农业生态系统是人类所控制和管理的自然-人工复合生态经济系统.农业生态系统的变化预测对区域农业生态安全和控制农业系统退化起着重要的作用.基于农业生态系统的能值分析,预测区域生态安全能够为农业生态安全提供借鉴和预警,从而可以尽早提出警报,采取措施有效地抑制、减轻、控制和规范农业生态系统的恶化,最终使农业生态系统可持续发展.本文分析了河北省武安市1997年至2008年的农业生态系统内的能量输入输出,采用灰色预测系统模型,建立了河北省武安市农田的预警系统,为农田的正确使用提供借鉴.结果表明河北省武安市农业的发展仍然依赖于非再生资源的输入和高排放的环境压力,从而使武安市农田系统处于不可持续状态.它从1997年的安全降低到2008年的预警,而且在2015年,2020年仍将处于预警的农业生态安全.此外,各区域的农业生态安全存在明显的差异.基于此,本文提出了可持续的农业发展对策,为土地使用的可持续发展提供借鉴.%Forecasting changes in agricultural ecology is important for the maintenance of agricultural ecological security and control of agricultural ecosystem deterioration. Based on emergy analysis of agricultural ecosystem, early warning study of regional ecological security identified warning condition and the importance of agricultural ecological security, so that people can make warning and alarming as early as possible and take measures to inhibit, mitigate, control and regulate it effectively before the agricultural ecosystem degradation and qualitative change, which can make agricultural ecosystem step into a vicious cycle. In this thesis, the emergy input-output and emergy based indices of farmland in Wu'an city, Hebei province from 1997 to 2008 were studied through the emergy analysis to dynamically evaluate and identify the farmland sustainability. The early warning system of Wu'an farmland with Grey Model was established for early warning of farmland use. The results indicated that Wu'an city Hebei province had more reliannce on the local non-renewable resources input, more environmental pressure and lower sustainability. It changed from no warning condition in 1997 to warning condition in 2008, and it would be consistent in warning condition in 2015, 2020 with Grey Model. In addition, the index of agricultural ecological security of each town is presented. Meanwhile, the countermeasures of sustainable agricultural development are pointed out, which can provide a basis and example for ecological regulation and control of sustainable agricultural development.
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