Researches On Aboveground Carbon Storage And Energy Of North Subtropical Quercus Acutissima Plantations

With global warming, more attention have been paid to carbon source or sink.As the largestterrestrial ecosystem organic carbon pool, a great impact would be exerted on atmospheric CO2concentration by any change of carbon storage of forest ecosystem.Forest ecosystem has greatsignificance for increasing carbon sinks,offsetting CO2emissions, and mitigating greenhouseeffect.In this paper,north subtropical Quercus acutissima were selected to study. The studies werefocused on biomass and carbon content of aboveground tree layer, shrub layer, herb layer andlitter, and the carbon content in the soil，building regression model of aboveground tree-layerbiomass.Biomass,carbon storage per unit area and standing crop of energy distributingcharacteristics of Quercus cutissima were studied.The aim was to understand the carbon sinkfunction of Quercus acutissima in the hope of supplying data and laying basis for researches oncarbon sink functions and carbon circle of the regional forest ecosystem in China.Main findingsare as followed:(1)Regression models of biomass of different organs of Quercus cutissima aboveground treelayer were established based on the regression model W=aDb. The results showed that: the totalbiomass of Quercus cutissima is136.77t/hm~2.Tree layer biomass was the largest about132.15t/hm~2.Trunk biomass was the main part of tree layer. Shrub layer biomass was about0.94t/hm~2,herb layer biomass was about0.27t/hm~2,litter layer biomass was about0.27t/hm~2.Thedistributing sequence of the biomass of Quercus cutissima is: Tree layer>litter>shrub layer>herblayer.(2)The carbon content differentiated in the aboveground organs of the tree layer,thedifference was significant. Average carbon content of the aboveground tree layer was43.99%～46.31%,the sequence of carbon content of organs was: trunk>leaf>bark>branch.Average carboncontent of shrub layer,herb layer and litter was37.04%, the sequence of layers was: litter> shrublayer> herb layer.The carbon content of shrub layer,herb layer and litter didn’t vary uniformlywith the age change.The carbon content sequence of under storey in different age was: litterlayer>shrub layer>herb layer.The carbon content in tree layer increased with the increase ofage.The carbon content of shrub layer,herb layer and litter didn’t vary uniformly with the agechange.Soil carbon content in different was between1.00%and4.64%.The mean carbon contentwere3.31%,1.74%,1.31%,repectively of0~20cm,20~40cm and40~60cm.The soil carbon contentdecreased with the increase of age.(3)Carbon storage per unit area of forest ecosystem was141.87t/hm~2,The aboveground treelayer carbon storage per unit area was60.73t/hm~2.The proportion increase with the increase of age.The mean soil carbon storage per unit area was79.34t/hm~2.Soil carbon storage per unit areagenerally increased with the increase of forest age and gradually reduced from top to down.Themean carbon storage per unit area were0.35t/hm~2and0.09t/hm~2,repectively of shrub layer andherb layer.Litter carbon storage per unit area was1.37t/hm~2,accounting for75.86%of understorey. It was a major carbon pool of under storey.(4)The average gross caloric value of aboveground tree layer was74.18KJ/g, The grosscaloric value was highest in leaf,was20.07KJ/g, accounting for55.12%, the sequence of organswas: trunk>leaf>bark>branch. The average value of ash content was5.55%, the ash content washighest in leaf, the sequence of ash content of organs was: leaf>bark>branch>trunk. The averageash-free caloric value was78.58KJ/g, the ash-free content was highest in leaf,was21.53KJ/g.The ash-free caloric value were18.33KJ/g～22.44KJ/g for Quercus cutissima in varyingages.(5)Standing crop of energy of Quercus cutissima Ecosystem was987466KJ/m2,it was980258KJ/m2in aboveground tree layer, accounting for99.27%,the sequence of organs was:trunk>branch>bark>leaf.The Standing crop of energy were1588KJ/m2,5200KJ/m2and420KJ/m2,repectively of shrub layer,litter and herb layer.