Emergy comparative analysis of different agroforestry models in _purple soil area: a case study in pear tree-crop intercropping | 紫色土区不同农林复合模式的能值对比分析

صينى. 对比分析紫色土区不同农林复合模式的结构功能特征和生态经济效益。采用能值分析理论和方法，以当地梨树林地及其林下不同作物形成的农林复合生态系统为研究对象，对紫色土区梨树-油菜-玉米(M1)、梨树-油菜-花生(M2)、梨树-小麦-玉米(M3)和梨树-小麦-甘薯(M4) 4种农林复合模式的能值投入产出进行比较。M1、M2、M3和M4 4种农林复合模式的能投结构相似，均以消耗不可更新资源为主，劳力和化肥能值占主导地位。M1模式的生产效率最高，产品在价格竞争上最有优势，独自发展能力最强；M4模式对自然可更新资源利用程度最低，自然环境负荷程度最小，能值可持续性指标最大；M2和M3模式的净能值产出率和能值自给率相近，但M2模式对环境压力小，更具有发展潜力。紫色土区农林复合生态系统的科技水平低下，应加大有机能投入。梨树-油菜-玉米模式是当前最优的一种模式，梨树-小麦-甘薯模式最具发展潜力。

إنجليزي. This study was to make a comparative analysis of structure and function characteristics and ecological and economic benefits on different agroforestry models in purple soil area. The agroforestry ecosystem, formed by pear forest and different crops planted under the local forest, was taken as the research objective. Energy analysis method was used to compare the energy input and output of pear-rapeseed-corn system (model 1), pear-rapeseed-peanut system (model 2)，pear-wheat-corn system (model 3) and pear-wheat-sweet potato system (model 4). The results showed that the energy input structure in four agroforestry models were similar. The investment of nonrenewable energy took a main proportion in the systems. The human labor energy and the fertilizer energy played dominant roles. The pear-rapeseed-corn system (model 1) had the highest production efficiency, the most advantageous in price-competition, and the most powerful self-development. The pear-wheat-sweet potato system (model 4) had the lowest renewable resource utilization, the smallest environment load ratio and the biggest energy sustainable indices. The net energy yield ratio and energy self-support ratio of the pear-rapeseed-peanut system (model 2) were close to the pear-wheat-corn system (model 3). However, the pear-rapeseed-peanut system (model 2) had higher development potential because of its lower environment pressure. The science and technology level of the agroforestry ecosystem in purple soil area was lower. The input of the organic manure should be raised. The pear-rapeseed-corn system (model 1) was the best model at present and the pear-wheat-sweet potato system (model 4) was the most potential model for development.