沛县蔬菜生态系统能值分析

Emergy analysis of vegetable ecosystem in Pei County,Jiangsu Province

能值分析理论是基于"任何形式的能量都来源于太阳"这一前提,因此可将不同种类、不可比较的能量转换为同一标准,即太阳能焦耳来进行比较。本研究应用生态系统能值分析理论与方法,以江苏省蔬菜主产区之一的沛县为例,采用一系列能值指标,定量分析了该县蔬菜生态系统的环境资源基础和经济特征,为合理开发沛县蔬菜资源,实现沛县蔬菜可持续发展提供科学依据。结果表明:2007年沛县蔬菜生态系统能值投入为1.22×1021 sej,其中工业辅助能为7.18×1020 sej,占58.85%,说明沛县蔬菜产业发展主要依靠工业辅助能,已走出传统农业靠自然条件发展的阶段。沛县蔬菜生态系统能值产出为3.20×1021 sej,占农业总产出能值的39.65%,说明蔬菜产业已成为沛县农业的重要支柱产业之一;其中,茄果类和根茎类蔬菜能值产出较高,分别占蔬菜能值产出的35.63%和23.63%,而特种创汇蔬菜牛蒡和山药为蔬菜能值总产出的18.61%。沛县蔬菜生态系统能值自给率为2.67%,低于江苏省耕地生态系统(10.12%),说明环境资源已不是蔬菜发展的主要决定因素,沛县蔬菜生态系统抵抗自然灾害的能力较强;沛县蔬菜生态系统的工业辅助能值比率为58.85%,低于江苏省耕地生态系统工业辅助能比率(73.16%);沛县蔬菜生产的化肥使用量较高,占工业辅助能的69.42%,不利于蔬菜产业的可持续发展;不过沛县生态系统的有机辅助能比率为38.61%,高于江苏省耕地生态系统有机辅助能比率(16.72%);沛县蔬菜生态系统的购买能值比率为97.54%,高于江苏省耕地生态系统购买能值比率(89.88%),表明沛县蔬菜产业发展几乎完全依赖于来自社会经济系统的购买能值,而较高的购买能值促进了沛县蔬菜产业的迅速发展;沛县蔬菜生态系统的能值投入率为36.61,高于江苏省耕地生态系统能值投入率(8.88),说明沛县蔬菜产业发展迅速;但净能值产出率仅略高于江苏省耕地生态系统净能值产出率,可能由于能值产出较高的先进技术推广不够;沛县蔬菜生态系统环境负荷率为1.43,低于江苏省耕地生态系统环境负荷率(2.83),且农药能值投入仅占0.21%,说明沛县蔬菜产业有较强的可持续发展能力和较大的发展潜力。为促进沛县蔬菜产业综合效益的提高和可持续发展,应进一步加强蔬菜产业基础设施及蔬菜产品加工业的建设,加大蔬菜产业的科学技术推广力度,增强沛县蔬菜生态经济系统的产出能力。

The theory of emergy analysis is based on the premise that all forms of energy are from the sun.Different and incompa-rable forms of energy are therefore unifiable into solar emjoules.In this study,environmental resources and economic characteristics of vegetable ecosystems in Pei County（one of the main production bases of vegetable in Jiangsu Province） were quantitatively ana-lyzed using the theories and methods of ecosystem emergy analysis.A series of emergy indices were developed for evaluating the environment resources and development characters of the vegetable ecosystem in Pei County.These indices simultaneously provided scientific basis for sustainable development of vegetable industry in Pei County.The study showed that： in 2007,vegetable emergy input in Pei County was 1.22×1021 sej.Industrial auxiliary energy input was 7.18×1020 sej,accounting for 58.85% of the total vegeta-ble ecosystem emergy,which suggested that the development of vegetable industry in Pei County relied mainly on industrial auxil-iary energy,and had developed beyond traditional agriculture relied mainly on natural conditions.Vegetable ecosystem output in Pei County was 3.20×1021 sej,accounting for 39.65% of total agriculture emergy yield,indicating that vegetable industry was one of the strongest pillars of industries in Pei County.Emergy outputs from solanaceous fruits and roots,tuber vegetables were relatively high-er,accounting for 35.63% and 23.63% of total vegetable emergy yield,respectively.Foreign exchange earning vegetables such as burdock and Chinese yam accounted for 18.61% of total vegetable emergy yield.Emergy self-sufficiency ratio of vegetable ecosys-tem in Pei County was 2.67%,which was lower than that of arable land ecosystems of Jiangsu Province（10.12%）,illustrating that environmental resources were no longer the main determinants of vegetable development.The resistance of vegetable ecosystem in Pei County to natural disasters was sufficiently strong.The proportion of industrial auxiliary emergy of vegetable ecosystem in Pei County was 58.85%,which was lower than that of arable land ecosystems in Jiangsu Province（73.16%）.There was a huge consump-tion of chemical fertilizers in vegetable production in Pei County,accounting for 69.42% of industrial auxillary emergy.This was considered unfavorable to sustainable development of vegetable industry in the county.Organic auxiliary emergy ratio of vegetable ecosystem in Pei County was 38.61%,which was higher than that of arable land ecosystems of Jiangsu Province（16.72%）.Pur-chased emergy ratio of vegetable ecosystem in Pei County was 97.54%,which was higher than that of arable land ecosystems of Jiangsu Province（89.88%）,suggesting that the development of vegetable industry in Pei County almost totally depended on buying emergy of the socio-economic system.The high emergy purchase promoted rapid development of vegetable industry in Pei County.Emergy investment ratio of vegetable ecosystem in Pei County was 36.61 and that of arable land ecosystems in Jiangsu Province was 8.88.This further suggested a rapid development of vegetable industry in Pei County.However,net emergy output ratio of vegetable ecosystem in Pei County was only slightly higher than that of arable land ecosystems in Jiangsu Province.This was due to insuffi-cient promotion of high output new technologies.Environmental loading ratio of vegetable ecosystem in Pei County was 1.43,which was lower than that of arable land ecosystems in Jiangsu Province（2.83）.Pesticide input only accounted for 0.21%,indicating that vegetable industry in Pei County was strongly sustainable with a high development potential.Further strengthening of vegetable in-dustry infrastructure would enhance comprehensive benefit and sustainable development of county-level vegetable industry.It was also recommended that the development of vegetable processing industry and popularization of science and technology should be enhanced,which could benefit emergy output increase of vegetable ecosystem in Pei County.