| In the grand blueprint outlined in the 13 th five-year plan for national economic and social development of the People's Republic of China(2016-2020),it has become an important link for accelerating the improvement of the ecological environment,which has been fully integrated into all aspects and processes of economic,political,cultural and social construction.It is the only path to improve the quality and efficiency of social and economic development under the “new normal”.Meanwhile,the 13 th Five-Year Plan also proposes the important contents of promoting new-type urbanization,constructing modern infrastructure network,optimizing modern industrial system,and promoting the modernization of agriculture,which are both opportunities and challenges for ecological civilization construction.Enhancing the operation efficiency of society and market through "promoting new-type urbanization" and “constructing modern infrastructure network”,and guiding the development of agriculture and manufacturing industry transformed from factor-driven to innovation-driven through “optimizing modern industrial system” and “promoting agricultural modernization”,which are all feasible paths for efficient utilization of natural resources and reduction of environmental pollution,but at the same time,it is faced with some potetial risks such as environmental problems caused by pollutant discharge in the process of rapid urbanization,waste of land resources in the process of transportation infrastructure construction,excessive use of chemical fertilizers and pesticides in the process of agricultural modernization,and unreleasable overcapacity in the process of industrial transformation.How to avoid risks while seeking opportunities,which is critical to make the vision of the 13 th Five-Year Plan come true in China today.Driven by regional development strategies on national levels such as “The belt and road initiative”,“The construction of the Yangtze River Economic Zone”,and the “Triangle of Central China”,Hunan Province experiences a higher social and economic development rate than the national average and is an important region to undertake the transfer of population and industry in China.The abundant water and soil conditions in Dongting Lake and Xiangjiang River Basin have given Hunan Province renowned as “a land flowing with milk and honey”,undertaking the important task of safeguarding national food security;While the Wuling Mountain,Xuefeng Mountain,Luoxiao Mountain,and Nanling Mountain provide abundant resources for the locality,they are also important barriers to protect the ecological security in the middle reaches of the Yangtze River.Doting Lake Area administrated by Hunan Province is defined as a major grain producing areas and important national nature reserves at the same time,which has the obligation of grain production and environment protection.Ecological resources in Doting Lake area keeps shrinking under the influence of urbanization;As the core of Changsha-Zhuzhou-Xiangtan Urban Agglomeration,Changsha metropolitan area is the most urbanized and socio-economic developed area in Hunan Province,not only the population density and construction land keep growing,but also coming with more and more significant environmental issues.Ensuring coordination for socio-economic development and environmental protection is extremely important for achieving “Green Development” in Hunan Province,especially in Donting Lake area and Changsha metropolitan area,and provides references to different provinces,ecological functional areas,and urbans synchronously.Land ecosystem services is an important interface between human beings and nature,enhance land ecosystem services and protect it from degradation is highly conjuncted with the scientific conclusion that “Lucid waters and lush mountains are invaluable assets”,which is an effective shortcut towards comprehensive,coordinated and sustainable development.Based on all of the above,this dissertation takes Hunan Province as the main research object in the macroscopic level,supplemented by Dongting Lake region and Changsha metropolitan area as the typical research areas in mesoscale and microscale,and accomplished analysis of the evolution of land use pattern at different scales.By using InVEST model,the spatio-temporal evolution characteristics of land ecosystem services have been evaluated,the spatial and temporal response of land ecosystem services to land use pattern evolution has been analyzed,and the sensitive areas in the evolution process of land ecosystem services has been identified.On this basis,by constructing GWR model to detect the impact on land ecosystem services of urbanization,location conditions,economic development,and agricultural production,which have undergone drastic changes in recent 20 years,and it is proposed the optimization path of county land ecosystem services in Hunan Province.The coupling coordination model is applied to analyze the degree of land ecosystem services exerted by different gradient ecological lands,and the vertical management and control scheme of ecological land in Dongting Lake region is proposed to optimize and enhance land ecosystem services.By analyzing the difference of interference level for the urban expansion of different circles to land ecosystem services under different landscape patterns in,it is proposed the basic ideas of the future urban and rural planning in Changsha metropolitan area to minimize the damage of urban sprawl to land ecosystem services.The conclusions are mainly as following:(1)Analyzed the spatial and temporal evolution characteristics