【作者】 杜英；

【导师】 杨改河；

【作者基本信息】 西北农林科技大学 ， 生态学， 2008， 博士

【摘要】 退耕还林作为一项长期的、复杂的生态工程,其在改善局部生态环境的同时,也会影响到退耕区的社会经济的发展,而退耕区的经济发展水平直接关系着退耕还林工程的持续性发展。采用科学的评价方法对退耕还林工程实施以来的退耕区农户的生产、生活状况及退耕区的社会经济发展水平进行研究,科学评价退耕还林工程所产生的生态效应和经济效应,并对二者之间的耦合协调状况进行评判,是当前关于退耕还林的研究工作中迫切需要解决的现实问题,同时也是保障退耕还林生态系统和谐健康、持续发展的理论基础。本文以黄土丘陵区的退耕还林典型县域安塞县为具体研究对象,从退耕还林工程对退耕区的生态环境与社会经济影响的描述性分析入手,以能值理论为基础对退耕还林工程的生态经济效应进行了定量的评价,并运用耦合协调度模型分别对安塞县退耕前后生态系统耦合协调状况和安塞县小区域范围内不同退耕模式的系统耦合协调状况进行了定量性的研究。主要研究结果如下:⑴退耕还林工程对生态环境的影响本文用农田生态系统转变为林草生态系统服务价值的增加量来体现退耕还林工程的生态效益。运用生态经济学原理和生态系统服务价值核算的理论与方法,根据退耕还林工程实施前后生态系统特征的变化和生态系统服务的内涵,选取土壤保持、涵养水源、维持营养物质循环、固碳释氧、净化空气、保护生物多样性等指标,运用市场价值法、费用替代法、影子工程法、机会成本法等方法系统研究了退耕还林工程生态系统服务功能及价值的时空变化,并对退耕后生态系统各植被类型的服务价值进行了评估。结果表明:安塞县退耕还林工程使生态系统总服务价值从退耕前(1998年)的188.37亿元,增加到退耕后(2005年)的241.03亿元,增幅达27.95%;在生态系统各项服务功能价值的贡献之中,涵养水源价值量最高(77.08%),接近于总价值的3/4,其次是土壤保持价值(11.43%)、维持营养物质循环价值(6.83%)及固碳释氧价值(3.94%),最低的是保护生物多样性价值(0.54%)和净化空气价值(0.18%);实施退耕还林工程后各植被类型总服务价值顺序为:灌木林>草地>乔木林>经济林;从各植被类型的单位面积系统服务价值量来看,系统服务功能大小依次为:乔木林、灌木林、草地、经济林、农田。实践证明退耕还林工程的实施在保护环境,治理水土流失方面具有显著的作用。⑵退耕还林工程对社会经济的影响采用参与性农户评估方法,根据安塞县地理地形和自然条件的特点将研究区按照北部、中部和南部三个区域对290户退耕农户进行了分层随机抽样调查。对退耕还林工程实施以来,退耕区的粮食安全、经济收入,农村劳动力转移、农业产业结构调整及退耕农户的消费结构等5个方面的变化进行了分析。结果显示:退耕还林的实施带来了耕地面积的下降及粮食总产量的降低,但粮食单产在退耕后实现了稳中有升的发展态势,同时退耕还改变了以往单一的以粮食作物为主的种植方式;退耕后实现了农民收入的增加,并带来了收入结构的改变,使农民的收入来源日趋多样化;工程的实施产生了大量的剩余劳动力,但大部分是以隐蔽性的失业状态存在;退耕农户在退耕后的消费结构得到了一定的改善,食品支出在总消费支出中的比重有所下降,医疗、教育、通讯等方面的支出有所提高,在生活能源消费方面,过去以作物秸秆为主要燃料的现象逐渐得到改善,煤炭、煤气、沼气等能源被农户所使用,农户的燃料结构正在趋向多元化方向发展。⑶退耕还林工程生态经济效应研究本文应用美国著名生态学家H.T.Odum创立的能值理论和方法,以安塞县为例,通过分析该区域退耕还林实施前后生态系统投入产出的能值动态变化,定量评价了退耕还林工程的生态经济效应。研究结果表明:受退耕还林工程的影响,安塞县生态系统年总投入能值和总输出能值均呈先下降后上扬的发展趋势,其中有机能和不可更新环境资源投入量表现出递减的趋势,说明退耕还林工程对于减少表土流失具有积极的作用;在总能值产出中,种植业和养殖业的能值产出占绝对优势,但随着工程的开展林业的能值产出表现出快速的增长势头,系统的结构日趋多元化方向发展;在系统主要能值指标中,能值投资率、环境负载率呈现先增后降再增长的趋势,净能值产出率和能值持续性指数均呈先降低再增长的趋势,系统稳定性呈现增加的趋势。说明退耕还林后系统的生态环境压力趋于减小、持续性增强,系统结构趋于稳定,系统功能协调,基本可以实现生态和经济双赢的目标。⑷退耕还林生态系统耦合研究在大量的实地调查和分析的基础上,采用耦合协调度模型对县域尺度的退耕还林生态系统耦合协调性以及小区域不同退耕模式的系统耦合协调性进行了定量分析,判断了当前安塞县退耕还林生态系统所处的耦合协调状况,并从权重和指标变量两个角度对其结果的敏感度进行了研究。研究结果为:安塞县退耕还林生态系统的耦合度和耦合协调度在逐年增加,系统的耦合协调状况正在得到逐步改善。但是,目前安塞县退耕还林系统的耦合协调状况还不十分理想,基本还是处于失调衰退和过度发展的时期,耦合协调类型都处于生态损益(滞后)型。关于对安塞县的六种退耕模式及对照模式的系统耦合协调性的评价结果则表明:六种模式的系统生态环境综合指数与经济发展综合指数在全体模式中的位置并不完全一致,模式A在两项指标中均位居第一位。在恢复生态环境方面,各模式均好于对照模式;在经济发展方面,模式A、B、C高于对照模式,而模式F、D、E低于对照模式。对于系统耦合协调状况的评判结果为六种退耕模式的系统耦合协调度均大于对照,而A模式的耦合协调度是六种模式中最高的。本研究的主要创新之处是:⑴将退耕区的经济社会发展因素同其生态效应结合起来,对退耕还林耦合系统的结构、功能、特性及系统耦合的程度和驱动力的系统性进行定性和定量的研究,评价了退耕还林工程的可持续性,在退耕还林工程的可持续性研究上尚属首次,该研究亦对生态系统耦合理论的系统性和完整性进行了有益的补充,丰富和完善了生态系统耦合研究的理论体系,在理论创新方面具有较大的意义。⑵在研究方法上,运用能值理论与方法对退耕还林工程的生态经济效应研究尚属首次。通过运用能值理论对退耕还林工程生态经济效应的评价,可以真实的反映退耕还林后系统内生态环境与经济发展的关系,明显提高了评价结果的可靠性和现实性,对于退耕区生态环境的科学评估与合理利用及社会经济的发展方针的制定,具有重要的理论指导意义。⑶首次提出退耕还林系统耦合的概念和理论,并运用耦合协调度模型,从县域中尺度及不同退耕模式的小区域尺度两个方面,对退耕还林生态系统的耦合度和耦合协调度进行了计算,并对当前退耕还林生态系统耦合协调的状况及所处的耦合协调类型进行了判断。引入了模型权重和指标变量值的敏感性分析,提高了判断结果的可靠性和预测力。更多还原

【Abstract】 As a continuous and complicated ecological project, converting farmland into forest and grassland will locally influence the social and economic development as well as improving the ecological environment conditions, which inversely has great importance with the project’s sustainable development. Now the problems that need to be urgently resolved, which meanwhile are the theoretical foundations of the conversion ecosystem’s harmonious and sustainable development, mainly include researching the local livelihood and the social and economic development conditions with scientific methods, evaluating the ecological and economic effects of this project and most importantly, the coupling conditions of the two effects.Choosing Ansai County as the research location, the paper started with the descriptively analysis of the ecological and economic influence of local conversion