黄土丘陵区退耕还林(草)生态经济系统的能值分析--以安塞县为例  

Emergy evaluation on ecological and economic systems of converting farmland into forest(grassland) project in loess hilly and gully areas——A case study of Ansai County

作　　者：杜英[1] 杨改河[2] 刘志超[2] 冯永忠[2] 

机构地区：[1]西北农林科技大学资源环境学院 [2]西北农林科技大学农学院

出　　处：《干旱地区农业研究》2008年第5期189-196,共8页Agricultural Research in the Arid Areas

基　　金：国家重大基础预研项目(2005CCA05300);西北农林科技大学青年骨干支持计划

摘　　要：能值分析方法是惯用的评价生态系统能量输入输出的方法之一。本文以位于陕西省黄土丘陵区的安塞县为例,通过分析该区域退耕还林(草)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(草)工程的生态经济效应。研究结果显示: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,但随着退耕还林工程的开展,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;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。Emergy analysis is one of the usually employed method to evaluate the input and output of ecosystem.Through analyzing dynamic changes of the emergy input and output before and after implementing the policy of Converting Farmland into Forest and Grassland in Ansai County located in the loess plateau area of Shaanxi Province,the ecological and economical effect of this policy is evaluated quantitatively.It is found that,influenced by the project of Converting Farmland into Forest and Grassland,both the yearly gross input and output emergy value show a increasing trend with only a little decrease in the initial period,and the organic emergy and the unrenewable environment and resources input shows a decreasing trend,which justifies that the Converting Farmland into Forest and Grassland project could have a positive effect on the maintenance of surface soil.In the total emergy output,the emergy output of planting and breading is the largest in quantitative amount.However,with the implementation of Converting Farmland to the Forest and Grassland,the emergy output of the forest begin to increase fast,and the structure of the ecosystem begin to develop in a multi-direction way.Among the main indexes of the ecosystem,emergy investment ratio and environment load ratio exhibit a trend of increasing first,then decreasing a little,and finally lasting increasing.In addition,both the emergy yield ratio and the emergy sustainable indices show a lasting increasing trend with only a little decreasing in the initial period,and the stability of the system exhibits an increasing trend.In conclusion,all those results show that after converting the farmland to the forest and grassland,the ecological pressure of the system begins to decrease,the durability begins to increase,the structure of the system becomes stable,and the system function gets harmonized.All these realize both the success in economical as well as ecological sense.

关 键 词：退耕还林 生态经济效应 能值分析 黄土丘陵区 

分 类 号：F062.2[经济管理—政治经济学]