of land use intensity in counties of Hunan Province,a distribution pattern of ecological lands in Dongting Lake region,and urban expansion intensity in Changsha metropolitan area.From 1995 to 2015,it has shown an increasing trend for the average value of county land use intensity in Hunan Province,and land use intensity was the largest not only in economic developing areas but also the growth rate was significantly higher than that of the main agricultural production areas and ecological protection zones.The change of the main agricultural production areas was relatively stable,and land use intensity in ecological protecting areas remained on a low level relatively before 2010,but it there is a tendency of accelerating increase in recent years.Production and living spaces continuely sprawling and leads the ecological land become more concentrated in mountainous areas where economic development is relatively backward and geographical location conditions are relatively uncultivated.It has a great significance for saving valuable land resources and delaying the increase in land use intensity to protect the ecological environment.The distribution index of ecological lands in Dongting Lake region shows a “V” shape with the increase of terrain gradient.From 1995 to 2015,ecological land decreased in varying degrees on all gradients.Wetland and cultivated land kept exchanging in low gradient(1-5)water area,and there was a sharp decline of forest land in middle-high gradient(16-30),thus became the main characteristics of the evolution of ecological land distribution pattern in Dongting Lake region.The management and control of ecological lands in Dongting Lake region urgently needs to enhance from total amount of control to the vertical spatial distribution optimization.The basic urban form of Changsha metropolitan area is determined by the Third Ring Road.During 1995-2015,the scale of construction land expanded almost three times,the structure was gradually compacted,and land use intensity of in buffer No.1 to No.8 was significantly enhanced.However,the problem of extensive expansion of construction land in in buffer No.9 to No.15 areas and in buffer No.16 to No.20 still unsolved.The vicinity of the Third Ring Road needs to be focused on and prudential planned in the future.(2)Found out the characteristics of spatio-temporal evolution of land ecosystem services in Hunan Province,Dongting Lake region,and Changsha metropolitan area,and identified the sensitive areas of land ecosystem services in land use pattern evolution.It was obviously degraded for land ecosystem services in Hunan Province during the year of 1995 to 2015,with the greatest extent of degradation in the economic developing areas,and the expansion of construction land caused by rapid urbanization was the main reason.The change of land ecosystem services in the major agricultural production areas was relatively stable.Land ecosystem services in ecological protecting areas were first strengthened and then degraded.Mountainoues areas in the west and south were always characterized by low land use intensity and strong land ecosystem services.Land ecosystem services of Dongting Lake region and Changsha-Zhuzhou-Xiangtan urban agglomeration was obviously lower than that of the surrounding areas under higher land use intensity.Land ecosystem services of Changsha-Zhuzhou-Xiangtan urban agglomeration has greatly degenerated with the rapid increase of land use intensity,while land ecosystem services of Wuling Mountain and the upper reaches of Dongting Lake have been well maintained.Land ecosystem services in Dongting Lake region degraded during the year of 1995 to 2015,which mainly occurred in middle-high gradient(16-30).The main reason was the continuous spread of agricultural activities from lower gradients to higher gradients.The distribution of ecological land in medium-low gradient(6-15)and high gradient(31-50)was most closely related to land ecosystem services.Land ecosystem services were extremely sensitive to the change of the distribution of ecological land,while the sensitivity of low gradient(1-5)and middle-high gradient(16-30)was low.Under the effect of returning cultivated land to forests,lakes,and grasslands,the changed sensitivity of land ecosystem services to the distribution of ecological land for gradient 10-40 was decreased,while the sensitivity above gradient 40 was increased.Land ecosystem services in Changsha metropolitan area significantly degraded during the year of 1995 to 2015,with buffer No.5-15 being the most serious.The circle with low density of construction land and poor land ecosystem services gradually moves and expands from the center to the outside.The circle with a low density of construction land and strong land ecosystem services also shows the same change trend at the edge of the metropolitan area.The vicinity of the Third Ring Road will become the spot of further urban expansion and degradation of land ecosystem services in the future,while land ecosystem services on the edge of metropolitan area will gradually begin to be disturbed by urban expansion.