| In recent years,the Loess Plateau has carried out a large-scale construction in ecological management,which has brought series of changes in the structures of land use and the ecological environment.Under this social background,the study of ecological function of small watershed has attracted more and more attention.In order to solve the ecological problems such as severe vegetation destruction,lacking of water resources and extreme climates in the loess hilly and gully region,it is an important task to accelerate vegetation restoration and construction for this area.In this paper,the Miaogou watershed-atypical representative of the loess hilly and gully region was taken as the research object,using remote sensing(RS)and geographic information system(GIS)technology,geostatistics and mathematical statistics model specially,combining field investigation and experiment and indoor chemical analysis,applying DEM and remote sensing images(RS)to ensure the function's changes,such as the changes of land use in Miaogou basin,and the function of water,soil and fertilizer conservation,carbon fixation and oxygen release.What's more,the value of ecosystem function in the basin at different periods was estimated to provide a reference for agricultural ecosystem management in arid areas.The main conclusions were as follows:(1)Forest land is the main land use type.Grassland,cultivated land and garden area are flat,the scale of grassland and forest land are widely distributed,and the distribution of cultivated land is relatively concentrated.In 2005,the distribution area of forest land was the largest,which was 3.62 km2,accounting for 45.42% of the total area.The distribution area of grassland,cultivated land and garden land respectively was 1.50 km2,1.39 km2,1.03 km2.Specially woodland area increased by 110.47% in 2000-2015,and orchard area decreased by 61.99%.During the study period,the area of forest land increased significantly,which mainly caused by the inflow of the area of the garden area and grassland area.The area of the garden was mainly transferred into the forest land and farmland.(2)The value of water conservation in the per unit area was shown obviously in the study area,that is,the value of water conservation value of unit surface was increasing in the whole of the northern,middle and southern areas of the Miaogou basinis.The water storage capacity of forest land was the strongest,and its water storage volume accounted for 45.94% in the total water storage volume of each area.The value of water conservation was 15.87 million yuan.During the period from 2000 to 2015,the value of water conservation in the other types of land use were increasing in addition to garden(-48.32%),and the increase of forest land(213.64%)was the largest.(3)The amount of soil was mainly distributed in the central and southern fringe,and the central region less soil.The amount of soil in the forest land was the highest,which was 34589.33 t,accounting for 51.48% and the corresponding value of solid soil was 338,100 yuan.Fertility value has such as orders: forest land(906.32 million yuan)> grassland(341.02 million yuan)> cultivated land(212.51 million yuan)> garden(211.41 million yuan)> construction land(40.99 million yuan).The highest value of solid soil fertilizers was forest land(940.13 million yuan)in the Miaogou basin in 2015,accounting for 52.88% in the total area of soil and soil fertility value,and grassland(354.05 million yuan),accounting for 19.91%.Compared with the value of land-fixation and soil fertility in 2000,the change degree of forest land and garden land was higher in the study period,but the forest land showed a higher growth trend(79.86%),and the garden showed a sharp decline in value(72.00%).(4)The value of carbon and oxygen in unit area was high in the southwest edge of the area,and the value of the distribution area along the valley was lower.The total value of carbon sequestration and oxygen release was RMB 3,602,200 in the whole region in 2015,of which the total value of carbon sequestration and oxygen release in forest land exceeded half of the total value of the whole region,accounting for 52.96%.The total value of carbon sequestration and oxygen release increased by 66.87% in 2015 compared with that in 2000,and the main contribution was from woodland.The value of carbon sequestration and oxygen release in forest land increased by 286.77%. |
PDF Full Text Request