Research On The Characteristics,Effects And Simulation Of Urban Construction Land Expansion

Since the reform and opening-up policy,China's industrialization and urbanization have been rapidly promoted,and the scale of urban construction land has expanded rapidly.Urban construction land is an important carrier of human life and production activities.The expansion of urban construction land is beneficial to meet the needs of regional social and economic development,but also directly lead to the rapid change of regional landscape pattern,which will inevitably have an important impact on the ecological process.Unreasonable urban construction land expansion will inevitably lead to the non-healthy evolution of landscape pattern,which poses a threat to ecological security.Therefore,the researches of urban construction land expansion characteristics,the analysis of the effect of urban construction land expansion on landscape pattern,and the simulation of urban construction land based on landscape safety protection are of great significance to maintaining the function of the landscape and ensuring the sustainable development of the region.Scholars have done a lot of research on the expansion of urban construction land and the change of landscape pattern.However,there are few studies on the change of landscape pattern caused by the expansion of urban construction land.Most of the existing researches are about the changes of regional landscape pattern under the background of urbanization,city sprawl,urban construction land expansion and land use change,which lack the landscape pattern effect and simulation research of the expansion of urban construction land.Yangzhou is located in the middle of Jiangsu Province,the North Bank of the lower reaches of the Yangtze River and the southern end of the Jianghuai plain.It is located between 32° 15' N to 33° 25' N,and 1190 01' E to119° 54' E.Yangzhou has a superior natural environment,which is the city of Nanjing metropolitan area and the Yangtze River Delta city group,and is also a typical ecotype city of the eastern part of China.As the most vital node city in the economic circle of the Yangtze River Delta in China,the social and economic development of Yangzhou is rapid,and the expansion of urban construction land is very rapid.The expansion of urban construction land occupied a large number of production service and ecological service landscape,resulting in the rapid change in the regional landscape pattern,and the ecological process changed accordingly.Under the background of the planning requirements of "multi-compliance",the multi-objective conflict of the social and economic development and ecological protection in Yangzhou is obvious.Therefore,taking Yangzhou of Jiangsu Province as an example,this paper builds the research framework based on the "Driving force-Pressure-State-Impact-Response"(DPSIR)model.The external driving force and pressure make the urban construction land state change as indirect and direct form,and then influence the regional landscape pattern.In order to avoid the negative impact of urban construction land expansion on the regional landscape pattern,the response of optimizing the allocation of new urban construction land should be made.Based on the path analysis,this paper identifies the driving force and pressure factors that affect the expansion of urban construction land from the perspective of supply and demand.From the two aspects of internal and external analysis,the characteristics of urban construction land expansion are analyzed.The internal characteristics of urban construction land expansion are analyzed based on the landscape pattern index.The external characteristics of urban construction land expansion are studied from aspects of scale,intensity and direction.By means of transfer matrix,regression analysis and gradient analysis,the influence of extension scale,expansion intensity and expansion direction of urban construction land on regional landscape pattern is studied in this paper.The ANN-CA model is applied to simulate the urban construction land allocation plan under different landscape safety level scenarios combined with constructing the regional landscape security pattern,so as to protect the regional landscape ecological safety.This paper draws the following conclusions:(1)The results of the analysis of influencing factors of urban construction land shows that the factors affecting the expansion of urban construction land are the endowment characteristic,the distance to the center of the city,the traffic condition,the technical level,the policy system,the economic development,the population growth.Among them,the direct path coefficient of the distance to the center of the city,the traffic condition,economic development and population growth is larger than its indirect diameter coefficient,which are the direct influence factors.The indirect coefficient of the characteristics of the endowment,the technical level and the policy system are larger than the direct diameter coefficient,which are the indirect influence factors..The endowment characteristic directly??promotes the expansion of the urban construction land,but through the distance to the center of the city,traffic condition,population growth and other intermediary variables indirectly inhibit the expansion of urban construction land.The technical level directly inhibited the expansion of urban construction land,but the distance to the center of the city,traffic condition,population growth promote the expansion of urban construction land indirectly as an intermediary of the technical level.The policy system promotes the expansion of urban construction land directly and indirectly,mainly through the distance to the center of the city,traffic condition,economic development,population growth and other intermediary variables to promote the expansion of urban construction land indirectly.