustifolia, with the increment of tiller number under 0, 5, and 15 g·m^-2 of nitrogen supply being 8.2%(P<0.05), 8.4% (P<0.05), and 5.5% (P>0.05), respectively. Elevated atmospheric CO₂ also promoted the aboveground biomass at jointing and heading stages, the increment being 12.4% and 20.9% (P<0.05), respectively, and increased the belowground biomass at later growth stages, with the incrementat dough stage and maturity stage being 20.5% and 20.9% (P<0.05), respectively. The responses of C. angustifolia biomass to elevated atmospheric CO₂ concentration depended on nitrogen supply level. Under sufficient nitrogen supply, the promotion effect of elevated atmospheric CO₂ concentration on the biomass of C. angustifolia was higher.