Potential fluxes of N₂O and CH₄ from soils of three forest types in Eastern Canada

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• 作者：Sami Ullah ; Rebeccah Frasier ; Leonora King ; Nathalie Picotte-Anderson ; Tim R. Moore
• 关键词：Greenhouse gas fluxes ; C in forest soils ; N in forest soils ; C and N biogeochemistry ; N₂O fluxes ; CH₄ fluxes ; CO₂ fluxes
• 刊名：Soil Biology & Biochemistry
• 出版年：2008
• 出版时间：April 2008
• 年：2008
• 卷：40
• 期：4
• 页码：986-994
• 全文大小：185 K

文摘

We conducted laboratory incubation experiments to elucidate the influence of forest type and topographic position on emission and/or consumption potentials of nitrous oxide (N₂O) and methane (CH₄) from soils of three forest types in Eastern Canada. Soil samples collected from deciduous, black spruce and white pine forests were incubated under a control, an NH₄NO₃ amendment and an elevated headspace CH₄ concentration at 70 % water-filled pore space (WFPS), except the poorly drained wetland soils which were incubated at 100 % WFPS. Deciduous and boreal forest soils exhibited greater potential of N₂O and CH₄ fluxes than did white pine forest soils. Mineral N addition resulted in significant increases in N₂O emissions from wetland forest soils compared to the unamended soils, whereas well-drained soils exhibited no significant increase in N₂O emissions in-response to mineral N additions. Soils in deciduous, boreal and white pine forests consumed CH₄ when incubated under an elevated headspace CH₄ concentration, except the poorly drained soils in the deciduous forest, which emitted CH₄. CH₄ consumption rates in deciduous and boreal forest soils were twice the amount consumed by the white pine forest soils. The results suggest that an episodic increase in reactive N input in these forests is not likely to increase N₂O emissions, except from the poorly drained wetland soils; however, long-term in situ N fertilization studies are required to validate the observed results. Moreover, wetland soils in the deciduous forest are net sources of CH₄ unlike the well-drained soils, which are net sinks of atmospheric CH₄. Because wetland soils can produce a substantial amount of CH₄ and N₂O, the contribution of these wetlands to the total trace gas fluxes need to be accounted for when modeling fluxes from forest soils in Eastern Canada.