(2)The analysis of the internal characteristics of the expansion of urban construction land shows that the fragmentation of the urban construction land in Yangzhou is gradually reduced,the connectivity is increased,and the shape is more and more regular in the 2005-2013 years.There are obvious differences in the landscape pattern change of urban construction land in each district(county and city).The fragmentation of the urban construction land in Hanjiang,Guangling and Gaoyou is gradually decreasing,the shape regularity is obvious,and the connectivity is increasing.The fragmentation of the urban construction land in Jiangdu is improved,the shape irregularity is obvious,and the connectivity is reduced.The change of the fragmentation,connectivity and the shape irregularity of Yizheng is obvious.The fragmentation of urban construction land in Baoying is fluctuating,and the shape irregularity and connectivity are gradually enhanced.The analysis of the external characteristics of urban construction land expansion shows that the central urban area is the main expansion core area of the scale of urban construction land in the study area.At the same time,there are some sub expansion core areas such as Zhen Zhou of Yizheng,Economic Development Zone of Gaoyou,Baoying Development Zone and so on,and there are differences in the scale of urban construction land expansion in different expansion core areas as time goes on.The expansion intensity of urban construction land in Yangzhou is consistent with the expansion of the core areas in different periods.The characteristics of agglomeration and expansion of urban construction land in Yangzhou are more obvious arounding the central city,Zhou Town of Yizheng Zhen,economic development zone of Gaoyou,and Baoying County Development Zone which are the core area of expansion strength.The analysis of the expansion direction of urban construction land shows that the expansion intensity of urban construction land in the south and southwest regions is obviously higher than that in the northern region.Extending from???the center of the city,urban construction land showed a "leapfrog" expansion,and forming a plurality of secondary wave.(3)The result of the study on the landscape pattern effect of the expansion of urban construction land shows:From 2005 to 2013,the arable land was the main source of urban construction land expansion in Yangzhou,followed by rural settlements and waters,which accountis for 55.73%,27.91%and 8.39%of the total amount of urban construction land expansion in Yangzhou separately.The increase of urban construction land expansion intensity results in the reduction of the fragmentation of landscape level,the increase of landscape connectivity,and the decrease of landscape diversity.The impact of urban construction land expansion on arable land,woodland,waters and rural settlements is more significant,resulting in the improvement of landscape fragmentation and shape regularization of arable land,woodland and waters,as well as the decrease of patch connectivity.The increase of urban construction land expansion results in the reduction of the fragmentation of rural settlements,and the improvement of the connectivity and shape regularization.In the main direction of urban construction land expansion,the development of urban construction land reduces the degree of landscape fragmentation and diversity of landscape,and enhances the connectivity.The most affected landscape types are arable land,waters and rural settlements.But other landscape types are less affected because of less distribution.In the main direction of urban construction land expansion,the expansion of urban construction land causes the fragmentation and connectivity of the arable land and waters landscape to be reduced,and the shape of them tends to rule.With the expansion of urban construction land,the fragmentation of rural settlements is reduced,and shape regularization and connectivity of it are improved.(4)The simulation results of urban construction land expansion show that the expansion of urban construction land takes up divers scale of other landscape in different scenarios,but the number of rural settlements is the largest.In the inertial development scenario,most of the new urban construction land is clustered in the low landscape security region,and occupies a high scale of arable land,waters and woodland.In the basic security scenario,most of the new urban construction land is distributed in the middle landscape security pattern region.Compared to the inertial development scenario,the scale of occupied arable land is increased,and the size of the occupied waters and woodland is reduced.The optimal protection scenario occupys a relatively high proportion of arable land compared with the inertial development scenario and the basic security scenario,but????which concentrates on the high landscape security region mostly.The scale of the occupied waters and woodland is reduced.Landscape pattern index is divers in three scenarios compared with 2013.In the inertial development scenario,the change of landscape patterns is conducive to the development of urbanization,which counts against the mechanized production of arable land and the ecological service function of woodland and waters.In the basic security scenario,the change of landscape pattern is beneficial to the social and economic development of urban and rural areas to a certain extent,and the damage degree of waters and woodland is lower than that of the inertial development scenario.In the optimal protection scenario,the change of landscape pattern is more conducive to the regional social,economic and ecological development.In the inertial development scenario,the ecological infrastructure should be planned properly and the permanent basic farmland should be delimite strictly.In the basic security scenario,the government should give full play to the ecological bottom line function of the landscape security pattern,and guide the rational development and layout of the urban construction land.In optimal protection scenario,the government can improve the level of land intensive by measures of stock construction land exploitation and so on.