The Research Of Correlativity Between North Subtropical Secondary Oak Forest Ecosystem Carbon Budget And Asymmetrical Environmental Factors

In order to study the response mechanism between photosynthesis, respiration andenvironmental factors in the oak forest ecosystem,predict the future global climate changetrends,the eddy covariance method was used to monitor CO2flux and meteorological factors inNorth subtropical secondary oak forest ecosystem of the Changjiang River Delta Urban ForestEcosystem Research Station for one year(Dec.2010—Nov.2011),the results were showed asbellow:The CO2fluxes showed roughly the same diurnal variation in four different seasons,the oakecosystem released CO2all the night,it began to absorb CO2after sunrise,the absorptionmaintained at a large level from10:00am to14:00pm,it released CO2again after the sun wentdown. The CO2absorption in summer was significantly higher than the other three seasons,itreached the maximum absorption0.49mg m-2s^-1at11:30and the maximum emission0.082mg m-2s^-1at03:30. The variation range of CO2flux was the largest in summer as it was0.572mg m-2s^-1.The ecosystem showed strong carbon sink in growing season and showed carbon source orweak carbon sink in non-growing season. In December and January,it showed carbon source,themonthly total carbon emissions was15.36g m-2month^-1and31.92g m-2month^-1,theecosystem began to change to carbon sink from March,and reached the maximum amount ofcarbon sinks at July. The ecosystem showed for the total amount of carbon sink variedfrom-27.81g m-2month^-1to^-169.50g m-2month^-1,the total amount of carbon sinks of thewhole year was-662.10g m-2a^-1.Northern subtropical secondary oak forest ecosystem carbon flux and PAR showed asignificant negative logarithm correlation,the fit of the symmetric time was better than theasymmetric time in different seasons. The carbon flux and air temperature in different rangesshowed a significant negative logarithm correlation,the fit of the symmetric time was better thanthe asymmetric time. The carbon flux and soil temperature in different ranges showed asignificant logarithm correlation,the fit of asymmetric time was better than the symmetric timein different seasons. Comprehensive analysis showed that PAR is the dominant factor to affectthe carbon flux of North subtropical secondary oak forest ecosystem.