(3)Revealed the differentiated impacts of urbanization,location conditions,economic development and agricultural production on land ecosystem servicess in different period and areas.Urbanization has a certain negative effect on land ecosystem services,and the intensity of urbanization became continuously weaken.The intensity of impact was obviously connected with the phase of urbanization.The higher level of urbanization,the smaller the overall negative effect.However,the extensive expansion of construction land in the period of rapid urbanization will lead to the aggravation of the negative effect.With the increasing attention paid to the protection of the urban ecological environment and the smooth shift of the employed population in mountainous areas to secondary and tertiary industries,urbanization may play a positive role in service of soil conservation.The improvement of location conditions has a stable negative effect on land ecosystem services,and the intensity was gradually weakening.The degree of land development and utilization in plain areas with flat terrain was generally higher than that in mountainous areas with steep terrain.Except for occupying ecological land itself,the road construction will also drive the expansion of construction land along the route,increase the intensity of human activities,interfere with land ecosystem services,and the negative effects of economic developing areas and the major agricultural production areas are stronger than those of ecological protection zones.The areas with the strongest negative effects are generally apperar at where railways and expressways are under construction.The impact of economic development on land ecosystem services was mainly positive and the degree of impact depends on the phase of economic growth.Promoting productivity,promoting industrial transformation,and improving the level of intensive land use are the main driving forces for positive effects,but it may have negative effects when industrial upgrading encounters bottlenecks.Agricultural production has a strong negative effect on land ecosystem services,which shows a spatial differentiation pattern of ecological protecting areas > major agricultural production areas > economic developing areas,but the intensity was gradually weakening from 1995 to 2015.The process of agricultural production was generally accompanied with the decline of vegetation cover caused by the conversion of forest land to cultivated land,the decline of canopy density of forest land caused by timber harvesting,the encroachment of overgrazing on grassland,and the destruction of water quality and aquatic species by transitional aquaculture and fishing.However,in the period of rapid urbanization,the ladder transformation of “Ecological Land?Cultivated Land?Construction Land” was the main reason for the weakening of land ecosystem services.(4)According to the specific situation of land use pattern and social and economic development level,it was proposed the optimization path of land ecosystem services in Hunan Province,Dongting Lake region,and Changsha metropolitan area.For Hunan Province: Firstly,enhance the quality of urbanization,strictly manage the allocation of construction land use rights in economically developed areas,improve the level of intensive land use,and protect ecological land use;Secondly,make a rational transportation networks construction plan,strengthen the connection between the eastern and western regions,increase the total sum of roads,improve the grade of current roads,and construct the traffic network based on knots of prefecture-level cities;Thirdly,promote economic transformation,obsolete manufacturing industries with high pollution and high energy consumption,support the development of innovative industries,and encourage the development of ecotourism industry in mountainous areas;Fourthly,develop high-quality modern agriculture,optimize the structure of agricultre,protect the dynamic equivalence of quantity and quality of cultivated land,make innovations in key agricultural technologies and actively respond to the strategic guidance of strengthening the foundation of agriculture in the no.1 central government document of 2019.For Dongting Lake region: Firstly,strictly control the reclamation of cultivated land in low gradient(1-5),ensure and improve the water storage capacity of Dongting Lake,reduce flood disasters,purify the water quality of Dongting Lake,and strengthen the protection and restoration of grassland and marshland along the lakeside;Secondly,guide the intensive and economical use of cultivated land and construction land in the middle-low gradients(6-15),and to control the reclamation of ecological land into cultivated land;Thirdly,to integrate cultivated land resources into areas with smaller slopes in the medium-high gradient(16-30),transform areas with larger slopes into woodlands,promote “double-low alternation”,vacate the scattered cultivated land and transform it into woodlands;Fourthly,in the high gradient(31-50),strictly control the development of forests into cultivated land and construction land,reasonably arrange timber harvesting,and promote the project of returning cultivated land to forestry.For Changsha metropolitan area: First is to transform the old residential areas in buffer No.1 to No.8,develop the potential capacity of underground space,improve the level of intensive use of construction land,restrict the utilization of land,and ensure low carbon and high efficiency in land use;Second is to strictly control the change of use of ecological land in buffer No.9 to No.15 to increase the proportion of commercial land and residential land in the general amount of construction land;Third is to control the total scale of construction land in buffer No.16 to No.20,guide the centralized distribution of industries,and pre-plan high-tech development zones;Fourth is to strictly manage the increase and circulation of rural construction land in buffer No.21 to No.25,and considerate forest parks into the further land use plan. |
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