Study On The Characteristics Of Forest Structure And Carbon Sequestration Of Four Plantations And Their Relevance In Huangqian Watershed

The Huangqian watershed of Tai'an is located in The National Key Administrative areas of Mountain Tai and Mountain Yimeng.Quercus acutissima forest,Robinia pseudoacacia forest,Pinus densiflora forest and mixed forest of Quercus acutissima and Pinus densiflora(short for"mixed forest")are Main afforesting trees in this area,which have played important ecological functions in soil improvement,carbon sequestration and oxygen release,and climate regulation.In order to reveal the influence mechanism of different forest structures on the carbon sequestration function and carbon sequestration potential of forest vegetation,based on the Huangqian watershed,this paper choose Quercus acutissima forest,Robinia pseudoacacia forest,Pinus densiflora forest,mixed forest and grassland(control)as the research object,using the method of field investigation and indoor analysis,through surveying the forest structure and biomass index,measuring the carbon content of each organ of forest and soil,calculating and analyzing forest carbon stock and forest carbon density,systematic studying the characteristics of forest structure,forest biomass,forest carbon density and forest carbon stock.Applying methods of principal component analysis and correlation analysis,we have quantitative analyzed coupling relationship of forest structure and carbon sequestration function and discussed the different stand structure on the impact of forest carbon sequestration function,in order to provide scientific basis for quantitative research of vegetation restoration and carbon sequestration of ecological afforestation and choosing forestation tree species in Taiyi mountain area.The main findings are as follows:(1)The structural characteristics of the four plantations in Huangqian watershed are significantly different.The overall performance of non-spatial forest structure is as follows:the DBH of Quercus acutissima forest and mixed forest was significantly higher than that of Pinus densiflora forest and Robinia pseudoacacia forest.The height of Quercus acutissima forest was significantly higher than that of mixed forest,Robinia pseudoacacia forest and Pinus densiflora forest,and there was no significant difference between mixed forest and Robinia pseudoacacia forest.The density of Robinia pseudoacacia forest and Pinus densiflora forest was significantly higher than that of mixed forest and Quercus acutissima forest.The overall performance of spatial forest structure is as follows:In terms of uniform angle index,Quercus acutissima forest was from uniform to random distribution state,while Robinia pseudoacacia forest,Pinus densiflora forest and mixed forest were in random distribution state.In terms of dominance,Quercus acutissima forest and Robinia pseudoacacia forest were in the middle state,Pinus densiflora was from middle to inferior state,and Mixed forest was from subdominance to middle state.In terms of mingling,the mingling of mixed forest was in the middle mixed state,while the mingling of other forests was 0.(2)The forest biomass of four kinds of plantations in Huangqian watershed is as follows:mixed forest>Quercus acutissima forest>Pinus densiflora forest>Robinia pseudoacacia forest;the tree layer>litter layer>herb layer>shrub layer,and the biomass of tree layer occupies a dominant position in the forest biomass.The biomass of tree layers of the four kinds of plantations is as follows:mixed forest>Quercus acutissima forest>Pinus densiflora forest>Robinia pseudoacacia forest.The overall relationship between the biomass of each organ of the tree is shown:the trunk>root>branch>leaves,and the trunk is the main part of the biomass of the tree.(3)The carbon density characteristics of four kinds of plantations in Huangqian watershed are different obviously.The forest carbon density of four kinds of plantations in Huangqian watershed is as follows:Quercus acutissima forest(230.86 t/hm~2),mixed forest(214.83 t/hm~2),Pinus densiflora forest(108.87 t/hm~2),Robinia pseudoacacia forest(102.20t/hm~2).The forest carbon dengsity of Quercus acutissima forest and mixed forest was significantly larger than Pinus densiflora forest and Robinia pseudoacacia forest.The carbon density of tree layer is as follows:mixed forest(154.79 t/hm~2),Quercus acutissima forest(128.08 t/hm~2),Pinus densiflora forest(61.02 t/hm~2),Robinia pseudoacacia forest(46.52t/hm~2).In terms of the carbon density of tree organs,carbon density of trunk is the main body of carbon density of tree,carbon density of roots and branches is the same,carbon density of leaves is at an absolute disadvantage.The carbon density of soil layer of four kinds of plantations is as follows:Quercus acutissima forest(99.23 t/hm~2),mixed forest(56.92 t/hm~2),Robinia pseudoacacia forest(53.89 t/hm~2),Pinus densiflora forest(45.32 t/hm~2).(4)The total forest carbon stock of four plantations in Huangqian watershed is511.47×103.The carbon stock of four plantations is as follows:Quercus acutissima forest(181.91×10~3 t),mixed forest(176.38×10~3 t),Robinia pseudoacacia forest(83.24×10~3 t),Pinus densiflora forest(69.94×10~3 t).The forest carbon stock both mixed forest and Quercus acutissima forest exceeded 34%of the total total forest carbon stock of four plantations,which are the main carbon pool in the four kinds of forest.The relationship of carbon stock of each layer is shown as tree layer>soil layer>litter layer>shrub layer>herb layer.The carbon stock of tree layer and soil layer respectively account for 59.65%and 38.70%of the total ecosystem carbon stock,which are the two main carbon pools in the forest ecosystem.(5)Forest structure of four plantations in Huangqian watershed has a significant effect on carbon sequestration function(carbon density).There is a good correlation between forest structure and carbon sequestration function.In four kinds of plantation,the forest density of four was significant positively correlated with carbon density of vegetation layer carbon density of soil layer and carbon density of the vegetation layer and forest carbon density.The DBH was significant positively correlated with density of soil layer and carbon density of the vegetation layer and forest carbon density.The forest height was significant positively correlated with density of soil layer and carbon density of the vegetation layer and forest carbon density.The uniform angle index was significant negatively correlated with the carbon density of soil layer,but it was little relationship with the carbon density of the vegetation layer and forest carbon density.The dominance was significant negatively correlated with the carbon density of vegetation layer,but it was little relationship with the carbon density of soil layer and forest carbon density.The mingling was significant positively correlation with carbon density of vegetation layer,but it was little relationship with carbon density of soil layer and forest carbon density.