摘要:为研究大兴安岭重度火烧迹地在不同恢复方式下林地土壤CO₂、CH₄和N₂O排放特征及其影响因素，采用静态箱/气相色谱法，在2017年生长季（6月-9月）对3种恢复方式（人工更新、天然更新和人工促进天然更新）林地土壤温室气体CO₂、CH₄、N₂O通量进行了原位观测。研究结果表明：（1）3种恢复方式林地土壤在生长季均为大气CO₂、N₂O的源，CH₄的汇；生长季林地土壤CO₂排放通量大小关系为人工促进天然更新（（634.40±246.52）mg m^-2 h^-1） > 人工更新（（603.63±213.22）mg m^-2 h^-1） > 天然更新（（575.81±244.12）mg m^-2 h^-1），3种恢复方式间无显著差异；人工更新林地土壤CH₄吸收通量显著高于人工促进天然更新；天然更新林地土壤N₂O排放通量显著高于其他两种恢复方式。（2）土壤温度是影响3种恢复方式林地土壤温室气体通量的关键因素；土壤水分仅对人工更新林地土壤N₂O通量有极显著影响（P < 0.01）；3种恢复方式林地土壤CO₂通量与大气湿度具有极显著的响应（P < 0.01）；土壤pH仅与天然更新林地土壤CO₂通量显著相关（P < 0.05）；土壤全氮含量仅与人工促进天然更新林地土壤CH₄通量显著相关（P < 0.05）。（3）基于100年尺度，由3种温室气体计算全球增温潜势得出，人工促进天然更新（1.83×10⁴ kg CO₂/hm²） > 人工更新（1.74×10⁴ kg CO₂/hm²） > 天然更新（1.67×10⁴ kg CO₂/hm²）。（4）阿木尔地区林地土壤年生长季CO₂和N₂O排放量为8.85×10⁶ t和1.88×10² t，CH₄吸收量为1.05×10³ t。



Abstract:Global climate change is the focus of humanity's attention. Greenhouse gases (GHG) are a crucial element of this focus. Forests are important for contributing to the maintenance of ecological balance, and forest soils are an important source and sink of GHG to the atmosphere. The study of the GHG from forest soil and its influence factors could assist the deceleration of global warming is highly significant. The Greater Khingan Mountains are often affected by fire and the restoration of severely degraded ecosystems has always been a focus of experts' attention. In 1987, the forest resources were severely damaged in the Greater Khingan Mountains and owing to short growth seasons and cold weather, the local ecological environment had difficulty recovering. The restoration methods affected the soil properties and vegetation of these degraded ecosystems. In order to know the effects of different restoration methods on woodland soil GHG (CO₂, CH₄ and N₂O) emissions, we used a gas static chamber-GC technique to observe the soil GHG in situ from June to September in 2017. The results showed that in the growing season, the forest soil of three restoration methods was the source of atmospheric CO₂ and N₂O, and the sink of CH₄. In the growing season, the woodland soil CO₂ emission flux of artificial promotion of natural regeneration ((634.40±246.52) mg m^-2 h^-1) was greater than artificial regeneration ((603.63±213.22) mg m^-2 h^-1) and natural regeneration ((575.81±244.12) mg m^-2 h^-1). There was no significant difference between the three recovery methods. The woodland soil CH₄ uptake flux of the artificial regeneration was significantly higher than that of the artificial promotion of natural regeneration. The emissions of N₂O from the woodland soil of natural regeneration were significantly higher than the other two restoration methods. During the growing season, the woodland soil greenhouse gas fluxes of the three vegetation recovery methods were markedly different. Soil temperature was the key factor affecting the woodland soil greenhouse gas fluxes of the three vegetation recovery methods. Soil moisture had a significant effect on N₂O fluxes of artificially regenerated soils (P < 0.01). The CO₂ flux of woodland soil had a very significant response to atmospheric humidity. The soil pH value was significantly correlated only with the CO₂ flux from the naturally regenerated woodland soil (P < 0.05) and the total nitrogen content in the soil was only significantly related to the CH₄ flux of woodland soil from the artificial promotion of natural regeneration (P < 0.05). Based on the centennial scale, we calculated the global warming potential (GWP) from three greenhouse gases in three recovery modes. The contribution potential of greenhouse effects in the artificial promotion of natural regeneration was 1.83×10⁴ kg CO₂/hm², and in artificial and natural regeneration were 1.74×10⁴ and 1.67×10⁴ kg CO₂/hm², respectively. The CO₂ and N₂O emissions of forest soils in the Amuer region were 8.85×10⁶ t and 1.88×10² t and the absorption of CH₄ was 1.05×10³ t in the annual growth season. These results provide a scientific basis for the restoration and reconstruction of degraded ecosystems in the Greater Khingan Mountains.





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