林火干扰和木炭管理对兴安落叶松林冻土温室气体通量的影响

Global warming resulted by the increase of atmospheric concentration of greenhouse gases (GHG) , mainly carbon (CO2), methane (CH4), and nitrous oxide (N2O) , is a major environmental issue today. Forest fire is a major disturbance in boreal forests, with its occurrence closely coupled to global warming. Higher latitude ecosystems are particularly vulnerable to climate change due to the large amount of carbon in northern latitude soils and the predominance of permafrost. Therefore, changes in climate will result in change to the fire regime as well. The permafrost in Daxinganling is closely linked to the sensitivity of fire disturbance because of its thin soil layer and the southern upper limitis distribution of Euro-Asia permafrost. .Forest fire affect both carbon (C) and nitrogen (N) Cycling in forest ecosysytem, and thereby influence the soil-atmosphere exchange of CO2, CH4, and N2O. To determing the possible changes in soil propertities and GHG fluxes following different intensity forest fires both in a chronosequence of different intervals of time-since-fire, we will establish four fire vestige（light fire, moderate fire, severe fire）, ie in 1987, 2003, 2007, 2010, which represent 26 year, 10 years, 7 years and 3 years time-since-fire, respectivily. Furthmore, we will arrange a different intensity surface fire in Larix gmelinii forest, to determine the effect of different charcoal treats which formed in the fire on the soil propertities and GHG fluxes. We will establish four treatments, having four replication each: a control plot (CK), a plot burned (Burn), a plot burned but with removal of the resulting carcoal (Burn-REM) and a plot burned both buried the charcoal under the forest soil (Burn-BUR).Soil GHG fluxes and various properties of the soil will be determined on unregular time interval using static chamber-gas chromatograph technique. We will also research the effects of charcoal formed in incubation at different temperature on soil properties and GHG fluxes by amending the charcoal to forest soil in a lab experiment. .In conclusion, our study will demonstrates the real Larix gmelinii forest soil characteristic for GHG resource or sink after fire disturbed and with different forestry managements in cold temperate zone, which will provide a detailed GHG account gist and the theory foundation for sustainable development of boreal forest.

气候变暖已经是不争的事实。大兴安岭多年冻土区处于欧亚大陆冻土带南缘，土层较薄，对气温升高和外界变化极为敏感。林火是该地区的重要干扰因子，因此林火干扰下多年冻土区土壤温室气体的排放值得高度关注。本研究依托内蒙古大兴安岭森林生态系统国家野外台站，利用静态箱-气相色谱法，研究我国寒温带兴安落叶松林在不同强度火灾、不同干扰时间序列上土壤性质及地-气温室气体（GHG）通量的可能变化；研究野外条件下火灾发生后采取的不同林业管护措施（火场清理和掩埋处理）对土壤性质及GHG通量的影响；室内条件下利用不同温度（模拟野外条件下不同火烧强度）林木材料高温裂解形成的木炭与土壤的混合培养试验，测定木炭添加对土壤性质及GHG通量的影响，明确该地区在林火干扰及人为影响下温室气体的源汇特征，并探讨其可能的影响机理，为该地区GHG排放提供地带性基础数据，同时也为北方森林生态系统火烧迹地的经营管理提供科学的理论依据。

林火是森林生态系统重要的干扰因子。依托内蒙古大兴安岭森林生态站，研究大兴安岭林区不同时间序列火灾对土壤性质及温室气体通量的影响。结果表明：火烧后土壤微生物数量的数量得到明显提高，火烧10和13年后，土壤细菌、真菌、放线菌的数量较对照分别平均增加了96.2、117.2、105.6 万株/g 和 99.8、93.8、100.5 万株/g。火烧发生 0、8、19、28 年后，土壤 pH 分别较对照增加了 7.7%、2.0%、3.4%、4.0%；有机质含量别较对照降低了 63.8%、26.6%、35.3%、11.3%，全氮含量分别较对照降低了 53.2%、19.7%、21.7%、16.2%；土壤有效氮含量在 0 年和 8 年后分别较对照降低了 28.1%和 9.5%， 19 年后较对照增加了 16%；28 年后土壤有效氮含量与对照无显著差异。CH4平均吸收通量在火烧发生 0、8、19 年后，较对照分别下降了 51.0%、45.0%、7.1%，火烧发生 28 年后与对照相比差异不显著。火烧发生当年，CO2 通量较对照增加了 64.5%。火烧发生当年，N2O排放通量较对照增加 69.2%。火烧发生 8、19、28 年后N2O排放通量分别较对照减少了 5.6%、14.6%、37.9%。火灾迹地土壤CH4气体通量与有机质关联度最高，与速效氮和全氮关联度大致相同。CO2通量与有机质的关联度最高；土壤N2O气体通量与土壤全氮关联度最高。生物质炭能有效改良退化土壤、固碳减排以及减缓大气温室效应。不同施肥处理对当季土壤pH无显著影响，土壤有机质含量分别较对照增加了34.3%和30.8%。碱解氮的季节变化不明显，除M40之外其他所有施肥处理都没有改变土壤碱解氮的含量。生长季结束后，化肥和生物质炭处理土壤全氮含量分别较开始增加了62.0%-68.3%和27.7%-48.0%。施化肥和生物质炭CO2通量分别较对照增加了24.6%和17.6%，两种肥料及同种肥料两个施肥梯度之间CO2通量均无显著差异。施化肥处理显著增加了土壤N2O的排放，生物质炭处理土壤N2O排放在整个试验期间均与CK无差异。H40、H80、M40、M80的增温潜势分别较对照增加了24.2%、26.3%、17.1%、17.8%，施用炭基肥降低了单位植物产量的温室气体排放强度，其中M40、M80分别降低了10.5%和13.8%。