The Study On Carbon Sink Function Of Salix Gordejevii Plantation On Sand Of Semi-arid Region

Desertification is one of the world’s most serious environmental problems.In addition, the human activities cause global warming and climate change, it has become a hot issue which concerned by governments and scientists. Vegetation restoration measures are effective prevention and control of desertification. The carbon sequestration is one of the important ecosystem services of shrub plantation in arid sandy land.This paper took the Salix gordejevii plantation as the study object, which was in the typical shrub of sandy region in the southern margin of Khorchin Sandy land. Based on planting density, site conditions, plantation ages and cutting years, it analyzed the growth condition, carbon sink effect and the above-ground biomass of cut Salix gordejevii in different ages. It provided the basic data for evaluating ecological service function and experience for managing the high carbon sequestration shrub.We draw the following conclusions:1.The optimal over-ground biomass estimation model was a power function equation:y=2.193x’291 (R2=0.915, P<0.001).The fitting results checked by accuracy test (Rs<30%; RM.A<20%) was good,2.The optimal vegetation layer biomass estimation model equation was made by studying the Salixgordejevii plantation in different ages:y=-8.501x2+334.47x-812.61, R2=0.968. The vegetation layer biomass of Salix gordejevii plantation with different ages were mainly in the shrub layer, and the herbaceous layer comprised a relatively small part. Through the ecosystem carbon density analysis, it found that the carbon density of Salix gordejevii in different ages(2a-33a) show a trend which was increasing rapidly and then slowly and finally steadily.The equation was:y=-3.767x2+212.37x+294.59, R2=0.990.The carbon density of each ecosystem component ranked as:soil layer>shrub layer>herb layer>litter, the soil layer carbon density was account for more than 59.77% of total carbon density and the increasing was mainly on 0-20cm soil layer. The carbon density of herb layer and litter layer was less than 5%.3. The Salix gordejevii plantations of Different forest ages (13a,15a,18a,21a) were updated.It found cutting management was good to promote growth of branch and root. The number, length and diameter of branch was increasing as the age increasing after cutting. There was a significant difference among leaf length, width and aspect ratio. The leaf length was 8.11cm, the width was 5.39mm after cutting, while the leaf length was 5.84cm,the width was 2.65mm without cutting management.The shrub layer biomass and carbon density of Salix gordejevii in different ages were mainly concentrated on root system. The carbon density and biomass of 18-year-old Salix gordejevii whose cutting year was 5 years took account for the most.The above-ground biomass and carbon density was mainly on branch. The increasing speed was faster after cutting, and the proportion of total is increasing gradually. The growth rate of 21-year-old Salix gordejevii was the highest. The equation was y=28.24x1.642 R2=0.987. The root of 15-year-old Salix gordejevii increased most quickly. The growth rate of above-ground biomass and carbon density reach the maximum at the 4th year after cutting. To make the plantation develop steadily and healthily, cutting should be done again in five years later.