Dynamics Of Carbon Storage And Carbon Sequestration Potential Of Broad Leaved Forest Ecosystem In Hunan Province

Broad-leaved forest is an important component of forest in Hunan Province,and plays an important role in the process of carbon cycle and carbon balance of forest ecosystem in Hunan Province.Based on the vegetation inventory data(1983-1987 to 2014),investigation data of 6605 pieces of fixed sates of Hunan province in 2004,combined the data of shrub layer,herb layer,litter layer and soil layer of broad-leaved forest ecosystem that were published in recent 20 years.And combined measured data of litter layer and soil layer(0-80 cm)of broad-leaved forest in 2015,we estimated systematically the dynamic characteristics and regional spatial distribution pattern of carbon storage and carbon density of the broad-leaved forest ecosystem in Hunan province,estimated carbon sequestration potential of the tree layer of broad-leaved forest,and analyzed the change characteristics of ecosystem carbon sink and it provides scientific basis for understanding its role in the carbon cycle of forest ecosystem,it provides for improving the carbon sink function of forest ecosystem in Hunan Province,it also provides basis data for the accurate estimation of the carbon sink function of national scale or provincial and regional scale forest ecosystem.The main results of the research are as follows:(1)Each survey period,carbon storage of vegetation layers showed that the tree layer was the biggest,shrub layer and herb layer was the lowest.The proportion of vegetation carbon storage accounted for vegetation carbon storage of broad-leaved forest vegetation layer in the same period was on the rise,but the overall decline in the mature forest.The vegetation carbon density of each age-class showed a net decrease.The same survey period(except 2009),broad-leaved forest vegetation carbon density gradually increased with the increase of age.Except for 2014,the carbon storage of litter showed the highest young forest.Young forest,middle-aged forest and mature forest accounted for the same period in the province's broad-leaved forest litter layer of carbon reserved in the proportion of gradually rising trend,near mature forest is up-down-up,over mature forest decreased gradually.In every period,young forest,middle-aged forest,mature forest and over mature forest(except 2014)carbon density remained unchanged,the carbon density of near mature forest is different with other periods.The arithmetic average value of organic carbon in the soil of different age classes was between 15.19?27.00 g·kg-1,middle-aged forest's is the lowest,over mature forest's is the highest.In the 0-80cm soil layer,the arithmetic average value of soil organic carbon was between 12.42?27.98 g·kg-1,with the increase of soil depth,soil organic carbon content decreased.In the 0-80cm soil layer,the soil carbon density was between 145.61?232.83 tC·hm-2 in every age-class,the average value is 179.39 tC·hm-2,with the increase of age,it increased.It decreased with the increase of soil depth,the differences between different age groups also decreased with the soil of depth.In 1983-2014,soil organic carbon storage gradually increased.Young forest,middle-aged forest,near mature forest and mature forest,showed net increase,over mature forest is net decrease except 2014.The soil layer carbon storage of each age class and the proportion of soil carbon storage in the same period of were not consistent with the change of the time.In 1983-2014,carbon storage of broad-leaved forest ecosystem gradually increased,carbon density gradually decreased.Carbon storage and carbon density were as follows:soil layer>vegetation layer>litter layer.(2)In different investigation period,the spatial distribution pattern of forest ecosystem carbon storage is basically consistent in Hunan province.It showed that is higher in Southwest(Huaihua,Shaoyang),Sorth(Yongzhou,Chenzhou),Northwest(Xiangxi,Zhangjiajie)and Eastern(Zhuzhou),the second lower is in Dongting Lake plain of northern Hunan(Changde,Yiyang)and Eastern(Changsha),the lower is in Central Hilly Area of Hunan Province(Loudi,Hengyang,Xiangtan)and Dongting Lake plain of northern Hunan(Yueyang).The spatial distribution pattern of carbon density of broad-leaved forest ecosystem is also basically the same in Hunan province.All showed that Carbon density in Southwest(Huaihua,Shaoyang),Sorth(Yongzhou,Chenzhou),Northwest(Zhangjiajie)and Eastern(Zhuzhou)are obviously higher than the Central Hilly Area(Loudi,Hengyang,Xiangtan),Dongting Lake plain of northern Hunan(Changde,Yiyang,Yueyang),Eastem(Changsha)and northwestern(Xiangxi)in Hunan.(3)In 2014,The Real carbon sequestration potential of the tree layer of immature broad-leaved forest was 185.51 × 106 tC in Hunan Province.The Real carbon sequestration potential of tree layer of broad-leaved forest in different age classes followed that Young forest(1 00.81 × 106 tC)>Middle age forest(74.75 × 106 tC)>immature forest(9.96 × 106tC).The highest real carbon sequestration potential of the tree layer of immature broad-leaved forest in different cities of Hunan Province was Huaihua(35.50 × 106tC),the lowest is in Xiangtan(3.97×106tC).In 2014,the carbon sequestration potential of the tree layer of immature broad-leaved forest will be 88.08×106tC in Hunan Province.The potential of carbon sequestration of broad-leaved forest in different age classes is the middle age forest is the biggest,near mature forest is the second,young forest is the smallest.It showed that is higher in Southwest(Huaihua,Shaoyang),Sorth(Yongzhou,Chenzhou),Northwest(Xiangxi,Zhangjiajie)and Dongting Lake plain(Changde),the lower is Eastern(Zhuzhou,Changsha),Dongting Lake plain of northern Hunan(Yiyang,Yueyang),Central Hilly Area of Hunan Province(Loudi,Hengyang,Xiangtan).