论华北农牧交错区退耕区域生态系统生产力的演替与增进机制

 【目的】讨论华北农牧交错区以退耕为特征的生态系统生产力的演替与增进机制，为区域保持持久生态恢复和经济发展的动力提供思路和技术依据。【方法】采用实证研究和理论分析相结合的方法。【结果】在退耕后的生态系统中，退耕子系统的生物生产力比农作子系统降低38.34%～72.3%，其主要功能应偏重社会性的资源环境生产力，使理想中的“退耕-还草-养畜-赚钱”的良性循环难以实现。伴随退耕子系统的分化，农作子系统在自然与社会资源等方面汇集叠加，为退耕区域生态系统启动经济生产力新属性的阶跃奠定了基础。实证研究表明，通过退耕子系统与农作子系统的再度耦合，以及通过同田块创造以水肥为中心的微域生境分化与作物生产耦合，可使系统经济生产力提高8.85～13.35倍。【结论】退耕后生态系统的结构重建与开放运行，发挥市场经济下区域间互补性合作生产优势、建立开放式农牧生产结构，是华北农牧交错区系统生产力增进的重要机制。

Succession and Enhancement Mechanism of Ecosystem Productivity in the De-farming Regions of the Ecotone Between Agriculture and AnimaI Husbandry in North China

Abstract: 【Objective】The succession and enhancement mechanism of the ecosystem productivity with the characteristics as de-farming in the ecotone between agriculture and animal husbandry of North China was discussed, in order to offer a way or technical basis for maintaining the permanent impetus of ecological recovery and economy development of the region. 【Method】Cases study in combining with theoretical analysis was adopted. 【Result】 In the regioin, after de-farming the biomass productivity of de-farming subsystem decreased by 38.4%~72.3% as compared with that of farming subsystem in the ecosystem, the main function of de-farming ecosystem should be focused on social resource-environment productivity, it caused the ideally beneficial recycling that was “de-farming-planting grass-raising animals-grain money” difficult to be realized. With the de-farming subsystem differentiation, the natural and social resources in the farming subsystem were accumulated, it laid basis for starting to upgrade the new characteristic of economic productivity. Case study showed that the system economic productivity was increased by 8.85~13.35 times due to re-coupling of the de-farming subsystem and farming subsystem, as well as coupling of crop production in the combined subsystems where existed the created microhabitat differentiation of water and fertilization that were the main concepts of the differentiation in the same field. 【Conclusion】 Structure rebuilding and opening operation of the de-farming ecosystem, playing the advantage of complementary co-operative production among different regions under conditions of the market economy, and rebuilding opening agricultural production structure were the important mechanism to enhance the system productivity in the ecotone between agronomy and animal husbandry of North China.