Effects Of Liberation Cutting On Greenhouse Gas Emission From The Pinus Koraiensis Plantation On Abandoned-land In The Northeast China

By using of static chamber and gas chromatograph techniques,the CO₂,CH₄ and N₂O emissions fluxes and environmental factors?soil temperature;soil volume water content?of the Pinus koraiensis plantation as well as the farmland under different liberation cutting intensity?non-selective cutting,selective cutting of upper tree layer-50%,clear cutting of upper tree layer-100%,cutting intensity refer to volume percent?were studied.We investigated the influence law and mechanism of afforestation and liberation cutting on greenhouse gas emission,master factor and soil greenhouse gases global warming potential in order to provide scientific basis for quantitative evaluation of the effect of afforestation project in Northeast China.The result shown that:?1?The temperature was significantly reduced by 0.7⁵.0?in spring and summer after Pinus koraiensis plantation in abandoned land.In contrast,The temperature was significantly increased by 0.7⁵.0?,but the annual average temperature was decreased by 0.4².4?.The soil moisture content of average was significantly reduced after Pinus koraiensis plantation.The moisture content of average was significantly reduced in selective cutting of upper tree layer site and the shallow?15⁴0cm?significantly increased in clear cutting of upper tree layer site after liberation cutting.?2?The CO₂ emission flux(151.43²10.27 mg·m^-2·h^-1)was showing non-selective cutting>farmland>selective cutting of upper tree layer>clear cutting of upper tree layer.After50 years of afforestation on abandoned land,the CO₂ emission flux of non-selective cutting increased by 14.6%compared with farmland.And after 40 years of liberation cutting,the CO₂emission flux of liberation cutting had been reduced by 6.0%¹7.5%compared with farmland and by 17.9%²8.0%compared with non-selective cutting.The CH₄ absorption flux(-0.031^-0.045 mg·m^-2·h^-1)in the soil was showing non-selective cutting>clear cutting of upper tree layer>selective cutting of upper tree layer>farmland.The CH₄ absorption flux of non-selective cutting increased by 45.2%compared with farmland,The CH₄ absorption flux of liberation cutting increased by 12.9%³5.5%compared with farmland and reduced by 6.7%²2.2%compared with non-selective cutting.The N₂O emission flux(0.010⁰.037 mg·m^-2·h^-1)in the soil was showing farmland>non-selective cutting>clear cutting of upper tree Layer>selective cutting of upper tree layer.The N₂O emission flux of non-selective cutting reduced by 48.6%compared with farmland,The N₂O emission flux of liberation cutting reduced by 12.9%³5.5%compared with farmland and by 6.7%²2.2%compared with non-selective cutting.?3?The correlation of CO₂,CH₄ and N₂O emission flux with soil and air temperature was not changed after afforestation and liberation cutting,but it changed the correlation between three kinds of greenhouse gases and soil moisture.The positive correlation of CO₂ emission flux with soil and the shallow?5¹0cm?soil moisture content was changed to the significantly positive correlation of CO₂ emission flux with the lower part of the soil layer?20⁴0cm?or0⁴0cm of all soil layer soil moisture content after afforestation and liberation cutting.There was a significant negative correlation between CH₄ and 20cm soil water content in each untreated sample.The positive correlation of N₂O emission flux with soil and the Farmland 20,30⁴0cm soil layer moisture content was changed to the positive correlation of N₂O emission flux with soil with the 15cm soil moisture after afforestation.But comparison to non-selective cutting,there was a significantly positive correlation in selective cutting of upper tree layer and the 15⁴0cm soil moisture content,and there was a significantly positive correlation in clear cutting of upper tree layer and the 25,40cm soil moisture content.?4?The soil greenhouse gases global warming potential(14.16¹8.91t·hm^-2·yr^-1)took on the trends of non-selective cutting>farmland>selective cutting of upper tree layer>clear cutting of upper tree layer,moreover,non-selective cutting increased by 11.0%than farmland,liberation cutting reduced by 9.6%¹6.9%compared with farmland and by 17.8%²5.1%compared with non-selective cutting.Afforestation of Pinus koraiensis plantation on the abandoned land increased the soil greenhouse gases global warming potential,however,the liberation cutting significantly reduced the soil greenhouse gases global warming potential in Northeast of China.So taking the control of the raising temperature effect into consideration,it was the better way for liberation cutting to be taken in Pinus koraiensis plantation on the abandoned land.