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1、区域可持续发展与人地关系行为机制模型研究石 敏俊筑波大学区域可持续发展与人地关系行为机制模型研究 区域可持续发展与农业环境政策人地关系行为机制模型框架的建立：外部社会经济因素影响人地关系变化的机制鄂尔多斯高原：人地关系行为机制模型与退耕还林对水土保持影响的比较静态模拟自然科学与社会科学相融合的必要性区域可持续发展与农业环境政策 欧美国家的农业环境政策石油农业的化肥农药高投入导致水质污染等环境问题价格支持政策导致农产品过剩农业环境政策的核心是推行农业粗放化经营，减少化肥农药投入，减少农产品产量对于实行粗放经营的农户给予政策补贴发展中国家的农业环境问题土地退化引起的农业环境问题沙漠化，水土流失，盐
2、碱化环境负荷引起的农业环境问题水质污染，土壤污染土地退化的人为因素人口压力，农业技术水平依赖资源投入的静态增长导致农业粗放再生产和土地利用的平面扩张，土地利用超过环境容量时带来土地退化发展中国家的农业可持续发展解决土地退化问题的出路在于发展可持续集约农业可持续集约农业：通过集约化达到可持续集约化：对少量土地实行集约经营，技术密集投入，提高单位土地面积生产力水平，为大面积退化土地休生养息恢复生态、实现区域可持续发展提供条件保护环境与发展经济的关系发展中国家的农业环境政策解决土地退化问题的农业环境政策应当结合发展可持续集约农业来展开发展可持续集约农业的关键是技术进步，开发实用适用技术实用：实际农业
3、活动中可应用的技术适用：适合当地条件适合当地农户采用的技术发展集约化（技术进步和技术推广）的政策补贴可作为环境保护投资进入环境经济核算人地关系行为机制模型框架：社会经济因素影响人地关系变化的机制影响人地关系和环境生态变化的社会经济因素人口增长市场和价格变动技术进步制度和政策收入和消费期望单一或综合的因果关系分析不能阐明社会经济因素影响人地关系变化的机制ResourceEnvironmentLand UseAgriculturalActivityInstitutionPolicyTechnologyMarketPriceResource ConstraintImpact onEnvironmen
4、tPopulationgrowth外部社会经济环境与人地关系变化Literature reviewFarm household decisions on land use activities and technological choice affect the soil quality and therefore play an important role in aggravating or reducing land degradation process.Farm household decisions are dependent on relative prices of outp
5、ut,input and production factors,and other socio-economic circumstances that are influenced by macroeconomic and agricultural policy.Agricultural policies affect soil degradation by influencing the level of output,input and factor prices(Heerink,2001).社会经济因素影响环境变化的机制政策和制度外部社会经济环境农户经济行为资源环境变化反馈：资源环境变化
6、农户经济行为（资源环境退化对经济福利的影响，现在价值与将来价值的关系）外部社会经济环境变化：价格变动，技术进步，资金和信用约束政策和制度：经济政策和环境政策，资源分配和资源利用秩序Conceptual frameworkPolicy reformSocio-economic environmentHousehold decisionLand degradationMacro and Regional ModelsHousehold and Village ModelsBio-economic ModelsBio-economic household ModelBio-economic vill
7、age Model approachEconometric estimation approach:Lack of consistent data,especially long time series data about effect of soil degradation;Difficult to derive function form of the reduced-form equation.Meta modeling(Decision rule)approach:Estimate a statistical relationship between exogenous and re
8、levant endogenous variables;refer to a black-box representation of relationship between exogenous and endogenous variables;Bio-economic village Model-continueMathematical programming approach:A major advantage of LP Model is that can combine economic behavior and biophysical process in an integrated
9、 framework.Leontief input-output coefficients permits the combination of incompatible economic and biophysical production function.A disadvantage of LP Model is that may generate vast amount of what-if results if some of parameters of the model are not known with great accuracy.鄂尔多斯高原人地关系行为机制模型Bio-e
10、conomic village LP ModelShort-term analysis:one year due to uncertaintyVillage model:appreciate level of analysisObjective function：maximizing benefit of householdsProduction function：Leontief input-output coefficients Consumption function：consumption choice based upon nutrition and prices under con
11、straints of basic nutrition intake demand and hobbySoil conservation process：converted land supplyFeedback of soil erosion to production：no feedback processBio-economic village LP Model(1)s.t.(2)(3)(4)(5)(6)Variable definition:household discounted utility:period:crop:land type:land endowment:the are
