| Global climate anomaly caused by greenhouse effect has been a global environmental problem that the international community is being payed increasing attention, and the relationship between greenhouse gas emission and human activities is the hot issue that the academic circle both at home and abroad are researching on. Since the emission of carbon-containing compound gas is the main source of greenhouse gas, and the carbon emission brought about by human activities has greatly changed the regional carbon cycling, it has been widely acknowledged to establish a low-carbon development scenario. Served as the spatial carrier of human activities, the land is closely related to the urban expansion, industrial distribution and energy consumption. The change of land use can directly alter the natural regional carbon cycle process and indirectly effect the regional level of human carbon emission. Under the background of a low-carbon development mode, a low-carbon land use regulatory mechanism should be built to adjust the types, structure, scale and intensity of land use. It will have important implications for resolving the conflicts between economic growth and carbon emission reduction.The existing research about the relationship between land use and carbon emissions mostly focused on the assessment of regional land low-carbon use,the effect factors of land use carbon emissions,accounting of regional land use carbon emissions and the carbon effect of land use change.All above research did not contribute to the regulatory pathways and mechanisms for land low-carbon use.First of all,we combed the carbon circulation process and mechanism in urban system comprehensively and clarified the carbon circulation process of different land use types in urban system and the influence mechanism of land use type conversion to carbon circulation which were based on correlated studies both at home and abroad.Secondly, the study constructs the urban vertical carbon flux accounting system,taking Wuhan city as the empirical analysis object, measured and analyzed the vertical carbon flux in Wuhan from 2002 to 2002. Then we set up the relationship between carbon flux and various land use types, measures carbon flux of land use in Wuhan from 2002 to 2012 and analyzed the carbon source/sink strength of land use and land use carbon footprint.Follow that, analyzing the carbon effect of construction land expansion in Wuhan by using the method of EKC and the measurement results of land use carbon flux.Studying on the long-term equilibrium relation between the factors in different land use types and carbon emissions by using the method of multivariate cointegration test. Using the method of LMDI to decompose and quantize the carbon effect of land use change.Finally, we put forward the land low-carbon use regulation mechanism from the aspect of macroscopic planning and microscopic land policy by the comparison between the carbon effect of the different paths of land low-carbon use regulation scheme and the current land use planning.Main study can be listed as follows.(1) We compared the carbon flow process of natural ecosystem with binary urban "Nature- Society" system,then describe the carbon flow features of them, and analyze time and spacial mechanism of urban carbon flow system. We also gave a separate analysis carbon cycle characteristics of agricultural land including cultivated land, garden land and forest land, water body and artificial use land which consists of the traffic land, the residential and industrial land. Discussing the influence mechanismof land use change on carbon process from the two aspects process of natural carbon and man-made carbon, clearing the regulation mechanism of land use change on the urban carbon system,and putting forward the macro-control efforts and micro-control of land policy.(2) Building the urban vertical carbon accounting system, the carbon input accounting system including plant photosynthesis and water carbon-absorption, and the carbon output system accounting including fossil fuel combustion, carbon output in production process, respiration carbon output, the output water carbon-volatilization and waste management,on the basis of all above we determined the calculation methods of all kinds of carbon flux.Then,we calculated vertical carbon flux in Wuhan, and analyzed its carbon running state, the results show that:1). The carbon emissions exerts a trend of increase after decreases first on the whole at the study period, the carbon emissions increasing year by year from 17.1065 million tons to 17.1065 million tons from 2002 to 2010,but reducing from 36.3385 million tons to 32.8814 million tons from the year 2010 to 2012. 2) The carbon effect index rose from 80.67% to 80.67% and the carbon pressure index rose to 11.21 from 7.00 during the study period in Wuhan, the influence of human activities on the processes of carbon increased year by year. 3) The decoupling elastic index between carbon emissions and economic growth is 0.34,stating the weak decoupling in the whole research period,but the decoupling state shows expansionary coupling-weak decoupling- the change trend of strong decoupling trend over the years in the study period.(3) We analyzed characteristics of farmland, artificial land use and waters carbon source/sink, sets up the relationship between carbon flux and various land use types,and measures carbon flux of land use and land use carbon footprint.The results show that: 1) Urban village and industrial land is the main source of carbon output, for example in 2012 output was 87.2 % in 2012. And traffic land is the fastest growing type of land use carbon output, research period increased by 159%. 2) The intensity of non artificial land carbon sink determines the trend of the carbon sink intensity,the intensity of artificial land carbon source determines the trend of the carbon source intensity.3) Urban village and industrial land is the largest carbon footprint land, for example output was 88.32% in 2012. Followed by the traffic land, accounting for 10.74% of the total carbon footprint.(4) Deriving from the theory of carbon effect of land use of city system,and using the Kuznets curve to analyze the relationship between construction land expansion and carbon emission intensity of Wuhan city, the results show that there are some relationships of inverted U curve between the amount of construction land,cities, towns, villages and industrial land and their carbon emission intensity, however, there are a relationship of curve that is type N on the slope between transportation land and its carbon emissions intensity.Decomposing the land use change into five factors including the carbon intensity of land, the land use structure, land use efficiency, economic development and population scale.Using the method of multivariate cointegration to analyze the relationship between carbon emissions and the five factors, and using the LMDI method to quantitative and decomposition the effects of carbon in five factors. The results show that: 1)There is a stable long-term equilibrium relationship between carbon emissions and five factors.2)Economic development performs the strongest stimulus to the carbon emissions and the contribution values achieved 26.2721 million tons. Followed is the land structure effect, the contribution values reached 10.2097 million tons; The contribution values of land use intensity and population scale is relatively small, 5.5087 million tons and 5.1703 million tons respectively. The efficiency of land use on carbon emissions exhibited a repression effect, the contribution values were- 31.3859 million tons.The efficiency of land use has played a positive role in improving urban carbon emission reduction, and the effect is greater than the ill effects on carbon emission reduction of unit land carbon intensity increased and land use structure change.(5) By comparing with the carbon effects of the existing planning scheme,this part analysis the way to control urban construction land with multivariate cointegration, analysis the way to optimize land use structure in low-carbon approaches with multivariate linear programming, and analysis the way to control carbon intensity in land use with Monte Carlo simulation. Starting from the low-carbon regulation approach of land use, this part,firstly, offered space control method guided by land use structure control and optimization, including low-carbon overall land use planning, low-carbon overall urban planning and low-carbon main functional area planning of land use.Secondly, offered the way to make urban land use policy guided by reducing the carbon intensity of land use,which regulate the land supply policies and reduce carbon emissions intensity, realize low-carbon land use.Finally, establish a low-carbon urban land use regulatory mechanism from the space control land on the macro and micro policy instruments.
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