Research On Carbon Sink/source Of Plantation And Farmland In Chongming

The increased CO2concentration of atmospheric is the main reason caused the globalwarming,so how to reduce CO2concentration draws great attention in the internationalcommunity.There is530million hectare plantation in our country now,but there are few studieson carbon sequestration and carbon balance in plantation and farmland,especially in thesubtropics.Cinamomum camphora and Ginkgo biloba are the most important forest species inChina.Brassica oleracea var.acephala is a popular vegetable food.Based on biomassinventory,soil section,chemical analysis,this paper had researched the carbon balance of theplantation and farmland in chongming modern agricultural zone that would provide essential databases for the research on carbon sink/source in chongming even in our country.The resultsshowed:（1） The average carbon content in all Cinamomum camphora organs were0.4466-0.4726.The order for trunk,root,branch and leaf was0.4726,0.4698,0.4654and0.4466.The average carbon content in all Ginkgo biloba organs were0.4317-0.4751.Theorder for trunk,root,branch and leaf was0.4751,0.4687,0.4593and0.4317.The minimum valuecarbon content of cauliflower was0.2936.The maximum value carbon content of cauliflower was0.4156,and the average value carbon content was0.3413.（2） The carbon content of soil layer in Cinamomum camphora and Ginkgo biloba werebetween3.77（-1）1.91g·kg^-1and1.38（-1）1.46g·kg^-1,The carbon content of soil layer in cauliflowerwas between4.25（-1）5.62g·kg^-1.The carbon storage of Cinamomum camphora was151.82t·hm^-2,the arbor layer and soil layer carbon storage were52.63t·hm^-2and99.19t·hm^-2.Thecarbon storage of Ginkgo biloba was136.15t·hm^-2,the arbor layer and soil layer carbon storagewere44.02t·hm^-2and92.13t·hm（-2）.In the farmland,when harvested after ripening,the carbonstorage of cauliflower vegetable layer was5.89t·hm^-2,soil layer was117.87t·hm^-2,the totalcarbon storage of cauliflower was123.76t·hm^-2.（3） The annual amount of Cinamomum camphora and Ginkgo biloba litter fall were4.41t·hm^-2and3.46t·hm^-2respectively.The most part of litter fall was deciduous,reached88%and80.3%respectively,both of the two plantations.The maximum value litterfall(0.912t·hm^-2)appeared in April in Cinamomum camphora plantation,while the maximumvalue litter fall(0.858t·hm^-2)appeared in November in Ginkgo biloba plantation.Average carboncontent of litter fall were0.4739and0.4538for the two plantations.The litter fall carbonsequestration of the two plantations were2.09t·hm^-2and1.57t·hm^-2.（4） The soil respiration showed distinct seasonality of the two plantations, being summer>spring>autumn>winter.Annual soil heterotrophic respiration C effluxes for the twoplantations were3.06t·hm（-2）and2.56t·hm^-2.Soil heterotrophic respiration C effluxes for thecauliflower farmland was2.65t·hm^-2,in one growth period.（5） In one growth period of cauliflower farmland, when pesticide and fertilizer were used,they caused0.22tC·hm（-2）and0.59tC·hm^-2respectively, totally caused the emission of0.81tC·hm^-2. Irrigation and harvest caused the emission of0.994tC·hm^-2and0.056tC·hm^-2.So,thetotal emission was1.86tC·hm^-2.（6） Annual net carbon sequestration was7.8t·hm^-2(28.6tCO2·hm^-2)in Cinamomumcamphora plantation,while6.35t·hm^-2(23.28tCO2·hm^-2)in Ginkgo biloba plantation,and for thecauliflower farmland,in one growth period,net carbon sequestration was1.38t·hm^-2(5.06tCO2·hm^-2).