project, and then quantitatively evaluated the ecological and economic effects based on the energy value theory, at last, by establishing the coupling degree model, the paper quantitatively evaluated the ecosystem’s coupling conditions under different conversion patterns. The main results of this research could be concluded as follows:(1) Ecological effects of converting farmland into forest and grassland projectIn this paper the ecological benefit of the project was represented by the increase of ecosystem service value from the conversion of farmland into forest and grassland. According to the theories and methods of ecological economy and ecosystem service value and based on the actual situation of research location, six indexes, including soil conservation, water storage, nutrition circulation, assimilation of CO2 and O2 release, air purification and biodiversity protection, were adopted to measure the spatiotemporal changes of ecosystem service function and value combined with a series of scientific methods, also the service value of different vegetation type were evaluated. The results indicated that the total ecosystem service value of Ansai County increased by 27.95 percent, from 18.837 billion yuan in 1998 to 24.103 billion yuan in 2005; the service value of water storage was the highest, nearly accounted for 75 percent of total ecosystem service value, then followed by the soil conservation(11.43 percent), nutrition circulation(6.83 percent), assimilation of CO2 and O2 release(3.94 percent), the service value of biodiversity protection and air purification were much lower, only 0.54 and 0.18 percent of total ecosystem value; of all the vegetation types, shrub forest had the highest service value, then the grassland, arbor forest and economic forest; as to the per unit area service value, the sequence were arbor forest, shrub forest, grassland, economic forest, cropland. As a conclusion, converting farmland into forest and grassland has great significance in environment protection, mainly by controlling the water and soil erosion.(2) Social and economic effects of converting farmland into forest and grassland projectAccording to the geographic and social situations, the research location was divided into three regions and a total number of 290 peasant households were chosen randomly and investigated on food security, economic income, rural labor transfer, agricultural industrial structure adjustment and consumption structure. The analysis of the investigation indicated that although the cultivated area and the total grain yield both decreased because of the conversion, the grain yield per hectare increased steadily, and the single cultivated structure of crops was changed, too; peasants’income increased a lot and the income source was widened; A large number of surplus labor was generated and most of them were under the condition of concealed unemployment; the consumption structure was changed mainly on the decrease of food expenditure and the increase of medical, education and communication expenditure, and as for the energy consumption, the crop straw, used to be the dominant rural energy, was gradually replaced by coal, natural gas and biogas, which indicated that the energy structure of peasant household was much more reasonable and abundant.