| As an important component of Qinghai province in Qilian Mountain National Park,headwater region of Heihe River is an important water-supply area and a natural green barrier in the arid area of the northwestern inland,but also an ecological sensitive and vulnerable area.With the scientific argument that“lucid waters and lush mountains are invaluable assets”,the problems on ecological protection and environmental governance in the headwater region of Heihe River become even more urgent.Soil,the most important component in ecosystem,can not only directly reflect the impact of natural factors and human factors on ecosystems,but also is the most important water storage and regulator in the regional environment.Thus,clarifying the soil carbon and water storage capacities and their potentials in the headwater region of Heihe River is not only critical for improving the carbon sink potential,but also plays an important role in maintaining the ecological environment safety,which it may provide theoretical reference to the ecological environment protection in this region.The headwater region of Heihe River as the subject,this study researched its capacity of soil carbon and water storage and potentials based on field survey data and remote sensing data,got to known the status of land use,vegetation cover,and soil physical property,grasped the characteristics of soil carbon and water storage capacity,determined dominant factors influencing the capacity of soil carbon and water storage.On this basis,this study also quantified the capacity of soil carbon and water storage in main ecosystems,predicted the capacity of soil carbon and water storage in 2030year under the scenario of which soil carbon and water storage would maintain at current level and land use pattern occur to vary as well as finally discussed potentials of carbon and water storage in the study area.The results could provide basic data and reference for the sustainable development of the ecological environment and construction of the Qilian Mountain National Park.The main conclusions are as follows:(1)In the past 15 years,the vegetation coverage of the study area has gradually increased from northwest to southeast,and the increase area accounts for 50.58%of the study area.The land use types in the study area are mainly grassland,glaciers/naked rocks and forest land,accounting for more than 90%of the area of the study area,after calculating the comprehensive dynamic degree of land use,it is found that the intensity of land use change in the study area is relatively small in the past 15 years;in all ecosystems,except for the grassland soil texture is sand-silver soil level,the rest of the ecology the soil texture of the system is silt-sand soil level;the soil bulk density of each ecological type increases with the increase of soil depth,and the total soil porosity decreases with the depth of the soil layer.(2)The soil carbon storage capacity generally decreases with the increase of soil layers.(1)In the grassland ecosystem,the carbon storage capacity of each grassland type per unit mass and unit area are in the same order,which is expressed as wetland>alpine grassland>alpine meadow>alpine marsh;(2)in the forest land ecosystem,the carbon storage capacity of the mass and area of Picea crassifolia is greater than that of Cyoress Qilian;(3)in the shrub ecosystem,the carbon storage capacity of each shrub type per unit mass and unit area are in the same order,which is expressed as mixed shrub>Caragana jubata shrub>Potentilla fruticosa shrub.(4)Among the ecosystems,the soil carbon storage capacity per unit mass and unit area showed wetland>forest land>shrub>grassland>cultivated land.(5)The changes of soil bulk density,mass water content of soil,soil total porosity,NDVI,elevation and slope direction in 0~20 cm soil layer are the dominant factors affecting soil carbon storage capacity,which explained 66%;The changes of mass water content of soil,soil silt content,slope and NDVI in the 30~50 cm soil layer are the dominant factors affecting soil carbon storage capacity,which explained 62.80%.(3)The actual water storage capacity of the soil is not much different within the depth of the soil layer,and the soil saturated water storage capacity decreases with the increase of the soil layer.(1)In the grassland ecosystem,the actual water storage capacity of the soil is in the order of wetland>alpine marsh>alpine meadow>alpine grassland;the order of soil saturated water storage capacity is wetland>alpine marsh>alpine grassland>alpine meadow;(2)in the forest land ecosystem,the actual water storage capacity and saturated water storage capacity of the Picea crassifolia are stronger than that of Cyoress Qilian;(3)in the shrub ecosystem,the actual water storage capacity and saturated water storage capacity were opposite,and the former expressed as mixed shrub>caragana jubata shrub>potentilla fruticosa shrub.(4)Among different ecosystems,the order of soil actual water storage capacity is wetland>shrub>grassland>forest land>cultivated land,and the order of soil saturated water storage capacity is forest land>wetland>shrub>grassland>cultivated land.(5)Soil bulk density,mass water content of soil,slope and slope direction in0~20 cm soil layer are the dominant factors affecting soil water storage capacity,which explained 89.1%.Soil bulk density,mass water content of soil,average grain size,elevation,soil sand,soil silt,slope direction and NDVI were the dominant factors affecting soil saturated water storage in the 30~50 cm soil layer,which explained 69.1%.(4)The spatial distribution of soil carbon storage capacity and water storage capacity in the study area is relatively uniform,showing a distribution pattern that gradually increases from northwest to southeast.(1)In 2015,the soil carbon storage in0~50 cm soil layers of different ecosystems was in the order of grassland(1.10?10~8t)>shrub(2.83?10~7 t)>marsh wetland(6.27?10~6 t)>forest land(4.23?10~6t)>cultivated land(1.26?10~6 t)>bare land(2.18?10~5 t)>artificial land(1.57?10~5 t),under the scenario that the soil carbon storage is the current estimate,the soil organic carbon storage in grassland and bare soil will be reduced by 9.41?10~6 t and 6.49?10~2 t by 2030,respectively.Soil organic carbon storage in cultivated land,shrubs,forest lands,artificial land and marsh wetlands will increase by 2.04?10~4 t,5.64?10~6 t,7.06?10~5 t,3.06?10~4 t,6.22?10~5 t,respectively.(2)In 2015,the soil water storage reserves of 0~50 cm soil layers in different ecosystems were in the order of grassland(17.27?10~8 t)>shrub(4.63?10~8 t)>marsh wetland(8.70?10~7 t)>forest land(5.80?10~7t)>cultivated land(1.60?10~7 t)>bare land(3.50?10~6 t)>artificial land(2.14?10~6 t),under the scenario where the soil water storage reserve is the current estimate,the grassland and bare soil water storage reserves will be reduced by 1.38?10~8 t and3.12?10~4 t by 2030,respectively.The soil water storage reserves of cultivated land,shrub,forest land,artificial land and marsh wetland will increase by 2.14?10~5 t,8.10?10~7 t,8.99?10~6 t,4.57?10~5 t,8.88?10~6 t,respectively.(5)Under the prediction of this study,shrubs,forest lands and wetlands in each ecosystem have the highest carbon storage potential,while grassland is the largest ecosystem in the study area.Under this scenario,grassland soil carbon storage capacity will be significantly reduced and reduced much more than other ecosystems by 2030. |
