科研之友
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摘要
Methane (CH4) is an important anthropogenic greenhouse gas, up to 15% of which is consumed by terrestrial soils. In this field study of the CH4 cycle of a pine forest, 18 plots were established at each of two sites, located 40 m apart. The upper site was well-drained and the lower site was poorly drained, but they shared similar overstory tree composition. Nitrogen was added as NH4NO3 incrementally across the 2009 growing season in a high (67 kg NH4NO3 ha(-1) yr(-1)) and a low (5 kg NH4NO3 ha(-1) yr(-1)) concentration. The sites were monitored for soil and air temperature, soil moisture, precipitation, air pressure, and NH4 and NO2+NO3 concentrations throughout the growing season. Across all treatments for the duration of the field season, average CH4 flux showed consumption of -0.84 kg CH4 ha(-1) yr(-1), but CH4 flux differed between the upper and lower sites. Across all treatments, upper site CH4 flux averaged -5.38 kg CH4 ha(-1) yr(-1), while lower site flux averaged 3.72 kg CH4 ha(-1) yr(-1), with greater variance than was observed at the upper site. High N treatments caused greater CH4 release than the control in the lower, but not the upper, site. The main correlated variable with CH4 flux was soil moisture; however, it accounted for <14% of the variation. Statistics were run several different ways, resulting in multiple environmental factors contributing up to 84% of the variation in CH4 flux. Long-term drainage differences between the sites likely drove the differences in CH4 flux.
- 出版日期2012-7-20
