| The fifth climate change report released by IPCC reconfirmed that the climate change is happening all over the world, so how to address climate change has become an important environmental issue for governments around the world. Agricultural production is both the "source” and " sink” of the greenhouse gases. On the one hand,farmland soil and crops have carbon sequestration effect, on the other hand, chemical fertilizers, pesticides, agricultural films, soil tilling and fossil fuel consumption would lead to huge amounts of carbon emissions. With the increase of chemical material usage and intensity of farming, the situation for our country to increase carbon sequestration and mitigate greenhouse gas emission is very serious. Therefore,enhancing the agricultural carbon budget and the evaluation of spatio-temporal variations of carbon efficiency, which helps to promote energy conservation,emissions reduction and carbon sequestration in agriculture, has become one of the most urgent problems. This thesis focuses on the example of Poyang lake eco-economic region, using the statistical data from 2000 to 2010 to analyze the carbon input and output, estimate carbon efficiency in Poyang lake eco-economic region, and clarify the carbon budget and spatio-temporal variations of carbon efficiency in Poyang lake eco-economic region. All of these researches are on the reason of providing a scientific basis for Jiangxi province to make policies to mitigate and fit in climate change. The main research conclusions of thesis as follows:(1) The overall amount and intensity of carbon emissions in Poyang lake eco-economic region was in a growth trend. The agricultural carbon emission amount rose by nearly 42.34% from 0.7613 million t to 1.0836 million t from 2000 to 2010.The agricultural carbon emission intensity grew from 356.24 kg·hm-2in 2000 to467.92 kg·hm-2 in 2010, the up rate was nearly 31.35%; On the six kinds of carbon source in Poyang lake eco-economic region, fertilizer is the primary, whose annual average carbon emissions accounts for 43.07%, followed by agricultural machinery(34.44%), pesticide usage(14.07%), agricultural film usage(7.76%), agricultural land tilling(0.64%) and agricultural irrigation(0.02%). There was basically the same of the relative and absolute variation of carbon emissions changes model of counties inPoyang lake eco-economic region, whose overall volatility was on a slow expanding trend. The standard deviation index increased from 2.21 to 3.14, grew by 48.46%. The coefficient of variation increased from 0.70 to 0.73, the net increase rate was 4.3%.The agricultural carbon emission amount of Poyang lake eco-economic region′s spatial distribution of carbon emissions amount was in an evident cluster features and the high carbon emissions place were mainly distributed in the counties and cities around Poyang Lake.(2) The amount and density of agricultural carbon sequestration was in a fluctuated growth trend. The amount of agricultural carbon sequestration rose from1.1792 million t in 2000 to 1.7458 million t in 2010, the net growth rate was 48.04%.The density of carbon sequestration soared from 495.91 kg·hm-2to 685.39 kg·hm-2,with 38.24% increase rate. The proportion of all kinds of crops in Poyang lake eco-economic region carbon sequestration amount: rice(92.98%), oilseed rape(3.89%), sugar cane(2.84%), cotton(0.29%) and tobacco(0.01%). The high value amount and density of agricultural carbon sequestration in Poyang lake eco-economic region mainly concentrated in counties and cities of Nanchang, Shangrao, Yichun area,while the low value areas mainly concentrated on counties and cities in Jiujiang; The amount of agricultural carbon sequestration in Poyang lake eco-economic region was significantly higher than the carbon emissions, which showed that the farmland ecosystem in Poyang lake eco-economic region had great carbon sink function.However in recent years, the growth rate of agricultural carbon emissions was obviously higher than carbon sequestration.(3) From 2000 to 2010, the production efficiency of agricultural carbon in Poyang lake eco-economic region was rose from 9.27 kg·kg-1(CE) to 10.16kg·kg-1(CE), the economic efficiency of agricultural carbon declined from 10.73Yuan·kg-1(CE) to 9.25 Yuan·kg-1(CE), and the ecological efficiency of agricultural carbon increased form 1.76 kg(C)·kg-1(CE) to 1.94 kg(C)·kg-1(CE). The agricultural carbon efficiency in Poyang lake eco-economic region had an obvious characteristics of spatial agglomeration, with most cities and counties in jiujiang areas are low efficient, while the high efficiency area mainly concentrated in the south east cities and counties of Poyang lake eco-economic region. In certain level of agricultural carbon emission, the production efficiency of agricultural carbon is influenced by agricultural development level and agricultural economic output. The economic efficiency is impacted by grain production and price, and the ecological efficiency is mainly affected by agricultural carbon sequestration. Most counties and cities inPoyang lake eco-economic region are carbon sink area where the agricultural carbon sinking function is distinct, moreover, the high carbon sink areas are increasing year by year.(4) There is a long way to go for farmland ecosystem in Poyang lake eco-economic region to increase carbon sequestration and reduce carbon emission.According to the present situation of agricultural development in Poyang lake eco-economic region, the future tasks to increase carbon sequestration are in four aspects: developing low-carbon agriculture, optimizing the structure of agricultural industry, rationally utilizing agricultural chemicals and planning agricultural efficiency areas. |
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