Evaluation of forest ecosystem carbon fixation and oxygen release services in Shaanxi Province from 1999 to 2003
1999—2003年陕西省森林生态系统固碳释氧服务功能价值评估

From 1999 to 2003,the estimated carbon fixation per year was 526.4×10 t in northern Shaanxi,with 1404.6×10~4t oxygen released per year.The values were equivalent to 1.364t/ (hm~2·a) carbon fixation per unit area per year and 3.652t/ (hm~2·a) oxygen released per unit area per year.Equivalent numbers for the south were 1797×10~4 t C,5918.9×10~4t O_2,3.459t/ (hm~2·a) C and 9.26 t/ (hm~2·a) O_2.C fixation value per year in Shaanxi forests is 328.27×10~8 Yuan,oxygen released per year is 732.35×108 Yuan and total value is 1060.62×10~8 Yuan.Long-term and continuous observations of forest ecosystems were used in the survey.Data was taken from the sixth Shaanxi Province forest resources inventory,which showed a huge difference between the southern and northern climates of Shaanxi Province.Actual productivities in the different climatic zones of Shaanxi Province were used to estimate forest ecosystem carbon fixation and oxygen release services.These values were estimated by applying the method of market value,the method of substitution of expenses,the law of shadow project and the method of volume-derived biomass.Ecological functions in southern Shaanxi were clearly better than in the north.The forest stands had the highest value and function while the woodlands had the lowest.The total value of forest ecosystem C and O_2 services per year in Shaanxi Province was estimated at 1060 ×10~8 Yuan.More in-depth and detailed studies appeared necessary because the estimated carbon fixation and oxygen release values for dominant species were not classified by stand age.