| With rapid economic development,China's total carbon emissions ranks first in the world,and under the greater pressure to reduce carbon emissions in international climate negotiations,it is imperative for China to develop low carbon economy.As a developing country,Chinese government undertook the responsibility of carbon emission reduction actively,and set the goal to reduce carbon emission reduction aim as:carbon emission intensity per GDP in 2020 by 40 to 45 percents compared to that of 2005.Land use change is one of the most important human activities to increase CO2 concentration in the global atmosphere,for it not only affect carbon storage directly in terrestrial ecosystem,but also influence carbon emission activities on land surface indirectly since every human activity makes the land as its carrier.The coastal area is a region with high density of human activities,where the land surface has been greatly disturbed by human activities,land use/cover changes,and with high density of energy consumption and the burning of fossil fuel.Overall,the coastal area and its land use/cover changes play a decisive role on regional carbon emissions.China is on the stage of fast urbanization,and with the implementation of a series of coastal development strategy,the urbanization develops rapidly in the coastal areas,which leads to obvious land use/cover change and the increase of carbon emission.The development plan of Jiangsu coastal area had been authorized by the Sate Council,which will bring great changes in future.Therefore,analyzing carbon emission mechanism of coastal land use,calculating carbon source and sink capacity of different land use types,analyzing land use changes and its carbon emissions characteristics in coastal area,will help to develop low carbon emission land use pattern,which is very important to reduce the pressure of decreasing carbon emission in China.Based on the summarization of research on carbon emission brought by land use changes and land use changes in coastal area both in China and abroad,the dissertation analyze land use changes between 1985-2010 in coastal area of Jiangsu Province,China,calculate carbon source/sink in terrestrial ecosystem,carbon emission from energy consumption,carbon emission from industrial production,carbon emission from garbage,and from people and animals,established the relationship among different carbon emission items and different land use types as farmland,woodland,grassland,water area,shallow,urban land,rural residential land and other construction land,respectively,analyze the effect of carbon emission brought by land use changes,and form the carbon emission list fitting the character of coastal area.This dissertation also use the method of system dynamics to establish simulation model for carbon emissions brought by different lands,which can simplify the complex calculation process and to provide a new method for the calculation of carbon emissions from land use.Furthermore,this dissertation proposes an optimized land use structure in 2020 and found it can reduce carbon emission obviously,make the spatial variation simulation through the CLUE-S model under different scenes,and propose land use management measure based on low carbon.The main conclusions are as follows:(1)The temporal and spatial change of land use in coastal Jiangsu:Due to the effect of shallow sedimentation,the total study area increased from 1985 to 2010.For different land use types,farmland and grassland had decreased continuously,the area of woodland and shallows decreased fluctuantly,and the area of water area,urban land,rural residential land and other construction increased.2005-2010 was the period with the most obvious land use changes.The main land transfer types were:farmland and water area-construction land,coastal grassland-water area,farmland and other construction land,water area-farmland.The percentage of transferred land of Nantong is the largest,followed by Yancheng and Lianyungang.The buffer area with the distance of 0-20 km to coastline presented the most obvious land use transfer,and especially within the 0-10 km buffer area,with a high transfer rate of 27.55%.The buffer area of 20-40 km to coastline presented the lowest land use transfer rate,in the 40-100 km to coastline buffer area,the land use transfer rate was 8.92%-10.92%,overall,the rate decreased with the increase of distance to coastline.(2)Carbon emissions change in coastal Jiangsu:Total carbon emission in coastal area of Jiangsu Province increased 2.8 times,with energy consumption contributed the most,especially in the period of 2005-2010.Carbon absorption in terrestrial ecosystem increased but not obvious,with annual carbon sink capacity between 52.45-72.15 million tons between 1985 and 2010.Which can offset 13.13%carbon emission from energy consumption in 1985,but only 5.2%and 3.2%in 2005 and 2010,respectively.These offset percentages were much lower than the average value of the whole country in the same period,so the coast area of Jiangsu Province suffered great pressure to reduce carbon emission,especially in Nantong.(3)Effect of carbon emissions of different land uses in coastal Jiangsu:average carbon emission intensity per unit land area increased from 244.11 t.km-2.a-1 in 1985 to 895.96 t.km-2.a-1 in 2010,and the increasing rate was very fast after 2000,especially after 2005.The carbon emission density of farmland,woodland,grassland,water area and shallows did not change much,but the change was obvious for construction land,especially for other construction land.The carbon emission density increased three time during 1985-2010,and increased 0.9 and 0.27 times for urban land and rural residential land.The average annual carbon emission during 1985-2010 reached to 1408.48 million tons,including 41.48 million tons brought by land use changes.Although it only accounted for 3%of the 1408.48 million tons,the 3%percentage is 7.5 times of the percentage that the transfer land accounted for the whole study area.It can be seen that land use change is a main driving factor to affect carbon emission.The transfer from farmland to construction land(especially urban land)contributed the most to the increase of carbon emission,which mainly located in the area 0-20 km to the coastline.(4)Land use structure in 2020 and its spatial distribution simulation in coastal Jiangsu:under the natural growing mode,total anthropogenic carbon emissions will reach 7027.51 million tons,which increased 1.2 times compared with that of 2010.The total carbon emission amount(including terrestrial ecosystem)will amount to 6947.16 million tons,which is 1.4 times compared with that of 2010.Under the land use structure optimization in 2020 based on low carbon,total carbon emission will decrease 2080.35 million tons by a rate of 30%compared with the natural growing mode,and it is only 673.54 millions tons more than that under the land use structure of 2010,so the optimized land use structure performed well to reduce carbon emission.The spatial simulation made by the model of CLUE-S showed:area near the coastline will have high probability of land transfer,so we should strengthen land management in this area.The main land transfer type will be farmland and shallow to construction land(especially urban land),rural residential has great consolidation potentiality,it will be the main factor to reduce carbon emission in future.(5)Low carbon land use regulations in coastal Jiangsu:Developing low carbon economy is indispensable for the coastal area.The main measures are suggested as follows:The protection for ecological vegetation,the management of soil and the protection of water area and coastal wetlands should be strengthened,the area of green land should be expanded,the coastal industrial park land use should be allocated rationally and its management be strengthened,the expansion of construction land should be controlled strictly,industrial structure should be adjusted and optimized,the coastal tourism should be developed vigorously,and the development of new energy should be sped up with low carbon emission. |
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