Carbon Sequestration Capacity Of Chlorochyma In Tree Branches And Their Contribution To The Forest Carbon Budget

Tree leaf is the main organ of assimilation to fix carbon.Aiming to answer this question, larch,poplar and clove trees were selected as study materials of this study.Firstly,the mineral influrnces on the photosynthesis of leaves and braches were carried out by different mineral element deficinent treatments.Then,the possibility of using spectral parameter to monitoring the chlorophyll contents and photosynthetic capacity of leaves and braches were measured. Thirdly,a field long-term photosynthesis measurement of leaves and branches were measured through year of 2008 to find their environmental relations.Based on the above results,using larch as an example,a comparison between the branch photosynthesis and whole forest net ecosystem exchange(NEE),ecosystem respiration(RE),gross ecosystem production(GEP) and different components of soil respiration(Root respiration,soil microbe respiration and litter respiration)were carried out and finnaly the possible contribution of branches chlorochyma photosynthesis to forest carbon budget were discussed.The following conclusions were got:1,Influences of mineral elements to the photosynthetic function of chlorenyma in tree leaves and branches.Through one-year different mineral elements deficiency(N,P,K,Ca,Mg,B)to Larix gmelinii,Populus alba and Syringa microphylla,we found that one mineral element deficiency could affect the content of another mineral elemnt.For example,the content of N for both leaves and braches was reduced under Mg deficiency.No consistent pattern within different species and organs were found on the influence of mineral elements degiciency to photosynthetic electron transportation rate(ETR).Similarly,no conjstent pattern were found on various photosynthetic C4-enzyme(MDH,PEPC,PEPCK and ME)under such element deficiency treatments.However,the content of C4-enzyme in branches was generally higher than those in leaves in all the three species,indicating that the photosynthesis of branches might be C4 pathway.2,The relations of the spectral parameters and the photosynthetic function of chlorenyma in leaves and branches.The relation of different spectral parameters and the chlorophyll content of leaves was generally better than those of branches.Moreover,more spectral parameters of leaves were correlated with their chlorophyll content with comparing with branches.Several parameters, ZM,BRⅡ,VOG1 and GM2 significantly correlated with the branches Ch1.a+b(mg·g^-1),while the branches Ch1.a+b(mg·m^-2)were significantly correlated with MCARⅡ,RDⅥand NTⅦ. Of them,significant correlations between leaf Ch1.a+b(mg·g^-1)and GM2,and Ch1.a+b(mg·m^-2) and RDⅥwere found,too.By analyzing the rate of ETR and it of ETR/Ch1.a+b on leaves and branches,we found that ETR on leaves generally was higher than those on branches,and the rate of ETR/Ch1.a+b on leaves were higher than on branches in seven specis,and the rate of ETR/Ch1.a+b on leaves were lower than on branches in twelve species.Based on the above result,we can calculate the ETR using the correlations between ETR and Ch1.a+b,because of the value of ETR/Ch1.a+b was stability on the analysis in one tree,and the value of SD was small,too.3,Photosynthetic function was measured for a long-term,and the fixed carbon was calculated in leaves and branches.The chlorophyll season change in branches was not conspicuous comparing with leaves in larch,poplar and clove.The ETR in leaves was higher than in branches of poplar and clove, but it in leaves was little lower than in branches of larch in growing season.In the non-growing season,the value of ETR was 10-50μmol·m^-2·s^-1in the three species,indicating that the ETR in branches was different from leaves.Branches had a significantly exponential correlation between ETR and PAR.These correlations on branches were more significantle than on leaves. y=13.997e^00401xwas the correlation for larch,y=8.3725e^00566xwas the correlation for clove, y=8.7092e^00695xwas the correlation for poplar.Comformming to leaves,the Photo and ETR had a rectangular hyperbola with PAR in branches,and the saturation point was 400umol·m^-2·s^-1. Taken Larix Gmelinii for instance,chlorophyll of carbon sequestration through the ETR and environmental factors calculated by fitting the relationship between:larch tree in the carbon sequestration capacity of 4.09mol·m^-2,leaves of carbon sequestration in 84.82mol·m^-2.4,The carbon cycle measured by the eddy covariance method in larch forest.When the PAR went to 900μmol·m^-2·s^-1,the NEE distributed dispersively at the daytime in the growing season.When the PAR went to 1500μ·mol·m^-2·s^-1,the NEE approached to saturation.In the larch plantation,the result of RE on the estimated total cumulative amount of the maximum appeared in the July to 119.8 g·m^-2·yr^-1,minimum appeared in the January to 26.48 g·m^-2·yr^-1;the NEE in the maximum amount appeared in August to 118.93 g·m^-2·yr^-1;the total volume of NEE was 148.92 g·m^-2·yr^-1.The total volume of RE was 854.71 g·m^-2·yr^-1.GPP in the maximum amount appeared in August to 235.03 g·m^-2·yr^-1;the total volume of GEP was 1003.63 g·m.(-2)·yr^-1.5,The estimation of soil resprition on different components in larch forestThe correlation between soil respiration and soil temperature was significant,and the soil humidity did not affect the calculation.So we used the correlation between soil respiration and soil temperature to calculate the soil respiration.By calculating the total soil respiration of the four forests through the correlations,we can get the result as follows:thinning larch plantation was 86.19mol·m^-2·yr^-1;larch plantation was 80.74mol·m^-2·yr^-1;red pine plantation was 110.56 mol·m^-2·yr^-1;mandshurica plantation was 113.50mol·m^-2·yr^-1.The rate of R_m,R_litterand R_root were 46%,33%and 21%.6,The influence of carbon fixation in branches to carbon cycle in the larch forestBy comparing the fixed carbon between leaves and branches,we can see that the rate was 1:20 on the per-square meters of land area,but 5:4 on there own area.Branches carbon fixation played an important role in the ecosystem.Carbon fixation of branches was 1:4 to the root respiration,and it,occupied 30%of NEE,6.25%of RE,5%of GEP.