黔中地区不同植被类型土壤氧化亚氮的释放特征及影响因素

利用密闭箱-气相色谱法于2006—2007年对黔中地区退耕荒草地、灌丛、马尾松林和阔叶林土壤氧化亚氮的释放通量进行原位观测，初步研究了我国南方喀斯特地区不同植被类型土壤N₂O释放量的季节变化.结果表明:除个别月份土壤表现为大气N2O的吸收汇，各观测点均为N₂O的源，植被条件和土壤类型对土壤N₂O的释放具有明显影响.退耕荒草地、灌丛N₂O释放量具有明显的季节变化规律, 春夏季节高于秋冬季节，通量范围分别在-20.7～103.0 μg N·m^-2·h^-1和 -33.0～67.3 μg N·m^-2·h^-1.马尾松林、阔叶林春季土壤N₂O释放量最高，其他季节变化规律不明显，通量范围分别在-5.3～35.0 μg N·m^-2·h^-1和-14.4～152.8 μg N·m^-2·h^-1.相关性分析表明，土壤水分与N₂O释放通量显著负相关，是影响土壤N₂O释放通量季节变化的主要驱动因素.温度通过影响土壤水分而间接影响土壤N₂O的释放通量.

Soil N2O flux and its affecting factors under different vegetations in central Guizhou Province.

By using close chamber-GC method, the N₂O fluxes in de farming grassland, bush land,Pinus massoniana forestland, and broadleaved forestland in central Guizhou were measured in situ in 2006 and 2007 to investigate the seasonal change patterns of soil N₂O flux under different vegetations in karst region of southwest China. The results indicated that in a whole year round, the soils in all test sites played the source of atmospheric N₂O, only acting as a N₂O sink in exceptional months. The soil type and the vegetation had obvious effets on the N₂O flux from soil. Yellow soil had a smaller N₂O flux than calcareous soil, except for broadleaved forestland. The N₂O fluxes from de farming grassland and bush land were higher in spring and lower in autumn and winter, and varied within the range of -20.7-103.09 μg N·m^-2·h^-1 and -33.0-67.3 μg N·m^-2·h^-1, respectively; while those from P. massoniana forestland and broadleaved forestland were the highest in spring but had no definite change patterns in other seasons, and varied within the range of -5.3-35.0 μg N·m^-2·h^-1 and -14.4-152.8 μg N·m^-2·h^-1, respectively. The correlation analysis showed that there existed a negative correlation between soil moisture content and N₂O flux, suggesting that soil moisture was the main factor driving the seasonal change of N₂O flux. Temperature indirectly affected the soil N₂O flux through affecting soil moisture.