土地整治项目对农田生态系统影响的能值分析

为在项目尺度构建土地整治农田生态系统能值分析框架,以江苏省宜兴市土地整治项目作为案例,根据设定的土地整治工程使用年限,从项目建设-使用过程和项目全生命周期2个时间维度,对土地整治工程建设对农田生态系统的影响进行了研究。结果表明:在项目建设-使用过程维度,1)项目建设期大量物料投入和电力等资源输入,导致能值投入加大,能值产出下降;2)受土地整治影响,项目建设导致农田生态系统自给能力减弱,对外界经济投入依赖度增加,净能值产出率下降,环境负载率增大,农田生态系统可持续发展能力下降;从生命全周期来看,3)由于土地整治工程的影响,各项能值指标在项目建设期出现陡增和陡降现象,随着土地整治工程竣工以及效益发挥,各项能值开始趋于平稳,并在全周期末各项指标优于土地整治前各项指标,全生命周期内预计给农田生态系统带来2.23E+19sej能值产出和60.15万美元能值-货币价值。综合而言,土地整治在项目建成后的10年内对项目区农田生态系统具有积极影响,但此后,可能将对项目区的生态环境造成了一定的压力。

Determining the influence of land consolidation project on farmland ecosystem based on emergy analysis

In order to build an emergy analysis framework of land reclamation farmland ecosystem from the project scale,a case study in Yixing City of Jiangsu Province land reclamation project was conducted in this study.According to the durable years of land reclamation project,ecological influences on farmland ecosystem were investigated from two points of view,whole process of project and the total project life cycle.The results showed that:From the whole process of project dimension,a large number of materials and electric power resource input during project construction period resulted in increase of input emergy and decrease of output.Affected by the land reclamation,the construction of project caused the decrease of self-sufficiency,emergy yield ratio and emergy sustainable index of farmland ecosystems,the increase of dependent degree on external economic investment and environment loading ratio;From the total project life cycle dimension,the emergy indexes during project construction displayed sharp and steep fall phenomenon.With the completion and benefit of the land reclamation project,the emergy indexes reached a plateau,and in the end of the whole cycle indicators are better than those before land reclamation.Emergy input of 2.23E+19sej and EM $ of 601 500 dollars were predicted to bring to the region during the total project life cycle.In conclusion,land reclamation within 10 years after the completion of the project has a positive influence on the project of farmland ecosystem,but may cause certain level of pressure on the ecological environment.