| Global climate change has attracted worldwide attention. Human activities, industrial emissions and the use of fossil fuels lead to the increase of carbon dioxide emissions and the global greenhouse effects have been added. The ecological system of agriculture has played an important role in global greenhouse gas circulation. Agriculture is not only carbon cool but also carbon source. On the one hand crops may fix carbon, on the other hand soil respiration, the use of chemical fertilizers, raising livestock and agricultural wastes can cause carbon emissions. The climate change caused by greenhouse effects will influence the agricultural industry and the agriculture is influenced by climate change easily. Facing the serious challenge of climate change, our government has decided that carbon dioxide emissions will be declined 40% ~ 45% in 2020 contrast to 2005. The FAO puts forward that low carbon agriculture can curb climate change, increase agricultural production in developing countries and maintain the sustainable development of agriculture and fixing carbon ability, which have the dual positive meaning for our country's food security and mitigating climate change trend. Heilongjiang province is a big province in food grown and animal husbandry and carbon fixation and emissions occupies a high proportion. Because straw return to the field ratio is low,carbon emissions from livestock production and residents living energy-using are big and agricultural waste do not recycle effectively, at present most countries in Heilongjiang province adopt conventional agriculture mode named high investment, high consumption , high emissions and low efficiency mode. Heilongjiang province is exploring a development way of ecological agriculture, circulating agricultural and organic agriculture. Different regions has formed different development modes in Heilongjiang province, which promote the development of circulating agriculture and low carbon agriculture of Heilongjiang.This paper,bonded by village and taking year as unit, has estimated and ayalysed the carbon pool, carbon source and carbon absorption, fixation,emissions and transfer of four village regions in agricultural ecosystem in Heilongjiang province through using survey, experimental analysis and model calculation methods. Also we researched the stabilities of agricultural ecosystem of four village ecosystem by using logistics compartment model. We have made forecast on carbon emission trend on the four villages'agriculture ecosystem by way of recursive model.We estimated carbon emissions of farm ecosystem and raising livestock during agricultural industry of Heilongjiang province. At last we presented the strategy of improving carbon fixation, decreasing carbon emissions and developing low carbon agriculture in Heilongjiang province.The paper drawed an inference following conclusions from analysis above:1. Our paper selected four typical villages as our studies. They are Xinzhuang village which developed organic agriculture by using methane, Xingsheng village that founded a indent mode in seed industry named company,base plus farmer, Fenglin village that was a urbanization village and developed a recycling agriculture mode and Tongle village that developed conventional agriculture.2. Crops carbon uptake contents of Xinzhuang village,Xingsheng village, Tonghe village and Fenglin village were 8414t,5699t,9138t and 7301t,respectively.The crops carbon abporption value in growth period is proportional to village crop's output. Carbon uptake intensity were 7.2t/hm~2,4.2 t/hm~2,6.8 t/hm~2 and 9.1 t/hm~2,respectively. Carbon uptakeintensity of crops were proportional to crop output per unit area.The more output comes from unit area, the more carbon absorption from crop in growth period. The average carbon absorption intensity for the four villages is 6.8t/hm~2. . The carbon absoption intensity of each crop ecosystem in proper order is: potato>beets>corn>sunflower>soybean>kidney been in point view of carbon absorption capability of farmland ecosystem.3.Carbon uptake contents in agricultural ecosystem of Xinzhuang village,Xingsheng village, Tonghe village and Fenglin village were 11323t,13725t,16762t and 14156t,respectively. Carbon uptake intensity were 9.1thm~2,8.5thm~2,10.6thm~2 and 14.1 thm~2,respectively. Carbon uptake contents in agricultural ecosystem of four village regions were different significantly. The reason was that four village regions have different soil type, land areas, crops yields and planting types.From the point of carbon absorption capability, Carbon uptake capacities of woodland were much higher than those of farmland.4.Carbon emissions in agricultural ecosystem of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 29201t, 30414t, 36532t and 18541t, respectively. Carbon emissions value in agricultural ecosystem of four village regions were different significantly.(1) Carbon emissions contents of crops planting of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 1243t,578t,522t and 335t.Rice areas of Xinzhuang village were very big and carbon emissions contents caused by crops planting were much higher than those of other three villages. There are four carbon emissions ways during crops planting such as agricultural electricity, field irrigation, chemical fertilizers and agricultural machinery use. Carbon emissions contents caused by chemical fertilizers were the most and the ratios of carbon emissions contents caused by chemical fertilizers and carbon emissions contents of crops planting were 35%,91%,85% and 87%, respectively.(2)Carbon missions of raising livestock of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 41t,64t,12t and 39t. Carbon emissions of raising livestock were connected with numbers and types of raising livestock.(3)Carbon emissions of soil respiration of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 19465t,24240t,24034t and 14782t. Carbon emissions contents of soil respiration were connected with soil areas and soil types.Village land mainly is farmland and so carbon emissions of soil respiration of farmland were the most. The ratios of carbon emissions of farm accounting for carbon emissions of soil respiration were 96 % ,91 % ,90 % and 87%,respectively. (4) Carbon emissions of persons of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 1007t,611t,1245t and 438t, respectively.Evident differences of carbon emissions of persons of four villages were connected with numbers of persons.