12、a of crop produced on land type in period:the per unit price of crop or livestock output:the yield function for production of crop c or livestock v:a vector of inputs used in production of crop c or livestock v:the per unit input price for input Variable definition-continue:the crop or livestock out
13、put used for self-consumption:the crop or livestock output used for self-supply,such as fodder,draft animal:the production of units of livestock at period t:livestock:the wage level,such as seasonal off-farm wage,constant off-farm wage hiring labor wage:the off-farm labor supply of seasonal part-tim
14、e labor or constant off-farm labor:the hiring labor supply:family labor:family labor input for farm activities:total labor input for farm activities:discount rateModules of LP ModelProcesses(73)Production(22):cropping corresponding to land typeCorn,Millet,Potato,Sunflower,Rapeseed,Beans,Goat,Sheep,H
15、og,CattleSale(11):Corn,Millet,Potato,Sunflower,Rapeseed,Goat,Sheep,Hog,Mutton,Pork,WoolSelf-consumption(6):Corn,Millet,Potato,Beans,Mutton,PorkPurchase(11):Wheat,Rice,Pork,Mutton,Beef,Vegetable,Fertilizers,Pesticide,seeds,Coal Self-supply(5):Seeds,Fodder,Manure,FirewoodResource supply(17):Land suppl
16、y(6),Labor supply(11)Land degradation(1):Soil erosionModules of LP Model-continueConstraints(70)Products(12):Resources(30):land constraints(7);labor time constraints(13);labor allocation constraints(10):family labor(3),hiring labor(7)Balance(25):Nutrition and human demand(10);Farming input(11);Lives
17、tock input(4)Rotation(2)Soil erosion(1)Land use in Ge-zhen-yan Village,Zhunger,Inner MongoliaThe policy measure of converting slope field into forest and pasture started Since 2000,with subsidy of 100kg grain and 20Yuan food-for work per 6.7aCropping system and land useTotalFlat fieldTerrace fieldSl
18、ope fieldSown areaYieldSown areaYieldSown areaYieldSown areaYieldhakg/hahakg/hahakg/hahakg/haCorn7.67 6,6604.27 9,2501.27 5,1002.13 3,750Millet6.87 1,8191.47 1,8505.41 1,808Rapeseed3.07 5802.00 6601.07 500Sunflower2.43 8850.73 1,0001.69 836Potato2.80 7,5001.07 7,1251.73 7,725Beans0.87 1,4000.47 1,50
19、00.40 1,300Total23.70 4.27 7.00 12.43 Agriculture and farm economyfarm typeunitTotalFarm householdPart-time householdhouseholdperson21129populationperson814932laborperson563422off-farm laborperson14410seasonal off-farm laborperson936constant off-farm laborperson514population per householdperson per
20、household3.86 4.08 3.56 cultivated landha per household1.19 1.43 0.87 family incomeYuan per household8,9049,6457,998farm incomeYuan per household5,9459,0182,188off-farm incomeYuan per household2,9606275,810ratio of off-farm income%33%7%73%ratio of livestock income within farm income%66%69%51%Prices
21、of agricultural productscommodityfarm gate pricesfarm purchase pricescommodityfarm purchase pricesCorn0.93 1.00 Wheat2.00 Millet0.82 1.60 Rice2.20 Potato0.50 1.00 Beef15.00 Sunflower2.00 Fish14.00 Rapeseed2.00 Vegetable1.34 Mutton8.00 14.00 Compound fertilizer2.07 Pork8.00 10.00 Carbamide1.45 Wool20
22、0 Carbon ammonia0.72 Goat240 Corn seed4.86 Sheep140 Hog800 Soil erosion:EPIC resultSoil erosion values derived from EPIC ModelField typeFlat fieldTerraceSlope fieldSlope0%5%10%Maize0.430 4.400 12.520 Millet0.550 5.620 15.770 Sunflower0.510 5.220 15.090 Rapeseed0.460 4.670 13.090 Potato0.200 2.070 5.
