长白山阔叶红松林土壤N_2O排放通量的变化特征

Variation characteristics of soil N_2O emission flux in broad-leaved Korean pine forest of Changbai Mountain.

采用静态密闭箱 /气相色谱分析方法对长白山阔叶红松林两个样地的N2 O排放通量进行了测定。结果表明 ,凋落物对林地土壤N2 O排放的影响是显著的 ,其对全年N2 O排放的平均贡献率是 36 89%。长白山阔叶红松林土壤是大气N2 O一个重要的源 ,但在极少的天气状况下也能吸收大气中的N2 O ,而起着汇的作用。其排放通量的变化范围是 - 4 1 4 8～ 2 91 84μgN2 O·m-2 ·h-1,平均通量是 6 8 7μgN2 O·m-2 ·h-1,高于其他类型林地的排放通量 ,且变动范围也较其他森林类型大。无凋落物林地土壤N2 O排放通量变化范围是 - 2 3 2 4～ 93 75 μgN2 O·m-2 ·h-1,平均通量为 33 79μgN2 O·m-2 ·h-1。两个样地N2 O排放通量的季节变化特征相似 :夏季N2 O的排放通量最高 ,春季次之 ,秋冬两季较低且趋于平稳。昼夜变化趋势也相似 :N2 O排放通量的最大值都出现在 18∶0 0 ,最小值都出现在 12∶0 0和 14∶0 0。研究还表明 ,林地土壤N2 O的排放通量与地表温度和地下 5cm温度的相关性较好 ,无凋落物的样地N2 O的排放通量仅与地下 5cm温度的相关性较好。

The soil N 2O emission fluxes in the two plots of broad-leaved Korean pine forest were measured by static closed chamber-gas chromatograph in Changbai Mountain.The results showed that litter increased N 2O emission flux of the forest soil by 36.89%.Broad-leaved & Korean pine forest soil of Changbai Mountain was an important source of atmospheric N 2O.But in exceptional weather,it was the sink by absorbing N 2O in the atmosphere.The N 2O emission flux of the forest soil ranged from -41.48 to 291.84?μg·m -2·h -1,with the mean of 68.7?μg·m -2·h -1,which was much higher than other types of forest.Furthermore,its variation range was also broader.The N 2O emission flux range of the litter-free soil was from -23.24 to 93.75?μg·m -2·h -1,with an average of 33.79?μg·m -2·h -1.The two plots showed similar seasonal variations with the highest emission flux in Spring,the higher in Summer and the lower in Autumn and Winter.The diurnal variation was also similar: The maxima of the two plots both occurred at 18 O'clock,and the minima appeared at 12 O'clock and 14 O′,clock.The results also indicated that N 2O emission flux of the forest soil was positively correlated to soil temperatures at 0 cm and 5 cm depth,while N 2O emission flux of the litter-free soil only had relation with the soil temperature at 5 cm depth.