黄土丘陵区农业生态系统产业结构与功能变化的分析和评价

以延安市宝塔区河庄坪镇为研究对象,对农业生态系统生产力、产业结构及效益进行了动态分析,结果表明:1996~2003年,该镇农业生态系统产品生产力、经济生产力均有不同程度的提高,人均产菜增长了近4.46倍,粮食与蔬菜单位面积产值分别增加了近2.7倍与1.09倍,人均纯收入增长了45.7%,达1 820.9元;种植业纯收入及其组分优势度呈升高趋势,而种植业效益却呈降低趋势;养殖业基础比较薄弱、效益低下,虽目前表现入不敷出,但因其日益受到重视,将逐渐成为继种植业后的第二大经济收入来源;果业纯收入与其组分优势度稳中有降,而果业效益在逐年提高;工副业纯收入、组分优势度及效益均呈下降趋势,并在2002年出现波谷。就农业生态系统整体而言,系统总体优势度呈上升趋势,系统稳定性指数在波动中下降,表明系统结构趋于不合理,稳定性较差,需加大对农业产业结构的调整力度。

Analysis and assessment for industrial structure and function variation of the agroecosystem in the Hilly and Gully Region of Loess Plateau

The industrial structure,function and benefit of agroecosystem in Hezhuangping town,Yan'an city were analyzed and evaluated in this paper.Results showed that from 1996 to 2003,the product productivity and economic productivity both went up in different degrees.For example,yield of vegetable per capita increased by 4.46 times.Output values of grains and vegetables were enhanced by 2.7 and 1.09 times respectively.Net income per capita increased 45.7%,reaching 1 820.9 yuan.Net income and composition priority of crop cultivation were liable to ascend,but its benefit was inclined to descend.The starting point and efficiency of aquaculture were low,and intput was more than output at present,however,it was emphasized gradually,and would become the second biggest income source next to crop cultivation.The net income and composition priority of fruit farming fell down slowly,yet its benefit went up year by year.The net income,composition priority and income-expenditure ratio of industry & sideline came down,and the lowest trough happened in 2002.From the view of whole agro-ecosystem,system total priority grew higher and higher,system stability index fell down in fluctuation,which meant the agro-ecosystem construction was not in good balance and system stability was poor.The agro-ecosystem needs more modification.