Research On Spatial Pattern Of Ecosystem Services In Nansihu Lake Basin Based On InVEST Model

As a research hotspot of ecosystem assessment,ecosystem service function plays a vital role in human survival and development and the ecosystem balance and continuation,and its quality directly influences the sustainable development of social economy.The development of GIS and RS technology for spatialization of ecosystem service has provided the powerful technical support.Based on the InVEST model,called the Integrated Valuation of Environment Services and Tradeoffs,and we simulated water yield?total nitrogen and phosphorus export and sediment yield in Nansi Lake Basin.We analyzed spatial distribution regularities and variation tendency about water yield,total nitrogen and phosphorus and sediment yield by using software of ArcGIS and discussed the the effect natural geographical elements(such as precipitation,topography)and economic factors(such as population,land use and gross domestic product)on the ecosystem service.The results showed that:(1)Water yield which showed a decreasing trend from east to west on spatial distribution pattern,was high in the east and northeast and relatively low in west and other regions in Nansi Lake Basin.Affected by natural geographical elements,the spatial distribution of water yield was not inconsistent with the spatial distribution of social economic development level,namely Gross Domestic Product and population.Water yield showed a decreasing trend of in the basin,and peak area of water yield transfered from the northeast to the south area,but low area transfered from the west to the central region in past 25 years.There were significantly positive correlations between variation of water yield and factors of physical geographical environment of precipitation,DEM,slope,and the correlation between precipitation and water yield was the most strong.There were significant positively correlations between variation of water yield and social economic factors of GDP and population.The main reason was that the development of urbanization and the increase of the impervious layer of urban construction land have promoted the water yield in the basin.(2)From 1990 to 2013,the export of total nitrogen and phosphorus change trend was not obvious and presented a rising tendency in an overall view in Nansi Lake Basin.There was significantly positive correlation between construction land and nutrient(total nitrogen and phosphorus)export,So the construction land promoted the nutrient export.There was significantly negative correlation between forest land and grassland and total nitrogen and phosphorus export.It indicated that the increased area of forest land and grassland inhibited the total nitrogen and total phosphorus export.So forest land and grassland played a vital important role in purifying water quality.The export of total nitrogen,total phosphorus had significantly positive correlation with rainfall,DEM and slope.In addition,the correlation analysis of nutrient(total nitrogen,total phosphorus)export with social economic factors(GDP and population)demonstrated there was significantly positive correlation with and total nitrogen and phosphorus.So these factors promoted the nutrient export.(3)In the research period,sediment export presented a decreasing trend as a whole.The correlation analysis of land use change with sediment export showed that there was significantly positive correlation between arable land with sediment export,so it promoted sediment export in the basin.Forest land and construction land had significantly negative correlation with export respectively,so they restrained sediment export.Due to the shrinking of forest land area from 1995 to 2000,it promoted sediment yield in the basin.The research results can provide scientific support for ecosystem services management and social and economic development planning and macro decision.