Research On Carbon Storage And Distribution Pattern Of Three Artificial Forests In Fagaceae

Based on the 31-year-old plant species of Fagaceae in Guangxi,the biomass,productivity and carbon of the plantations of Castanopsis kawakamii,Castanopsis hystrix forest and their mixed forests in the southern subtropical region were studied.The distribution pattern of nitrogen reserves was studied.The biomass of each forest level in the plot was determined by the Monsic layered cutting method,the whole root excavation method and the sample square harvesting method.A regression model of different organs and total biomass of three forest layers was established using standard wood-related data.The elemental analyzer was used to determine the carbon and nitrogen contents of the vegetation and soil in each forest,and the total carbon and nitrogen reserves of different forest ecosystems were calculated.The relationship between the productivity and nutrient elements of the plantation ecosystem of Fagaceae area was studied.And the forestry density management of plantation carbon sinks provides a reference basis.Research indicates:(1)For the three different forest types of Castanopsis kawakamii forest,Castanopsis hystrix forest and their mixed forest,the fitting of the biomass of the individual tree species should be fitted by nonlinear equations.The data analysis results show that the shell The optimal equation for the biomass model of the Buckwheat tree plantation is W=a×Db×Hc,and the regression model of the root and the whole plant has the highest goodness of fit,and the goodness of the leaf biomass model is relatively poor.There is a strong positive linear relationship between the biomass of different organs in the three forest layers(the correlation coefficient R is between 0.8 and 0.9).Using the above nonlinear equations,the biomass of different organs in three different plantations was estimated as:180.78 t·hm-2 of Castanopsis kawakamii forest,193.28 t hm-2 of Castanopsis hystrix forest,and 207.59 t hm-2 of mixed forest.The biomass distribution patterns of the three plantations were:mixed forest>Castanopsis hystrix forest>Castanopsis kawakamii forest;arbor layer>litter layer>shrub layer;trunk>root>leaves>branches>bark>Fine root>coarse root>medium root.(2)The results of variance analysis of carbon density in three plantation ecosystems showed that there were significant differences in vegetation layer,litter layer,soil layer and ecosystem total carbon density in different plantations(P<0.01).There was also a significant difference between the carbon layers of each age group(P<0.01).The total carbon density of the ecosystem is:mixed forest(349.56 t·hm-2)>Castanopsis hystrix forest(219.7 t hm-2)>Castanopsis kawakamii forest(184.24 t hm-2).Soil carbon density dominated the total carbon density of the forest,and the average carbon density of the soil was 142.37 t hm-2.The average carbon density of the vegetation layer is 82.38 t·hm-2,and the average carbon density of the litter layer is 0.65 t·hm-2.The carbon density of soil layers between different forest stands is between 53.37 and 67.95%;the proportion of total carbon density of vegetation layer is between 31.79 and 46.38%;the proportion of carbon density of litter layer is 0.23-0.36.between.There is a negative correlation between vegetation density,soil layer and ecosystem carbon density and forest density,which is positively correlated with accumulation.Among the three stands,the carbon density of the mixed forest was large,and the carbon densities of the arbor layer of Castanopsis kawakamii,Castanopsis hystrix and mixed forests were 57.90 t·hm-2,100.75 t·hm-2 and 118.17 t·hm-2,respectively.The total carbon density of the three forest ecosystems gradually increased with the increase of forest age.The annual average carbon sequestration rate of the arbor layer is:mixed forest(1.20 t hm-2·a-1)>qingluo forest(1.09 t·hm-2·a-1)>Castanopsis hystrix forest(0.92 t·hm)-2·a-1).(3)Analysis of variance showed that there was a significant difference between the carbon sequestration rates of the three plantations(P<0.05),and the average annual carbon sequestration rate of the tree layer was mixed forest(1.20 t hm-2·a-1).Castanopsis hystrix forest(1.09 t·hm-2·a-1)>Castanopsis kawakamii(0.92 t·hm-2 a-1),the carbon fixation rate of mixed forest is 1.25 times that of Castanopsis kawakamii forest and Castanopsis hystrix forest respectively,1.14 times.The carbon sequestration rate of arbor layer increases with the increase of forest density and decreases with the increase of accumulation.(4)There are differences in the carbon sequestration potential and soil carbon sequestration potential of different forest stands.The carbon density-accumulation sequence of the ecosystem is established based on the carbon density of the Fagaceae ecosystem(initial value).Based on the sum of the maximum carbon densities of the carbon stocks,the carbon sequestration potential of the three plantation forest ecosystems was calculated.Three methods were used to estimate the carbon sequestration potential of forest vegetation:maximum value method,productivity model method and growth process method for variance analysis.The maximum value method and the growth process method have similar results for the carbon sequestration potential of different age groups,and there is no significant difference.P>0.05).The results of the carbon sequestration potential estimated by the productivity regression model method were significantly higher than those of the other two estimation methods,and there was a significant difference(P<0.01).The soil carbon sequestration potential ranges from 111.1 t·hm-2 to 129.82 t·hm-2.The soil carbon sequestration potential of the mixed forest was the highest,which was 129.82t·hm-2;the soil carbon sequestration potential of Castanopsisystrix forest was the lowest,which was 103.2t ·hm-2.The soil carbon sequestration potential of mixed forests was 1.25 times and 1.16 times higher than that of Castanopsis kawakamii forest and Castanopsis hystrix forest,respectively.