| The function of ecosystem service is the basic guarantee of human survival and development.From the economic point of view,the analysis of regional ecosystem service function and its value provide a more accurate theoretical basis for regional ecological governance.The Loess Plateau is typical ecological fragile area in China.Through the longterm comprehensive management of soil and water loss,there were significant changes in land use types of regional ecosystem.This study took Shaanxi Wangdonggou watershed as study area,using land utilization comprehensive index of land use degree,dynamic degree of land use,land use change importance index,to analyzed the land use structure and changes from 1990 to 2015.Through the analysis of six kinds of main vegetation types on soil physical and chemical properties,assessment of vegetation types on soil quality was further compared.The 3S technique was included to estimate vegetation NPP,soil water storage,soil erosion intensity,and was also focused on the distribution of the southern basin topography fluctuation in the channel three with the slope and elevation terrain factor,and using the market value method,accounting for the total value of alternative engineering method carbon sequestration area of arable land,orchard,forest land and grass land,then releasing carbon fixation and oxygen,water conservation,soil and fertilizer conservation three kinds of ecosystem services.The results were as follows:(1)Land use types in northern tableland Wangdonggou watershed were mainly arable land,orchard and construction land,whereas the southern channel was dominated by forest land and grass land.Change of land use in 1990~2015 basin mainly included increasing area of forest land,grassland,orchard and construction land area and deceasing of arable area;among these,the orchard area was of the highest dynamic change.Overall,main change of land use was from arable land into the orchard.What's more,the comprehensive index of land use degree decreased,indicating that land use intensity was alleviated.(2)The soil physical and chemical properties varied greatly among different vegetation types in the watershed.Under the influence of artificial fertilization and irrigation,arable land and orchard factors,soil moisture,nutrient content,organic carbon density were generally higher than that of arbor forest,shrub land and grass land.Arbor forest land had higher soil nutrient content,indiciting the soil and fertilizer was higher;compared with the soil nutrient content in 1993,2002,2015,the soil of various vegetation types of organic matter,total nitrogen and available potassium content increased,with the increase of vegetation restoration years,soil quality was gradually improving.(3)We used CASA model to estimate the results of NPP,the result showed that the total amount of NPP of four land use types in this watershed was 2996.91 tons.In the channel,NPP of different slope of the average performance was semi shady slope > shady slope > sunny slope > semi sunny slope;increasing with altitude and slope,NPP gradually decreased.(4)The result of water storage which was estimated by water storage capacity method showed that,in four land use soil total water storage type was 134.20 tons,storage capacity of northern arable land and orchard was generally higher than that of the south channel region,mean of channel soil water storage in different slope was semi shady slope > sunny slope > shady slope >semi sunny slope;increasing with altitude and slope,water storage decreased.(5)The RUSLE formula was used to estimate the amount of soil erosion and conservation in the watershed.The results showed that the soil erosion in the watershed was in the total amount of 3416.96 tons and the soil conservation was in the amount of 56467.81 tons.In channel,soil erosion intensity was slight,and the mean of soil erosion intensity in different slope of performance for shady slope > semi shady slope > sunny slope > semi sunny slope;increasing with altitude and slope,soil erosion intensity showed a rising trend.(6)Using the market value method and substitute engineering method to explore the ecosystem service function value of arable land,orchard,grass land and forest land in 2015,we found that under different land use,the performance of carbon fixation and oxygen release of unit area was arable land > orchard > forest land >grass land;water conservation was orchard > arable land >grass land > forest land;and soil conservation was forest land > grass land > arable land > orchard.Carbon fixation and oxygen release value of forest land,grass land,arable land and orchard were 109.01?37.18?194.51?175.79 ten thousands yuan;water conservation value were 16.68?6.11?33.00?34.12 ten thousands yuan;and soil and fertilizer conservation value were 1603.59?543.41?223.53?179.26 ten thousands yuan;3165.19 ten thousands yuan in total. |
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