| Global climate change caused by extreme weather,glaciers,species extinction,rising sea levels and various natural disasters,has food security,energy security and ecological environment security is facing serious direct threat in the development of society.A large number of studies show that the impact of global climate change caused by human activities mainly has two aspects: one is the carbon emission phenomenon caused by the consumption of coal,oil and natural gas and other fossil fuels the traditional energy;two is due to greenhouse gas types of land use change caused by excessive discharge phenomenon.According to the WWF report,nearly 10 tons of carbon emissions is neglected because of the change of land use;land use change has significant influence on the content of CO2 increased in the global atmosphere.Therefore,in the context of low-carbon economy,how to achieve low-carbon emissions of land use planning and management is particularly important.This paper takes Chongqing city of five functional areas as the research object,combined with RS and GIS,Markov and Logistic model and CA-Markov model,in1995,2005 and 2015 three periods of land use data on the basis of the analysis of1995-2015 between land use change and its influence factors among Chongqing five functional areas;the establishment of CA-Markov model in Chongqing the five functional areas of future land use change type simulation;Then the carbon emission model was used to calculate the carbon emissions and total carbon emissions of1995-2015 years and future land use types in Chongqing.In order to provide reference for the sustainable development of the typical economic and ecological environmental protection areas in the Three Gorges Reservoir area of Southwest China,and guide the scientific and effective land planning and management work.The main contents are as follows:(1)The land use dynamics of in Chongqing city from the following two aspects: the number of land use and the spatial distribution of land use change in 1995-2015.The major functional areas are the continuous decrease of cultivated land and unused land,and the increasing trend of forest land,grassland,water area and construction land.In the number of 20 years,each district of cultivated land were declining,the urban core function areas and expand the area of cultivated land decreased most,reduce the area ratio as high as 16.20%;forest land continued to increase,the development of the new city area the largest increase,increase the proportion of up to 11.58%;grassland,water and construction land in various functional areas have sustained growth,and the gains are similar;unused land base is small,although it continued to decline,but the overall effect is not big.The change of land use types in the ecological conservation development area of Chongqing and the ecological protection area in Southeast Chongqing remained stable and consistent with the overall change.In spatial distribution,the whole area is mainly farmland,woodland,grassland and construction land in the four most widely distributed;the overall distribution of each functional area of the land use spatial degree of change is the construction land>unused land>cultivated land > grassland >woodland waters.(2)Influencing factors of land use change.In this paper,the factors that influence the change of land use types are mainly three aspects: natural environment,spatial distance and social economy.Have a significant impact on the variation of cultivated land is the social and economic factors,spatial distance factor has an important role on the sustained and stable changes to arable land types;social and economic factors on forest types changed the role of sustained significant;social and economic factors(net income of farmers,the resident population density)and spatial distance(distance to the original grass)on the grass the type of change to play a greater role;impact on water is the biggest change in distance to the original waters of the distance;the social and economic factors on construction land have significant influence,and the importance of the obvious rise;the population density and fuelwood demand and spatial distance factor social economic factors in the distance to the road and the distance to the residents,to a greater impact on the occurrence of unused land up.(3)Land use forecast and precision test.Using Markov model to obtain the transfer matrix of land use area,combined with the effects of land use change factor,make appropriate transformation rules,and then use Logistic regression model to generate land suitability atlas,and then simulate the pattern of land use in Chongqing city in2015 by using the CA-Markov model,and in 2015 the actual land use data comparison,analysis and verify the accuracy of the prediction model the Kappa coefficient reached 0.87,more than 0.75,in line with the simulation accuracy requirements.Therefore,it can be used to forecast the land use change in the next 10 years,that is,in 2025,and to get the data of land use simulation in different situations.(4)Scenario simulation of future land use in Chongqing.In three different scenarios,the types of land use changes in the number,each with a total type gradually stable trend,the speed and magnitude of change also have different degrees of decline;on the space pattern,the most dramatic is the development of land for construction,basically concentrated in the original the construction land and the edge of road edge,so the edge of the original construction land and traffic road to the edge of the farmland,woodland and grassland or water and other land types will have varying degrees of occupation,this is the inevitable result of the development of the city.(5)Analysis of carbon emission effect of land use in Chongqing.During the 20 years from 1995 to 2015,the total carbon emissions in Chongqing were in a state of continuous growth,an increase of 3826.65 ?104t,an increase of 78.80%.The crop is cultivated land in the role of carbon emissions and will produce a certain amount of carbon absorption;as with all major forest carbon sequestration type,the carbon absorption capacity is the strongest in all land use types;grassland,water and unused land manifests itself as a carbon sink;the construction land is the main the carbon source,the carbon emissions intensity is far greater than other land types can absorb the strength,resulting in the entire city of Chongqing showed the state of carbon emissions.(6)Prediction of carbon emissions for future land use types.In scenario 1 the carbon emissions of six types of land,cultivated land,water and construction land are still the carbon source,for the construction of carbon emissions to over 10 years ago,the rapid growth,and the growth rate of 35.80%;woodland,grassland and unused land for these three types of carbon sequestration.Scene 2 overall land use type carbon carbon source unchanged,different construction with the growth of carbon emissions reached a hitherto unknown peak,and other land types from carbon or carbon absorption,are far beyond the reach of the construction land of Chongqing City carbon emissions directly lead to the overall effect of carbon emissions Chongqing city in 2025 showed a surge in state.Increases and decreases under thesituation under the 3 carbon sources and sinks in the relevant measures,but obviously we can see the construction of almost absolute role in the regional carbon emissions carbon source for the effect is weakened;farmland carbon and water emissions have continued to small,but the overall effect is limited;and the forest and grassland and unused land three plays a major role as a carbon sink for the type,the promulgation and implementation of related policies,enhancement of carbon absorption intensity obviously.Due to the overwhelming effect of the construction land carbon emissions intensity greatly weakened,so that the situation in the case of 3 of the total carbon emissions growth rate is the smallest,only about 18.65%. |
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