为深入认识高寒草甸温室气体通量对长期气候变暖的响应,利用开顶式生长室(OTC,Open Top Chamber)模拟增温2a(2Y,2015-2016年)和6a(6Y,2011-2016年)对藏北高寒草甸生长季CO_2、CH_4和N_2O通量的影响。结果表明:与对照相比,生长季(6-8月)增温6Y处理和增温2Y处理分别增加和降低高寒草甸土壤CO_2排放通量,其中7月增温6Y处理CO_2排放通量显著高于增温2Y处理;增温6Y和2Y处理增加了高寒草甸CH_4吸收通量,但是处理间差异均不显著;高寒草甸N_2O排放通量表现为增温6Y>2Y>CK,处理间无显著差异。环境因子与温室气体排放通量的相关分析表明,CO_2、CH_4和N_2O排放通量与0~ 5cm土壤温度相关不显著;土壤湿度、植物地上生物量、微生物生物量碳和蔗糖酶是影响高寒草甸CO_2排放通量的关键因子;NO_3~--N是影响CH_4吸收通量的关键因素;脲酶和NO_3~--N是影响N_2O排放通量的主要因子。因此,增温6Y处理通过增加植物地上部生物量、蔗糖酶活性,从而提高了土壤CO_2排放通量,增温6Y和2Y处理通过增加土壤脲酶和NO_3~--N含量,从而促进了土壤N_2O排放和CH_4的吸收通量。
英文摘要:
To explore the effects of long-term climate warming on greenhouse gases(GHGs) flux in the alpine meadow,the simulated warming 2 years(2Y,2015-2016) and 6 years(6Y,2011-2016) experiments were conducted by the open top chamber(OTC) in an alpine meadow of Tibetan Plateau,then the dynamics of CO_2,CH_4 and N_2O fluxes were measured during growing season.The observations showed that the CO_2 flux during growing season was increased with 6Y and decreased with 2Y warming treatment,respectively,compared with the control.And the CO_2 flux with 6Y warming treatment was significantly higher than that of 2Y treatment in July.The CH_4 absorption flux was increased with 6Y and 2Y warming treatment,but the differences between treatments were not significant in the growing season.The N_2O emission flux was showed 6Y>2Y>CK in the growing season,and the differences between treatments were not significant.The relationship between environmental factors and GHGs flux were analyzed by using of correlation analysis.The relationship between CO_2,CH_4 and N_2O fluxes and soil temperature(0-5cm) was not obvious.The soil moisture,aboveground biomass,microbial biomass carbon and invertase were key factors regulating the CO_2 fluxes,NO_3~--N was mainly factor affecting the CH_4 absorption flux,and NO_3~--N and soil urease were the main factors promoting N_2O emission flux.Therefore,the CO_2 flux was promoted by increasing plant biomass and invertase activity with 6Y warming treatment,and the N_2O emission and CH_4 absorption flux were improved by increasing the soil urease and NO_3~--N content with 6Y and 2Y warming treatment.