| Land use change is the link between human activities and natural ecological processes,and it is also an important factor affecting the sustainable development of society and economy.At present,the coupling relationship among ecological environmentandsocio-economic effectsare mainly studied on cities and towns scale at home and abroad.There are few researches on the coupling coordination degree among the regional land ecological,social and economic effects on the pixel scale.The Loess Plateau in northern Shaanxi province is not only a hot spot area of land use change,and a vulnerable area of ecosystem,but also a key area of ecological construction,a key area of national energy construction and a key area of national poverty alleviation.In this study,the Loess Plateau in northern Shaanxi province,which is a multi-faceted ecological,social and human problem,was selected as the research area.Taking the sustainable development of land ecology,society and economy as the starting point,the land use,ecosystem service function,comprehensive effect of land use change and coupling coordination effect among land ecological,social and economicin the study area were quantitatively evaluated by using remote sensing interpretation,GIS spatial analysis and various mathematical models,thenthe temporal and spatial evolution law in multi-scale and multi-dimensional way were analyzed.In view of the main problems existing in the study area,the countermeasures optimizingthe sustainable use of regional land and the coordinated and sustainable development of land eco-social-economy were put forward.Therefore,this study has very important theoretical and practical significance for deepening the theory and method of regional human-land relationship,optimizing regional land resource management and promoting the coupling coordinated and sustainable development of land eco-social-economy.The main conclusions were as follows:(1)From 1991 to 2015,the overall land use degree of the Loess Plateau in northern Shaanxi province showed the spatial distribution characteristics of high in the Middle East and low in the south and north,and showed a fluctuating upward trend.Land use is in the development period as a whole,espetially with the acceleration of social and economic construction from 2007 to 201 5,the degree of land use showed an increasing trend.However,under the influence of the implementation of ecological construction project,the land use degree decreased the most or increased the least from 1999 to 2007.The decrease of cultivated land and the increase of forest land mainly occurred in the key period of ecological construction from 1999 to 2007,the decrease of unused land and the increase of grassland mainly occurred in the preparatory period of ecological construction from 1991 to 1999,while the increase of construction land and water land mainly occurred in the consolidation period of ecological construction from 2007 to 2015.The land use change on the Loess Plateau of northern Shaanxi province is significantly affected by terrain niche.The forest land increased in the high level terrain,but the unused land decreased in the low level terrain,and the repeated change of cultivated land and grassland was the most significant in the medium level terrain.(2)The ecosystem service function of forest land in the Loess Plateau of Northern Shaanxi province is the strongest,while the unused land is the weakest.From 1991 to 2015,the value per unit area of each ecosystem service function of different ecosystems were mainly rising,and the key rising period was the ecological construction period from 1999 to 2007.However,the value of organic matter production and carbon sequestration and oxygen release of construction land decreased,and the declining trend mainly occurred in the consolidation period of ecological construction from 2007 to 2015.In different ecosystems,the terrain effect of the ecosystem services value is significant.Among them,the dominant distribution range of the ecosystem services value in cultivated land is the widest,from the third to the 20th terrain level.That in forest land and grassland is the medium and high level(level 9-1 8).That in construction land and unused land is the medium andlowlevel(level 3-8).And the value in each terrain level is mainly increasing,which showed that the ecosystem service function of each terrain level on the Loess Plateau of northern Shaanxi province has improved.(3)From 1991 to 2015,the ecological effect,social effect economic effect and comprehensive effect of land use change in the Loess Plateau of Northern Shaanxi province were improved.Generally speaking,the change in the southern region was relatively weak,and the change in the central and northern region was more obvious.The comprehensive effect of forest land was relatively stable,and the comprehensive effectof cultivated land and grassland showed a fluctuating downward trend,while that of construction land and unused land showed a fluctuating upward trend.The comprehensive effect of land use on the Loess Plateau ofnorthern Shaanxi province showed a strong spatial agglomeration state in each period.However,due to the common influence of ecological governance and social and economic activities,the degree of agglomeration fluctuated greatly and generally weakened from 1991 to 2015,with the highest degree in 1999 and the lowest in 2015.The hot spot area was concentrated in the southern mountainous area,and the area has reduced.The cold spot area was mainly distributed in Hengshan County,Jiaxian County,Mizhi County and other central and eastern areas,and the area has increased.(4)The coupling coordination degree of land eco-social-economy on the Loess Plateau of northern Shaanxi province showed a slight increasing trend,but the growth rate was slow,and it was still in a medium imbalance state.On the pixel scale,the coupling coordination degree was basically randomly distributed,and there was no agglomeration effect.Thecoupling coordination degree was highest in Yushenfu energy zone,while lowest in the eastern and central agricultural district.The coupling and coordination degree of unused land,grassland and construction land is higher among 1991 and 2015,and ascending after the implementation of the policy of returning farmland to forest and grassland in 1999,while that of cultivated land and forest land,which overall increase,is lower and obviously decreasing after 1999.The coupling and coordination degree of land eco-social-economy in each county was characterized by fluctuation,with the largest change range in the key period of ecological construction from 1999 to 2007.And it could be summarized into four evolution types:stable,improved,degraded and fluctuating.In view of these four evolution types,this study proposes corresponding optimizing countermeasures to promote the coupling coordinated and sustainable development of regional land ecological,social and economic.The innovations and breakthroughs made in this study are as follows:(1)The terrain niche index is introduced to reveal the terrain niche effect and temporal and spatial evolution law of various ecological service functions of different ecosystems.This research breaks through the limitations of previous studies on administrative divisions,land use types and other horizontal dimensions,and integrates the terrain niche index into the study of the ecological effects of land use change,which is conducive to promoting the elevation,slope and other terrain factors in the vertical dimension to be included in the spatial control of regional ecological construction.(2)Combined with multi-source data,this research spatializes the social and economic statistics data into grid data,breaks the administrative boundary limit,and uses the grid mathematical model to calculate the comprehensive effect of land use change and the coupling coordination degree of land eco-social-economy which is conducive to a more detailed and in-depth analysis of the impact of land use change on ecology,society and economy,and can provide more accurate theoretical support to the coordinated and sustainable development of regional land eco-social-economy. |
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