Study On Carbon Emission Effect In Chengdu Plain Area Based On LUCC

Land use/cover change caused by human activities is the main source of the increase of atmospheric carbon content,and plays an important role in carbon exchange between land and atmosphere.Land is not only a natural carrier of carbon emissions from terrestrial ecosystems,but also a space carrier of carbon emissions from socioeconomic system.Changes in human production and lifestyle resulted by land use was also brought incalculable indirect carbon emissions.Based on the land use/cover change(such as deforestation,reclaim land from lakes,urban expansion etc.),this paper research carbon emissions caused by ecosystem types replacement,which will has important theoretical and practical significance for understanding the law and mechanism of carbon emission and its cycle in Chengdu plain area,formulating effective measures for energy saving and reducing carbon emission,and making the corresponding policy for each region.This paper,relying on the "Key Laboratory of the Ministry of education" and the National Natural Science Fund project,and the Chengdu plain area is selected as the research area.With Landsat TM/ETM+ and Landsat 8 OLI images in 2000,2007,2008,2015 as the data source,the spatial-temporal revolutionary characteristics of land use/cover change in Chengdu plain area was analyzed in this paper,based on RS and GIS technologies,following the software of the ArcGIS 10.3,ENVI 5.3,In VEST 3.3.1,Origin 8,geographical detectors and other related software.Based on land use types and carbon density of Chengdu plain area,the temporal and spatial distribution of both carbon reserves and carbon sequestration of the research region for the fourth phase were carried out through the InVest model,and had been used to analyze the characteristics of spatio-temporal variations of carbon reserves and carbon sequestration in study area and the emission effects in the view of land use changes.There were 15 factors about natural ones such as the type of vegetation,climate and topography and human-caused ones such as urbanization and industrial structure had been used to analyzed the driving factors for carbon reserves and carbon sequestration in the study area through geographical detector method.The results showed that:(1)The spatio-temporal change of land use was remarkable.The farmland and woodland were the principal type of Chengdu's land use type,especially the farmland which made up 44% of whole region.Followed by construction land,forest accounted for some 32% of the entire region,water,grassland and untapped land accounted for about 4% of the total.During the past 15 years,while cultivated land showed a downward trend,it constituted the largest proportion of the total land,increasing and decreasing area is mainly concentrated in the plain area,but the mountainous area is less.The forest increased at first and then decreased,which was completely the opposite of the tendency of grassland.The area of unused land showed a fierce fluctuation,compared with the constant one of water,while the construction land showed an increasing trend year by year,the main manifestation is the urban expansion in Chengdu central region.(2)The spatio-temporal changes of carbon reserves amount were apparent.The carbon reserves of 2000,2007,2008 and 2015 in Chengdu plain were 121.781 Tg,117.798 Tg,120.635 Tg,116.345 Tg,respectively.The change trend of carbon reserves in different land types was consistent with the transformation of land use types.The carbon reserves of cultivated land in the study area decreased gradually from 70.044 Tg in 2000 to 51.595 Tg in 2015,reduced 18.449 Tg.Forest carbon reserves amount increased year by year at a rate which showed a decrease tendency.Forest carbon reserves amount in 2000,2007,2008 and 2015 were 48.314 Tg,58.171 Tg,63.277 Tg,60.332 Tg respectively.The carbon reserves in the construction land experienced a dramatically decline after a sharply increase.The carbon reserves amount of grassland declined slightly from 1.368 Tg to 1.214 Tg.The unused ground carbon reserves showed a fluctuating trend.The change of carbon reserves in different districts and counties are small during the four period of research time.(3)There is a significant carbon emission effect in the Chengdu Plain area caused by the change of land use types during the study period.The total carbon sequestration of 2000~2015 is minus 5.436 Tg,which indicated that the Chengdu plain was a carbon source area during the past 15 years.The amount of carbon sequestration in Chengdu plain,during2000 to 2007,is minus 3.984 Tg,which meant that during the study period,Chengdu plain area served as a carbon source.From 2007 to 2008 the carbon sequestration capacity was 2.838 Tg,which indicated that the Chengdu plain area turned into a carbon sink.However,from 2008 to 2015 the carbon sequestration capacity of was minus 4.290 Tg,Chengdu plain transformed into a carbon source area again.(4)Natural and human disturbance factors had significant influence on carbon reserves.The natural factors such as vegetation type,elevation and soil type and population factors,like GDP per capita and industrial structure,interacted fiercely with each other,had great influence on carbon reserves in the study area.With the expansion of construction land and the development of urbanization,the impact by human disturbance factors on carbon sequestration was gradually enhanced.The greater the intensity of human action on the earth's surface,the higher the carbon emission.(5)Refining the planning of land use types in the study area,making a master plan for agriculture,forestry,animal husbandry,industry,city and residential construction,ensuring the amount area of each land use type,and exerting a rigid control over all kinds of land use would provide a considerable reference for the ecological value of land the use.