Study On Land Use Cstange And Its Effect On Carbon Emission In Ganjiang Upstream Watershed

The main cause of climate change is that such glasshouse gases as CO2,CH4 and so on in the atmosphere have become denser than ever because of human activities such as the consumption of fossil fuels and land use change.Taking Ganjiang upstream watershed as the study area,based on five Landsat TM images of 1990,1995,2000,2005 and 2010,we analyzed the temporal change of land use structure,the degree of land use change and the information entropy of land use structure.Based the grey correlation analysis and Boosted Regression Trees,we analyzed the driving factors of farmland,forest land and construction land.Various land use change carbon emission were calculated by the usage of the carbon emissions coefficient of various land use type.We analyzed the carbon emission mechanism of land use and the relationship between the land use change and carbon emissions,then explored the relationship of carbon emissions and economic growth in the studied area in detail.By using the residual LMDI decomposition method and the expanded decomposition model based on Kaya identical equation,we carried on the comprehensive quantitative analysis for the driving factors of carbon emissions in the studied area.Finally,based on the above study,we drew a lesson from domestic and foreign advanced experience and combine with the actucal situation of Ganjiang upstream watershed,draw a theoretical guidance on carbon reduction technology path in Ganjiang upstream watershed.The main research conclusions are as follows:Firstly,the land use change and its driving force analysis results showed that the forest land is the main land use type in Ganjiang upstream watershed.The forest land area increased most from 1990 to 2010.Among them,the coniferous forest area increased by1.06×10~5hm~2,the Broad-leaved forest area increased by 3.22×10~4 hm~2,the mixed needle leaf area increased by 7.79×10~3 hm~2,the bamboo forest area increased by 9.93×10~3 hm~2,the other forest area increased by 3.99×10~3 hm~2.The grass land area decreased most from1990 to 2010.The amount of forest land and construction land increased in 20 years,the amount of cultivated land,grassland,water area and unused land reduced in Ganjiang upstream watershed.The biggest change range is construction land,the second is grassland,and the lowest is forest land.The dominant land type of land use structure change is the woodland and grassland from 1990 to 2010.And there was the trend of increase or decrease fluctuations in the influence of human activities on the land use degree.The socioeconomic driving factors which were the most affected the farmland change,was the change of the average annual income change of farmers,which influenced about 25.6%of the farmland area change and reflected the negative relation from 1990 to 2010.The socioeconomic driving factors which were the most affected the forest land change,was the change of theforestry output value of agriculture animal husbandry fishery output ratio,which influenced about 83.7%of the woodland area change and reflected the positive relation.The socioeconomic driving factors which were the most affected the construction land change,was the change of GDP,which influenced about 89.9%of the construction land area change and reflected the positive relation.Secondly,it was found that the construction land was the main carbon source through the evaluation of land use carbon emissions in Ganjiang upstream watershed,and the second was farmland.Forestland was the maximal carbon sinks type,next was grassland,water and unused land.The net carbon emissions showed the carbon sinks.The carbon emissions increased year by year,and it increased 24.15 Tg C in the past 20 years.Thirdly,the analysis of carbon emission effect showed that there was a big difference in the correlation between the land use change and the total carbon emission.Among different stages,change law was not the same.It was a weak effector phase of the land use structure change between 1990 and 1995.There was a weak effect of dynamic change of land use structure on the total carbon emission.It was a negative effector phase of the land use structure change between 1995 and 2000.Due to the shrinking of construction land area,the carbon emissions of land use change reduced.It was a positive effector phase of the land use structure change between 2000 and 2005.Land use structure change played a leading role in carbon emission change to some extent.The degree of effect was general.It was a surged effector phase of the land use structure change between 2005 and 2010.Land use structure change played a decisive role in carbon emission change to a great extent.The degree of effect was great.Fourthly,the analysis of driving factors of carbon emissions based LMDI showed that the increase of CO2 emission is strongest and steady due to economic scale and energy intensity.Industrial structure and way of life also showed strong driving action.The historial driven contribution of energy structure,the life level,population scale and the structure of urban and rural,with a vital driving force,which should be seriously considered.Finally,we put forward several policy proposals according to this article research conclusion.(1)We would carry out vigorously afforestation,and adjust land use structure to reduce carbon emissions and increase carbon absorption.(2)We would control the scale of construction land strictly,adjust land use intensity and efficiency,and control the carbon emissions of construction land.(3)We would develop new energy vigorously,adjust energy consumption structure,and improve energy utilization efficiency.(4)We would push forward the regulation and protection of land resources,reinforce and carry out the land use policy,and promote low carbon utilization of land.(5)We would enlarge the construction of ecological environment,and promote low carbon land use.