Research On The Dynamic Evaluation And Change Of Ecosystem Service Value In Loess Plateau

Ecosystem service value is the value quantification method of ecosystem service function.The level of value not only reflects the status of regional ecological environment,but also indicates whether the land use method is reasonable.Studying the feedback mechanism between ecosystem service value and land use change can find a balance point for economic development and ecological environment protection and realize sustainable development of regional economy.Chinese terrestrial ecosystem service value equivalent was proposed in 2001.The value equivalent table is for the average level in mainland China.The value equivalent is for the average level of the Chinese mainland.When it is applied to the evaluation of regional ecosystem service value,there are two problems.One is that the ecosystem service value is different due to the obvious differences in the internal structure and external shape of the same type of ecosystem in different regions.When the value equivalence table is applied to different regions,its accuracy is uncertain.The other is that due to changes in socio-economic development and people's willingness to pay for ecosystem services,it is not rigorous to use the 2001 value equivalent to measure ecosystem service values in different years.Therefore,based on the value equivalent,considering that ecosystem services vary in different time and different space,ecosystem service evaluation model was improved in time and space scale in this paper to reduce the value-equivalent change due to social development,changes in resource scarcity and value equivalent changes of the same ecosystem located in different geographical locations.The spatial heterogeneity correction firstly uses the grain output as the basis to achieve the correction of the value equivalent from the national to the regional scale and then uses the vegetation coverage and NPP as indicators to achieve the correction of the value equivalent from the area to the grid scale.The social development coefficient was revised with Engel coefficient,GDP and urbanization rate.Resource scarcity coefficient was corrected by population density index.Calculate the value of a standard unit-equivalent factor by using net food profits in 2005 as a constant price.Because the value equivalent does not take into account the value of settlement ecosystem services,this paper separately calculates the value of the settlement's services.After the spatial heterogeneity correction,social development coefficient correction,resource scarcity coefficient revision and determination of the unit area value of ecosystem service functions,the Loess Plateau ecosystem service value dynamic evaluation model equivalent was correctted.Thus the accuracy of ecosystem services valuation could be improved.Increase the comparability of ecosystem service value in 2000,2005 and 2010.Based on the corrected Loess Plateau ecosystem service value dynamic evaluation model,we can analyze the ecosystem service value change characteristics in time and space scale.The total value of loess plateau was 633.391 billion,767.995billion and 939.046 billion in 2000,2005 and 2010.The total value increased 48%from 2000 to 2010.The value of soil conservation which is provided nearly 80%by forest and grassland is the highest of all the ecosystem services value.Therefore,to promote the conversion of desert to grassland and forest land,and to use the soil-solidification capacity of vegetation to reduce desert soil loss is the key to the control of soil erosion in the Loess Plateau is to promote the conversion of desert to grassland and forest land,and to use the soil-solidification capacity of vegetation to reduce desert soil loss.From 2000 to 2005,the increase of forest ecosystem service value and grassland ecosystem service value in Loess Plateau accounted for about 70%of the total increase in service value.From 2005 to 2010,the ecological service value of Loess Plateau continued to increase,with an increase of approximately 40%in service value contributed by grassland,and the benefits of returning farmland to grassland ecological projects were significant.If we analyze the ecosystem service value in space scale,we can find that the overall trend of ecosystem service value in Loess Plateau is high in the southeast and low in the northwest.The areas with the highest value of ecosystem services were distributed in river water systems;the fastest growing value of ecosystem services was the Inner Mongolia Autonomous Region.There were two reasons for the increase of ecosystem service value,one is the contribution of ecological protection measures,such as returning farmland to forest and grassland,sanbei shelter forest.The other is human pay more attention to ecological environment.During the period 2000-2005,the total land use change in the Loess Plateau was approximately 11046.86 km~2,accounting for approximately 1.8%of the total area of the Loess Plateau.The arable land is mainly converted to grassland and forest land.and grassland is the main source of new arable land.The net increase in forest land is 2205.41 km~2 which was mainly converted by cultivated land and grassland.The net increase in unused land area was 1,487.02 km~2,of which the increase in sand area accounted for 69%,indicating that the desertification of the Loess Plateau was still very serious from 2000 to 2005.From 2005 to 2010,the arable land continued to decrease,which mainly changed into urban and rural industrial and mining residents'land,forest land and grassland.The net reduction in unused land area was about790.29 km~2 and mainly converted to grassland and arable land.Managing uncultivated land does not only improve the ecological environment of the Loess Plateau,but also improves the utilization of cultivated land reserve resources.In order to study the importance of land use change to the ecosystem service value,the ecosystem service value change rate of all land use types in the Loess Plateau in 2005 and 2010 was calculated.2000-2005,the greatest ecosystem service value change rate was urban and rural industrial and residents land.The 8.9%change in the area of urban and rural industrial and residents land led to a 102%change in its ecosystem service value.Next was forest and grassland.Increasing the area of forest lands and grasslands and improving the quality of forest lands and grasslands were of crucial importance to the environmental protection of the Loess Plateau.2005-2010,the greatest ecosystem service value change rate was grassland.The 0.8%change in the area of grassland led to a 24.3%change in its ecosystem service value.On the one hand,the unit value of grassland had been greatly increased.On the other hand,thanks to the increase in people's awareness of environmental protection,the quality of grassland ecosystems had improved.The environmental economic coordination function was established to analyze the degree of coordination between economic development and ecological environment in the Loess Plateau.The environmental and economic coordination index of the Loess Plateau during the period from 2000 to 2010 was 0.1153,which was at a low level of coordination.It showed that the growth rate of the ecosystem service value was lower than the GDP growth rate.The economic development had not caused damage to the ecological environment,but there was a potential crisis in the stability of the ecosystem.Environmental-economy coordination index for2005-2010 was reduced by 11.3%compared with 2000-2005.On the one hand,the afforestation speed of the Loess Plateau in the early period was faster than that of the later period,which made the growth rate of the ecosystem service value smaller.On the other hand,with the development of the western region,the socio-economic development speeded up.Among the 7 provinces,the higest environmental economic coordination is in ningxia.On the one hand,the Yellow River runs through Ningxia from south to north,and the area of irrigated land in the north of Ningxia is larger.Reasonable irrigation in farmland and the improvement of grassland quality made ecosystem services increased.On the other hand,the economic development of the Ningxia region is slower than the other 6 provinces,and the greatly increased ecosystem service value made its environmental and economic coordination index relatively high.