Study On Soil Greenhouse Gas In Severely Burned Area Of The Greater Khingan Mountains Under Different Restoration Methods

As an important source and sink of atmospheric greenhouse gases(GHG).forest soil plays a crucial role in the process of global warming.Thus,it would have a great significance to study the soil GHG and its influence factors in burned area of the Great Khingan Mountains.It could provide the basis theory for the research of the burned soil GHG at home and abroad,provide theoretical basis for the selection of vegetation restoration methods,mitigation of greenhouse gas emissions from the soil in the burned area and the formulation of carbon emission policies for the local government.In order to learn the intensity of greenhouse fluxes(GHG)source/sink from soil and its influence factors of the three recovery modes forest soil from serious burned area in Greater Khingan Mountains,the soil GHG(CO2、N2O、CH4)was observed by static chamber-GC technique in situ during the growing season.The results showed that:(1)The effects of different restoration methods on diurnal changes of soil temperature,soil moisture,and growth season changes of soil moisture were significant.Soil temperature and humidity change regularly in the growing season.Soil pH and total nitrogen changed significantly in seasons,and soil organic carbon content in naturally renewed forest changed significantly in growth seasons.The restoration method had a significant impact on soil pH,total nitrogen and organic carbon content.(2)The diurnal variation of soil CO2 flux in the three restoration methods was high in day and low in night and the growth season showed a two-peak change rule.The diurnal variation of soil N2O flux was generally high in the day and low in the night,and the three kinds of recovery in the growth season showed a single peak change.The diurnal fluxes of CH4 in woodland soil under different restoration methods were not consistent or even opposite.The artificial promotion of natural regeneration in the growth season showed double-peak changes,while the artificial and natural regeneration showed single-peak changes.Under the influence of soil hydrothermal conditions and physical and chemical properties,the diurnal and diurnal greenhouse gas fluxes of forest soil were affected significantly of the three restoration methods.In the growing season,the woodland soil CO2 emission flux of artificial promotion of natural regeneration(634.40±246.52mg·m’2·h-1)was bigger 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 three recovery methods.The woodland soil CH4 uptake flux of artificial regeneration was significantly higher than that of artificial promotion of natural regeneration.The emissions of N2O from woodland soil of the natural regeneration were significantly higher than the other two restorations methods.(3)The diurnal greenhouse gas flux of forest soil in the three restoration methods was affected by the interaction of soil hydrothermal conditions and vegetation growth.Soil temperature was the key factor affecting the woodland soil greenhouse gas fluxes of three vegetation recovery methods.Soil moisture had a significant effect on N2O fluxes of artificially regeneration’s soils(P<0.01).The soil pH value was only significantly correlated with the CO2 flux from natural regeneration’s woodland soil(P<0.05).The total nitrogen content in soil was only significantly related to the CH4 flux of woodland soil from artificial promotion of natural regeneration(P<0.05).(4)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 effect in artificial promotion of natural regeneration was 1.83×104 kg·CO2hm-2.which in artificial and natural regeneration were 1.74×104 and 1.67×104 kg·CO2hm-2.The CO2 and N2O emissions of forest soils in Amuer region were 8.85×106 t and 1.88×102 t,the absorption of CH4 was 1.05×103t in the annual growth season.