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利用温带森林表层土壤,研究不同低浓度乙炔对土壤硝化和矿化作用及微生物氮含量的影响,同时评价异养硝化对N2O排放的贡献程度以及离树干不同距离对其的影响效应.结果表明,在土壤含水量约为45%WFPS时,与对照(无添加乙炔)相比,10~100Pa乙炔均使土壤N2O释放量显著降低,不同乙炔浓度间无明显差异;异养硝化对土壤N2O释放量的比例在21%~48%之间,距针叶树干越远其比例越高,而阔叶树土壤异养硝化比例与距树干远近无关.在实验条件下10~100Pa乙炔对森林土壤微生物氮含量、氮素净矿化量以及呼吸作用均无显著性影响,而100Pa乙炔能使土壤呼吸呈现降低趋势.基于森林土壤对10Pa乙炔降解快和实验操作的便宜性,选择50Pa乙炔可较方便研究森林土壤N2O排放来源及其影响机制.距树干相同距离,阔叶树土壤N2O和CO2释放量均高于针叶树;同一树种下距树干越远的土壤N2O和CO2释放量越低.逐步回归分析显示,土壤碳总量和水溶性有机碳含量以及pH变化可以有效解释土壤CO2排放量的95%变化;土壤总氮,交换态铵和微生物氮含量可以有效解释所观测N2O排放量的72%变化,其中微生物氮含量能够说明土壤异养硝化的25%变化.不同浓度乙炔干扰下森林土壤N2O和CO2排放量分别与土壤净硝化率有正相关性.
The effects of different concentrations of acetylene on soil nitrification and mineralization and microbial nitrogen content were studied by using the surface soil of temperate forests. The contribution of heterotrophic nitrification to N2O emission and the effect of heterotrophic nitrification on them were evaluated. When soil water content was about 45% WFPS, compared with the control (without adding acetylene), acetylene with 10 ~ 100Pa significantly decreased soil N2O release and had no significant difference among different concentrations of acetylene; , And the proportion of heterotrophic nitrification in the broad-leaved tree had nothing to do with the distance from the tree trunk.Under the experimental conditions, the content of soil microbial nitrogen, nitrogen The amount of net mineralization and respiration had no significant effect, while 100Pa acetylene decreased the soil respiration.Based on the degradation of 10Pa acetylene in forest soils and the cheaper operation of the experiment, 50Pa acetylene could be more convenient to study the soil N2O Emission source and its mechanism of impact.The release of N2O and CO2 from the broad-leaved tree was higher than that of the conifers at the same distance from the trunk, and the release of N2O and CO2 from the farther the tree under the same species The results of stepwise regression analysis showed that soil total carbon, water-soluble organic carbon and pH change could effectively explain 95% change of soil CO2 emissions. Soil total nitrogen, exchangeable ammonium and microbial nitrogen content could effectively explain the observed N2O The change of 72% of the total amount of nitrogen and nitrogen in the soil, which can explain 25% change of soil heterotrophic nitrification.The N2O and CO2 emission of forest soil with different concentrations of acetylene interfere with the net nitrification rate of soil respectively.