Wang Ying, Wang Chuan-Kuan, Fu Min-Jie, Liu Shi, Wang Xing-Chang
College of Forestry, Northeast Forestry University, Harbin 150040, China.
Ying Yong Sheng Tai Xue Bao. 2009 May;20(5):1007-12.
Seasonal dynamics of N2O flux and its controlling factors for four representative temperate forests in northeastern China were examined with a static closed chamber-gas chromatograph technique. These forests were Korean pine (Pinus koraiensis) plantation, Dahurian larch (Larix gmelinii) plantation, Mongolian oak ( Quercus mongolica) forest and hardwood broadleaved forest (dominated by Fraxinus mandshurica, Juglans mandshurica, and Phellodendron amurense). The results showed that all ecosystems were overall atmospheric N2O source during the growing season. The N2O flux (microg x m(-2) x h(-1)) decreased in order of the hardwood broadleaved forest (21.0 +/- 4.9) > the pine plantation (17.6 +/- 4. 6) > the larch plantation (9.8 +/- 5.9) > the oak forest (1.6 +/- 12.6). Overall, there was no consistent seasonal pattern in N2O flux for the four ecosystems. The N2O flux was significantly positively correlated to soil gravimetric water content (0-10 cm depth) consistently for all ecosystems, but significantly negatively correlated to NO3(-)-N content for each ecosystem. However, the responses of N2O flux to soil temperature and NH4(+)-N differed among the ecosystems. The N2O fluxes for the coniferous plantations were positively correlated to NH4(+)-N, but not correlated to the soil temperature at 5 cm depth; while those for the broadleaved forests displayed an opposite trend. The soil water content was the dominator of soil N2O emission for the forests in 2007 perhaps resulting from relative drought in the year. Interactions of vegetation type, environmental factor, and nitrogen availability to soil N2O emission should be further studied in the future.
采用静态密闭箱-气相色谱技术，研究了中国东北4种典型温带森林N2O通量的季节动态及其控制因素。这些森林分别是红松人工林、落叶松人工林、蒙古栎林和硬阔混交林（以水曲柳、胡桃楸和黄波罗为主）。结果表明，所有生态系统在生长季均为大气N2O的源。N2O通量（μg·m-2·h-1）大小顺序为：硬阔混交林（21.0±4.9）＞红松人工林（17.6±4.6）＞落叶松人工林（9.8±5.9）＞蒙古栎林（1.6±12.6）。总体而言，4种生态系统的N2O通量均无一致的季节变化规律。所有生态系统的N2O通量均与土壤质量含水量（0-10cm深度）显著正相关，但与各生态系统的NO3--N含量显著负相关。然而，不同生态系统中N2O通量对土壤温度和NH4+-N的响应不同。针叶人工林的N2O通量与NH4+-N正相关，但与5cm深度的土壤温度无关；而阔叶林则呈现相反趋势。2007年，土壤水分含量是森林土壤N2O排放的主要控制因素，这可能是由于当年相对干旱所致。未来应进一步研究植被类型、环境因子和氮有效性对森林土壤N2O排放的交互作用。