(5) Carbon emissions of live energy were 7572t,4921t,10630t and 2927t.The average carbon emission intentity of live energy per year are 2.3t,2.6 t,2.8 t,2.2t respectively. This was connected with live energy consumption structure of farmers. Straw was the main live energy of Tonghe village and Xingsheng village with low efficiency of energy usage and high carbon emissions of live energy.Xinzhuang Village use straw and biagas as live energy.Fengling Village use straw fixation fuel as energy of warming and use biogas as energy for cooking,which has obvious effect on energy conservation and emission reduction.5. Carbon fixations of agricultural ecosystem of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village in 2010 were 669t, 532t, 302t and 800t, respectively. Carbon fixations of Xinzhuang village which developed organic agriculture and Fenglin village which developed cycling agriculture were very high.6.Carbon contents transferred out of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 3897t,2746t,5212t,5192t,, respectively in the year of 2010,The carbon value transferred out of village ecosystem in proper order is Tongle> Fengling> Xinzhuang> Xingsheng.The percentage of Crop transferred carbon value accounting for carbon value transferred out of village ecosystem is 98%,92%,99%,77% respectively.The carbon value transferred out of vallige ecosystem is mainly from agriculture product and livestock prodocut take few percentage.7. By way of estimating analysis on carbon absorption value and carbon emission value of farm ecosystem in four typical villages, we get the result that carbon emission is much lower than carbon absorption.Carbon uptake contents were 11 times higher than carbon emissions contents. All these showed that farm ecosystem of village regions in Heilongjiang Province had high carbon pool abilities. Carbon pool contents of farm ecosystem of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 7171t,5121t,8527t and 6946t,respectively and carbon pool intensity were 6.17t/ hm~2,3.74t/ hm~2,6.3t/ hm~2 and 8.7t/ hm~2,respectively.The average carbon pool intensity is 6.2t/hm~28. By way of estimating analysis on carbon absorption value and carbon emission,carbon fixation and carbon transfer,carbon emissions contents of agricultural ecosystem of four village regions were much higher than carbon uptake contents and carbon emissions contents were 2 times higher than carbon uptake contents. All these showed that agricultural ecosystem of village regions were carbon emission source. Carbon emissions source of Xinzhuang village, Xingsheng village, Tonghe village and Fenglin village were 17485,16690t,19970t,4385t,respectively and carbon emissions source intensity were 14t/hm~2,10.4t/hm~2,12.6t/hm~2,4.4t/hm~2,respectively.The arerage carbon emission intensity of the four village is 10.4t/hm~29.Logistic compartment method show that Xingzhuang village in organic ariculture mode, Fengling village with developing cycle agriculture mode and Xingsheng village with developing high efficient and specific agriculture is tend to reach a stable agriculture ecosystem as long as they maintain current agriculture structure and current status of carbon emission and carbon absorption.Tongle Village with developing tradition agriculture production mode is tend to unstable agriculture ecosystem based on current agriculture production structure.10.Estimations of carbon balance of agricultural ecosystem in view of different agricultural development projects showed that carbon emissions of farm ecosystem were the lowest,carbon absorption contents were the highest and high carbon agriculture of high energy consumption,high material consumption, high emission and high pollution might be transformed to low carbon agriculture of low energy consumption,low material consumption, low emission and low pollution if the project that adopted 10% traditional agriculture,50% cycling agriculture plus 40% efficient agriculture was carried out.11.The recursive mode has demonstrates that crop carbon absorption value is in obvious increase in Heilongjiang Province.Carbon absorption has increased from 21240000t of the year of 2000 into 46850000t in the year of 2009 with 121% increase.Farmland ecosystem carbon emission basiclly is in increase gradually trend and carbon emission has increase from 3010000t in the year of 2000 into 5326000t in the year of 2009.Farmland ecosystem carbon pool demonstrates obvious intensitive trend.The yearly change trend of carbon pool and carbon absorption are similar.12. Carbon emission total value of livestock in Heinglongjiang province from 2000 to 2009 has increase from 397100t for the year of 2000 into 608800t for the year of 2009, with 56% increase. Carbon emission from ruminant animals accourts for 70% of raising livestock for the carbon emission of livestock in Heilongjiang Province in 2009.13.Carbon emissions of rural population of Heinglongjiang province were declining gradually. Carbon emissions declined from 6010000t of 2000 to 5590000t of 2009. Carbon emissions declined 6.9% in 2009 contrast to 2000.14. Carbon emissions of live energy of village of Heinglongjiang province in 2009 were 5797t.15. Carbon emissions from soil respiration of plowland of Heinglongjiang province increased evidently. Carbon absorption rised from 153870000t of 2000 to 207970000t of 2009. Carbon absorption increased 34% in 2009 contrast to 2000.16. It was estimated that carbon absorptions of agricultural ecosystem of Heilongjiang province in 2009 were 46850000t and carbon emissions were 280890000t. Carbon pool contents were 234040000t.17.Based on analysis on current status of agriculture ecosystem carbon cycle in villiges in Heilongliang province, developing mode of village low carbon emission agriculture and rserve force of village low carbon emission, this paper has proposed coutermeasures of developing low carbon emission agriculture in Heilongjiang villges.The measures mainly includes establish and develop local regulations for low carbon emission agriculture, establish technoloty guarantee system for developing village low carbon emission agriculture in Heilongjiang Province, adopt low carbon fertilization technology low carbon emission plant technology and low carbon emission livestock raising technology, strengthen exploring and usage of agriculture renewable resourses,establish low carbon emission village and explore positively on developing agriculture.
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