The Emissions Of Greenhouse Gases From Larix Gemlini Swamps Soils In XiaoXing'An Mountains Of China

The seasonal variation, diurnal variation and the main influence factors of emission fluxes of Greenhouse gases (CO₂, N₂O and CH₄) of three typical coniferous forest swamp (Larix gmelini Carex swamp, L. gmelini Moss swamp and L. gmelini Sphagnum swamp) were studied by static opaque chamber-GC technique in Xiaoxing(?)an Mountain during 2007-2008. Also we discussed the source and sink relationship of Greenhouse gas. The results showed that:â‘ the CO₂ emission fluxes of three type swamp in growing season were all summer>spring>autumn in 2007, and this was mainly affected by the temperature of upper 30cm soil; in the year 2008, except the L. gmelini Carex swamp follow the laws of 2007, the other two types of swamp's emission fluxes were all spring> summer>autumn, and these three types of swamp were mainly affected by the temperature of upper 20cm soil; the average CO₂ emission fluxes in growing season in 2007 were separately increase 33.7%,35.1%,13.0%.â‘¡The diurnal CO₂emission fluxes of these three typical coniferous forest swamp in growing season were mainly stronger in daytime and weaker at nighttime(except the L. gmelini Sphagnum swamp was stronger at nighttime and weaker in daytime). The air and upper soil temperature were the main influence factors of CO₂ diurnal emission fluxes in spring and autumn, while the deeper soil temperature was the main influence factor in summer.â‘¢the three typical Larix swamp were all emission source of CO₂ in growing season, but there were some differences among them. The CO₂ emission amount was L. gmelini Carex swamp (22.010t hm^-2 yr^-1) >L. gmelini Moss swamp (18.535t hm^-2 yr^-1) >L. gmelini Sphagnum swamp (17.494t hm^-2 yr^-1) in 2007; while in 2008, it was L. gmelini Carex swamp (18.654t hm^-2 yr^-1) >L. gmelini Sphagnum swamp (17.55t hm^-2 yr^-1) >L. gmelini Moss swamp (15.282t hm^-2 yr^-1) .â‘£the three typical Larix swamp CH₄ emission fluxes in 2007 were separately weak emission in spring, strong absorption in summer, zero emission in autumn; weak emission in spring, weak absorption in summer, strong absorption in autumn; and weak emission in spring, strong emission in summer, strong absorption in autumn. While in 2008, the CH₄ emission in growing season of L. gmelini Carex swamp and L. gmelini Moss swamp were all emission in spring, summer and autumn, and L. gmelini Sphagnum swamp was emission in spring and autumn, and absorption in summer; the water table was the main influence factor of CH₄ emission fluxes in 2007 and 2008. The average emission fluxes of these three typical Larix swamp were separately increased 806.3%,233.3%,100% in 2008.â‘¥The soil of three forested swamp communities all were weak sink of CH₄ in two seasons(except L. gmelini Sphagnum swamp was weak source of CH₄ in 2007), but there was different in all communities. The order of absorption of CH₄ from soil was Larix gmelini Moss swamp(-1.200kg hm^-2 yr^-1) Larix gmelini Carex swamp(-1.152kg hm^-2 yr^-1)> Larix gmelini Moss swamp(emission: 0.168kg hm^-2 yr^-1) in 2007; the order of absorption of CH₄ from soil was Larix gmelini Carex swamp(-0.689kg hm^-2 yr^{- 1}) > Larix gmelini Moss swamp(-0.256kg hm^-2 yr^-1) > Larix gmelini Sphagnum swamp(-0.195kg hm^-2 yr^-1) in 2008.⑦The laws of seasonal variation of diurnal N₂O emission fluxes of these three typical Larix swamp was clear different. The order of emission fluxes of N₂O from Larix gmelini Carex swamp, Larix gmelini Moss swamp, Larix gmelini Sphagnum swamp resectively were:summer>spring>autumn, spring>summer>autumn(zero emissions),autumn>spring>summer. The lower water table and higher upper temperature of soil were main influence factors of emission of N₂O in 2007. The order of emission fluxes of N₂O from Larix gmelini Carex swamp,Larix gmelini Moss swamp,Larix gmelini Sphagnum swamp resectively were: spring > summer >autumn,summer>spring> autumn,summer>autumn>spring.The water table and temperature were main influence factors of emission of N₂O in 2008.The average emissions of N₂O from soil were 23%,1182.1%,1328.6% higher in 2007(31, 5 and 10μg m^-2 h^-1) than in 2008(31.8, 0.39 and 0.07μg m^-2 h^-1).⑧the order of diurnal variation of emission fluxes of N₂O from Larix gmelini Carex swamp,Larix gmelini Moss swamp,Larix gmelini Sphagnum swamp resectively all were: daytime>nighttime(except the Larix gmelini Sphagnum swamp was nighttime >daytime in autumn) in spring, summer, autumn. Air temperature was main influence factor of diurnal emission of N₂O from Larix gmelini swamp in spring and summer, soil temperature was main influence factor of diurnal emission of N₂O from Larix gmelini swamp in autumn.⑨The soil of three forested swamp communities all were weak source of N₂O in two seasons. The order of emissions of N₂O from soil was Larix gmelini Carex swamp(1.128kg hm^-2 yr^-1) > Larix gmelini Sphagnum swamp(0.360kg hm^-2 yr^-1)> Larix gmelini Moss swamp(0.192kg hm^-2 yr^-1) in 2007; the order of emissions of N₂O from soil was Larix gmelini Carex swamp(1.198kg hm^-2 yr^-1) > Larix gmelini Moss swamp(0.0159kg hm^-2 yr^-1) > Larix gmelini Sphagnum swamp(0.0028kg hm^-2 yr^-1) in 2008.