| The effect of soil and water conservation is to prevent and control the loss of soil and water,then to protect,improve and rational using the soil and water resources,to achieve the purpose of maintenance and raise the land productivity,in turn,established a favorable ecological environment,there more,conducive help ecological benefits,economic benefits and social benefits from water and soil resources to play a part effectively.With the development of soil and water conservation science and national attention to the territorial treatment and environmental protection,it is apparently important to actively carry out the work about the calculation and evaluation of ecological benefits of soil and water conservation.Therefore,calculating and evaluating the ecological benefits of soil and water conservation has become one of the key contents of the research about soil and water conservation science.Guiyang is known as the“forest city”,Government departments are fully constructing ecological civilization,striving for entering the national ecological civilization demonstration city ranks early,building a green ecological barrier tightly.How to construct ecological civilization reasonably,how to evaluate and analysis reasonably the achievements of establishment about ecological civilization.There are significant work.This paper from the perspective of urban green space,synthetically used the theory of soil and water conservation efficiency,the theory of ecosystem services,the theory of landscape ecology and remote sensing and geographic information system technologies,carried out the research about calculating and evaluating of urban green space's ecological benefits of soil and water conservation.This paper take Guiyang City,Guanshanhu District as the study area,divided the types of urban green space firstly,then extracted the green space information in the study area based on the data of remote sensing image,afterwards,estimated the ecological benefits of soil and water conservation from green space in the study area based on the theory of ecological services,and estimated its soil erosion amount through method called classification criteria of soilerosion,what's more,analyzed the change of spatial pattern of green space in the study area from1995 to 2016 on the basis of the green space landscape spatial pattern.Finally,explored the change of soil erosion and the change of spatial pattern of green space influence on the ecological benefits of soil and water conservation in the study area,which is aimed at providing basic datum for the construction of ecological civilization in the study area.The main research conclusions in this paper are as follows:(1)Changes in structure and spatial layout of green space: From 1995 to 2016,the area of the green space system in Guanshanhu District has net increased by 4127hm2,the proportion of the total area of the study area has increased from initial 57.56% to eventual 71.14%.In the green space system,the area of forest land has continued to reduce,the average annual loss rate was1.9%;the area of shrubby-grass land,cultivated land and wet land were increased in varying degrees,the average annual growth rate were 2.43%,3.34%,7.83% respectively.Accounts for the proportion of green space system in the study area,forest land has decreased only,shrubby-grass land and cultivated land has increased as a whole,wetland has increased continuously.In the transfer of land-use types,there were frequently roll-in and roll-out between green space system with the other space system.Thereinto,the governance of bare land,the transfer from forest land to shrubby-grass land,moreover,the transfer between shrubby-grass land and cultivated land with construction land,all urged that the structure of land-use types changed greatly in the study area.In addition,Guanshanhu District's degree of landscape fragmentation was on the high side overall,among them,the highest is forest land,the lowest is wet land.Shrubby-grass land,in the 21 years,always maintained in the position of the dominant landscape,the dominance of forest land has weakened gradually.Taking everything into consideration,the green space landscape layout has gradually diversified in the study area,the heterogeneity had enhanced slightly,and the proportion of each class types has developed to homogenize.(2)Changes in soil erosion: In the 21 years,soil erosion in study area was effectively contained,soil erosion amount has reduced,the descent range was 9.49%,and soil erosion amount was the lowest in 2005.The most obvious change in soil erosion is the western region in study area from 1995 to 2016.The continued decrease in area of forest land led to a decline in vegetation coverage in the western region,the ecological function of soil conservation was weakened.Therefore,there is a situation that a few intensification of soil erosion in the western region,it leads to the inversion of soil erosion amount and modulus in 2016.(3)Ecological benefits value of soil and water conservation in green space: the totle value of ecological benefit from green space in Guanshanhu District has net increased by 163.7792 million yuan,rate of increase attained 27.20%;the value of ecological benefits in per unit area of the green space presented a trend that reduced first and then recovery increased,to 2016,the ecological benefits in per unit of the green space attained 3.54 ten thousand yuan per hm2,in the21 years,it has net increased by 0.1 ten thousand yuan per hm2,rate of increase attained 2.91%.Thereinto,the largest contribution to the ecological benefits of soil and water conservation in green space of the study area is forest ecosystem,however,it showed a trend of gradual decline in the 21 years;waste disposal,maintain soil,climate and hydrology regulating was which could produce higher efficiency in various service projects.(4)Spatial and temporal patterns of green space and soil erosion influence on ecological benefits of soil and water conservation: the biggest impact to the ecological benefits of soil and water conservation in Guanshanhu District's green space is wetlands ecosystem,the second is forest ecosystem.From 1995 to 2005,the reasons that the value of ecological benefits in per unit area from green space in study area has reduced,on the one hand is area of forest land has declined sharply and area of shrubby-grass land has increased swift,on the other hand,as a result of the unbalance of green space landscape layout.During the period,landscape heterogeneity has declined,although the adjacency degree has increased.From 2005 to 2016,the value of ecological benefits in per unit area from green space in study area has recovery increased,since land-use has developed intensively,the structure of green space tends to equilibrium,another aspect,owing to the diversity and heterogeneity of green space landscape layout has increased.Between SHDI and SHEI with the value of ecological benefits in per unit area from green space were positively correlated.In the 21 years,the variation of soil erosion amount in the study area is consistent with the variation trend of the ecological benefits total value of soil and water conservation.That is to say,the more severe of soil erosion,the lower of ecological benefits value of soil and water conservation.Besides,changes in soil erosion have a greater impact on conservation soil and maintaining biodiversity. |
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