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北方农牧交错带农业生态系统生产力分析评价及实证研究

The Evaluation and Cases Studies on the Productivity of Agroecosystem in the Ecotone between Agriculture and Pasture in North China

【作者】 董孝斌

【导师】 高旺盛;

【作者基本信息】 中国农业大学 , 作物栽培与耕作, 2003, 博士

【摘要】 北方农牧交错带生态恢复与农牧业生产之间的长期不协调性是制约该区域可持续发展的根本原因。该论文的研究目的就是在典型案例研究基础上,分析讨论农牧交错带农业生态系统生产力以及区域农业可持续发展问题。论文的主要进展归纳如下: (一)本文创造性地提出了由区域初级生产力、次级生产力、农户经济生产力以及生态系统服务生产力四部分组成的农业生态系统生产力分析框架模型及评价指标体系。首次引入了能值(emergy)分析方法和生态系统服务(ecosystem service)价值测算方法并进行了修正,这在同类研究方法上是一种具有创新意义的尝试。 (二)分析结果表明: (1)整体上该区域系统初级生产力水平已经有了较大幅度提高。以能值表示的总产出能值,安塞县2000年比1990年高34.5%。武川县同比增长36.1%。但是,初级生产依然是处于低投入的传统生产阶段。工业辅助能值的投入虽然有所增加但占能值总投入的比例不到10%,系统的净能值产出率低下。 (2)区域的次级生产力发展较快,但案例研究表明,农牧系统相互耦合机制尚未形成,农牧业整体上仍处于非协调发展时期。主要表现为两种典型结构模式,一种以安塞县为代表,农牧能值总体利用率较高,但畜牧业内部结构偏重食粮动物使得高质能转化率低下;另一种以武川县为代表,农牧业结构总体上朝趋于协调方向发展,但畜牧业规模过大,由于草畜平衡严重失调,导致农牧系统耦合机制难以稳定。 (3)安塞县和武川县农业生态系统服务价值分别是其系统产品价值的170倍和151倍,说明即使在生态环境脆弱地区,其生态系统服务也是客观存在的,且价值巨大。但是,区域的水土保持服务功能还很低下,安塞县、武川县水土保持价值占总服务价值的比例分别为5.1%、0.7%,纸坊沟流域则达到60.3%。 (4)该区域农户的实际收入水平有了一些提高,该地区农户系统的能值投入水平低下,其收入的增长是建立在对环境的巨大压力之上。不同尺度系统内农业人口超过了可更新环境资源能值可承载能力下限,安塞实际人口超载2.4倍,武川超载4.5倍,纸坊沟超载6.2倍。 (三)从长远来看,要实现该区域的系统耦合并获得系统生产力的提高,区域发展政策必须进行大的调整,具体建议:在初级生产力的植被建设上,采取草、灌优先发展对策;在农田与非农田关系上,要尤其注重基本农田的生态改良与生产力培育,提高其经济产出;在种植业与畜牧业的关系上,改变“宜农则农,宜牧则牧”的传统模式,提倡“为牧而种,因种而牧”的协调发展模式;在区域开发与农户关系上,必须始终确立农户经济生产力是系统生产力之核心的生态经济原则;在生态植被建设与功能恢复策略上,将保护农业生态系统的多项服务功能纳入政府决策框架和公众生态意识之中。

【Abstract】 The long-term incompatibility between ecosystem restoration and production of agriculture and animal husbandry in ecotone of North China is the radical reason hampering its sustainable development and to found the coupling mechanism of agriculture and animal husbandry system for advancing the agro-ecosystem productivity seems to be the ideal way of its developing harmoniously. The aim of this paper is to evaluate the actual ecosystem productivity and discuss the regional developing issue of the ecotone based on the typical case study with some prevalent approach. The region for cases studies includes two typical counties, Ansai county of Shaanxi province, Wuchuan county of Inner Mongolia, one watershed named Zhifanggou located in Ansai county with over 20 yrs artificial comprehensive ecological harness, and two different farmers household .The results are as follows.1. This paper first puts forward the framework of agro-ecosystem productivity constituted by primary productivity .secondary productivity .economic productivity of peasants household , ecosystem servicesproductivity and their evaluation indices, in which the approach of emergy analysis and ecosystem service was introduced and applied after being revised. This framework of agro-ecosystem productivity evaluation is expected to be an innovative attempt comparing to the similar research method before.2. The emergy evaluation results show that (1) The primary system productivity have risen greatly since 1990 in this region. As far as total emergy output ,Ansai county increased 34.5 percent in 2000 than in 1990,and Wuchuan county increased 36.1 percent in 2000 than in 1990,however, the primary productivity was still in the stage of traditional lower input. The emergy of industrial auxiliary energy increased but its percent in total input was less than 10 percent .The input of manpower emergy was above 60 percent of the total emergy input, and the non industrial emergy input was above 90 percent of the total emergy input. So, the net emergy yield ratio was lower, and the average ratio of emergy output to emergy input was less than 1.0. (2) The secondary productivity increases quickly in this area, however the effect of coupling between agriculture and animal husbandry is poor. The radical reason of lower ecosystem productivity and disharmonic developing in this ecotone is the improper configuration inner animal husbandry for example of Ansai county and big animal scale exceeding the threshold of the primary productivity for example of Wuchuan county, which above-mentioned leads to the fact that coupling mechanism between agriculture and animal husbandry system has not been established, and agriculture and animal husbandry is still in the state of disharmonic on the whole.3. With respect to the ecosystem service, the results show that the value of ecosystem service of Ansai county and Wuchuan county is 170 times and 151 times of their product value respectively, which reveals that even in fragile area the ecosystem services are do existed and have great value, mat definitely could provide important support to the strategy of restoring vegetation whereas reducing field for raising system productivity. However, the service function is poor and is not consistent with our expecting. The value of containing soil and water is only 5.1 percent and 0.7 percent in total ecosystem value respectively in Ansai county and Wuchuan county, however in Zhifanggou valley the ration gets to 60.3 percent. So some measures of increasing the vegetation and strengthening the service function should be taken continuingly.4. The practical income of farmers increases to some extent, but the emergy analysis of typical peasant household shows that the emergy input is in lower level with the fact of the imbalance existed in grass and animals of peasant household and overloading severely in animal husbandry. Their income is based on the great pressure to the environment. Population in different scale all exceeds the lower limit of carrying capacity of renewable re

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