(3) Ecological and economic effects of converting farmland into forest and grassland projectBased on the theory and method of energy value established by H.T.Odum, a famous American ecologist, the research quantitatively evaluated the conversion project’s ecological and economic effects in Ansai County through analyzing the dynamic change of ecosystem energy value. The results showed that both the total input and output energy value deceased first and then increased, of which the decrease of organic energy input and primary environmental resource input reflected the project’s positive effect of controlling surface soil loss; the energy value of planting and animal husbandry industry used to be dominant in the total energy value output structure, but after the conversion, the energy value output of forestry industry increased rapidly; as the energy value indexes were mentioned, both the energy value investment ratio and environment loading ratio increased first and then decreased and increased again, pure energy value output ratio and energy value sustainability index first decreased and then increased, and the system stability was always increasing. The decreasing environment pressure, increasing ecosystem sustainability and stability and harmonious system function showed that the conversion project’s ecological and economic purpose could be basically fulfilled.(4) Ecosystem coupling research of converting farmland into forest and grassland projectBy establishing the coupling degree model, the conversion ecosystem’s coupling conditions under different conversion patterns were quantitatively evaluated and the sensitivity of the evaluation results was analyzed from two aspects, weight and index variable. The results indicated that although the ecosystem’s coupling condition was gradually improved, the coupling situation in Ansai County was still not so good, basically in the stage of recession and over development.The coupling evaluation of six different conversion patterns and the control pattern showed a different result according to the comprehensive index of ecological environment and economic development, and pattern A was the best in both two indexes. Each pattern was higher than the control pattern in ecological environment index, but as for economic development, pattern A, pattern B and pattern C were higher than the control pattern while pattern D, pattern E and pattern F was lower than that. The coupling degree of all the six conversion patterns was better than that of the control pattern and pattern A was the best.The innovation points of this research:(1) The research combined the social and economic development factors with ecological effect of converting farmland into forest and grassland project, quantitatively and qualitatively analyzed the structure, function, characteristic, coupling degree and driving force of conversion ecosystem and evaluated the sustainability of the conversion project, which used to be a blank field, also the research enriched the theory system of ecosystem coupling and has great importance in theoretical innovation.(2) Few research using energy value theory and method to evaluated ecological and economic effects of converting farmland into forest and grassland project, which could clearly reveal the relationship between ecological environment and economic development and provide much more reliable and practical evaluation results, so this paper has great theoretical guiding significance in scientifically evaluating the ecological environment conditions, reasonably utilizing natural resources and establishing guideline for social and economic development in the conversion regions.(3) The paper introduced the conception and theory of conversion ecosystem coupling for the first time, quantitatively evaluated the conversion ecosystem’s coupling conditions in county level and conversion pattern level by establishing the coupling degree model and the sensitivity analysis from weight and index variable greatly improved the reliability and prediction capability of the evaluation results.更多还原