黄土高原家庭农业生态系统结构特征的分析

以黄土高原川塬灌区19个家庭农业生态系统为研究对象，采用主成分分析、逐步聚类分析和多元回归分析，对家庭农业生态系统的结构功能进行比较。结果表明，川塬灌区家庭农业生态系统可分为综合型、农牧型、农副型、农林型4种类型，反映家庭农业生态系统的结构条件主要因素为投入畜牧业子系统的资金，单位面积投入氮素，草食家畜占家畜总数百分比，粮食作物占耕地面积百分比，单位面积投入辅助能，反映家庭农业生态系统的功能的主要因素为人均产值、初级产品太阳能利用率、养殖业能量产投比、粮食总产量、羊单位总数。

Structure characteristics of the household agri-ecosystem in the Loess Plateau

In this paper, the structure characteristics of 19 samples of household agri-ecosystems in the Loess Plateau summarized by means of principal component analysis and cluster analysis. The results indicated that these household agri-ecosystems could be divided into four types:comprehensive type, agri-livestock type, agri-sideline type and agri-forestry type. The principal factors that reflect the structure characteristics of the household ecosystems are as capital invested in the livestock subsystem, nitrogen input per hectare, percentage of the ruminants among the total animals, percentage of the cereal crop areas of cultivated lands, and subsidy energy input per hectare. The function of the household ecosystem can be reflected mainly with such factors as the output value per person, the efficiency of usage of solar energy in the primary production, the ratio of output to input of the livestock subsystem, total crop yields, total crop yields, total sheep units.