23、880 Beans0.460 4.670 13.090 Note:1)unit is ton ha-1.simulation results are means of ten years.2)simulation results are means of ten years.Agriculture and land use systemCrop-livestock system:corn-goat-sheep-hog.Corn mainly in flat field for feed and commercial use;millet in terrace and slope field f
24、or staple food;rapeseed,sunflower in terrace and slope field for commercial use;potato and beans for self-consumption.Field type is most important factor affecting yield.Level of input and technological choice of various crops correspond to field types.Soil erosion modulus differ between field types
25、 and various crops.Farm economy Smallholders:farm households(12)and part-time households(9).Farm households earn income from crop-livestock activity(livestock income:70%).Part-time households earn most income from off-farm activity(73%).Off-farm job opportunity is limited.Only members of the village
26、 can gain right of land management.There is few mobility of land management right.退耕还林还草政策对水土保持影响的比较静态模拟 模拟结果与现状的拟合比较农产品价格变动对土地利用变化影响的比较静态模拟结果退耕还林还草政策对土地利用变化和水土保持影响的比较静态模拟结果退耕还林还草补贴对土地利用变化和水土保持影响的比较静态模拟结果非农就业机会对土地利用变化和水土保持影响的比较静态模拟结果ComparisonbetweenactualsituationandbaserunresultsunitActualsituatio
27、nin2002BaserunTotalfamilyincomeYuan139,141194,403CropproductionCornflatmu64.00.0Cornterracemu19.07.4Cornslopemu32.00.0Feedcornflatmun.a66.0Feedcornterracemun.a53.1Feedcornslopemun.a34.9MilletTerracemu22.00.0MilletSlopemu81.146.6Potatoterracemu16.06.8Potatoslopemu26.00.0Sunflowerterracemu11.00.0Sunfl
28、owerslopemu25.460.7Rapeseedterracemu30.053.7Rapeseedslopemu16.00.0Beanmu13.020.7LivestockGoatfamilylaborhead377.0348.4Shedsheephead123.0734.9Hoghead39.00.0Grazingcattlehead4.04.0The base runHouseholds may realize a significant increase in income without increase in soil erosion if they put a much gr
29、eat weight on sedentary livestock by using maize and straws as fodder instead of selling maize to earn cash income,and change to grow much more cash crops such as sunflower and rapeseeds in stead of millet.One of probable reason of farmers self-sufficient choice is from constraint of investment.Anot
30、her probable reason is from farmers risk aversion.Price change and land degradationChanges in prices of livestock will affect livestock choice,but have no significant effects on land use choice as well as soil erosion.Changes in price ratios of commercial crops affect land use choice,especially land
31、 use choice of slope fields,and then have significant impacts on soil erosion.The effects of price change on soil erosion depend on ratio of erosion modulus between concerning crops.Off-farm job opportunity and soil erosionIncrease in off-farm job opportunities for seasonal part-time labors have few
32、 effects on land use activities.Increase in off-farm job opportunities for constant off-farm labors will influence land use choice and then land degradation.While the number of constant off-farm labors continues to increase and exceeds over 25 persons,cultivation of millet in slope fields will tend
33、to decrease.As the result,soil erosion will tend to decrease due to withdrawal of cultivation in slope fields along with an increase in off-farm job opportunities.Land conversion policy and soil erosionIntroducing land conversion policy will affect land use choice of slope fields as well as terrace
34、fields,and concomitant livestock choice,then have significant effects on reducing soil erosion.Subsidy towards converted slope fields will encourage conversion of slope fields and have significant effects on land use choice,livestock choice as well as soil erosion.Subsidy and soil erosionWhen introd
35、ucing land conversion policy without subsidy,farm income tends to decrease as a cost for combating soil erosion.While allowance of more than 160 Yuan per 6.67a was paid for farmers,soil erosion will be relieved significantly with an increase in farm income.The subsidy for converted slope fields in l
36、oess plateau includes 100kg grain with a price of 1.4Yuan per kg and 20Yuan of food-for work aid per 6.7a,which is equal to 160Yuan per 6.7a.Conclusion and implicationAn integrated bio-economic household model may simulate the effects of change in socio-economic factors on land degradation by involv
37、ing farm economic behavior within an integrated framework.Mathematical programming approach is useful to develop a bio-economic household model because it can combine farm economic behavior and biophysical process.Conclusion and implication-continueThe soil conservation program to convert slope fiel
38、ds into forest or pasture is an effective way for combating soil erosion.A reasonable subsidy as compensation that is higher than profit of land use activity of converted slope fields may encourage farmers join the conservation program and adopt of conversion activity.Conclusion and implication-cont
39、inueFarmers might go back to cultivate slope fields that have been converted into pasture when the subsidy stopped.To consolidate the achievement of combating soil erosion,how to develop alternative sectors and to increase household income after farmers converted slope fields into pasture became an
40、inevitable issue.A considerable policy is to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as fodder and forage grass from the converted slope fields.关于退耕还林政策的进一步思考退耕还林政策的巨大作用短期内促进了坡地退耕，减少了水土流失退耕还林政策的局限性恢复林草植被V.S.农地有效利用与粮食安全保障退耕地有效利用：粮食安全保障退耕还林政策补贴结束后的后续产业发展农民收入保障退耕还林与生态环境综合治理的政策选择退耕还林政策与区域可持续发展结 束 语：人文社会科学与自然科学相互融合的必要性人文社会科学与自然科学相互融合的可能性相关的研究对象人地关系与区域可持续发展人文社会科学与自然科学相互融合的必要性人文社会科学家只有应用自然科学研究成果，才能对人地关系自然生态过程及其机制有所认识应用人文社会科学研究方法，有助于在自然科学研究成果基础上，加深对人地关系动态过程及区域可持续发展策略的认识，提出政策建议Thanks演讲完毕，谢谢观看！