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研究大气氮沉降增加情景下北方森林土壤CO2排放通量及其相关控制因子至关重要。在大兴安岭寒温带针叶林区建立了大气氮沉降模拟控制试验,利用静态箱-气相色谱法测定土壤CO2排放通量,同时测定土壤温度、水分、无机氮和可溶性碳含量等相关变量,分析寒温带针叶林土壤CO2排放特征及其主要驱动因子。结果表明:氮素输入没有显著改变森林土壤含水量,但降低了有机层土壤溶解性无机碳(DIC)含量,并增加有机层和矿质层土壤溶解性有机碳(DOC)含量。增氮短期内不影响土壤NH+4-N含量,但促进了土壤NO-3-N的累积。增氮倾向于增加北方森林土壤CO2排放。土壤CO2通量主要受土壤温度驱动,其次为土壤水分和DIC含量。虽然土壤温度整体上控制着土壤CO2通量的季节变化格局,但在生长旺季土壤含水量对其影响更为明显。在分析增氮对土壤CO2通量的净效应时,除了土壤温度和水分外,还要考虑土壤有效碳、氮动态的影响。
It is very important to study the flux of CO2 emissions from the northern forest soils and its related control factors when the atmospheric nitrogen deposition increases. In the cold temperate coniferous forest area of Daxing’anling, a simulated control experiment of atmospheric nitrogen deposition was established. The CO2 fluxes of soil were measured by static box-gas chromatography. Meanwhile, related variables such as soil temperature, water, inorganic nitrogen and soluble carbon were measured, CO2 emission from temperate coniferous forest soil and its main driving factors. The results showed that N input did not significantly change soil water content, but decreased soil dissolved organic carbon (DIC) content and organic matter (DOC) content in the organic and mineral layers. Nitrogen increased short term did not affect soil NH + 4-N content, but promoted soil NO-3-N accumulation. Increasing nitrogen tends to increase CO2 emissions from forest soils in the north. Soil CO2 flux was mainly driven by soil temperature, followed by soil moisture and DIC content. Although soil temperature controlled the seasonal variation pattern of soil CO2 flux as a whole, its effect on soil water content was more obvious during the growing season. In analyzing the net effect of nitrogen on soil CO2 fluxes, in addition to soil temperature and moisture, the effects of soil available carbon and nitrogen dynamics should also be considered.