种间作用在很大程度上决定了灌草复合系统的生产力和可持续性，理解种间作用是经营和管理灌草复合系统的关键。化感作用是植物生态系统中普遍存在且值得重视的问题，它是植物间生存竞争的一种重要方式，对植物间化感作用研究已成为现代灌草复合系统建置研究的核心内容之一，也是设计灌草复合经营模式时考虑的中心问题。宁夏荒漠草原人工灌草复合系统中间锦鸡儿与紫花苜蓿竞争过程中存在的化感作用和机制及其资源竞争能力，尚不清楚。本项目通过室内模拟和野外控制相结合的试验方法，研究荒漠草原中间锦鸡儿对紫花苜蓿的化感作用，分析其化感作用阈值范围，分离和鉴定出对靶标植物的主要化感物质，辨识两者间化感作用和资源竞争效应，进而揭示其化感作用机制，为荒漠草原人工建置灌草复合系统提供理论依据和实践指导。

The productivity and sustainability of shrub-grass system depend on a large extent the interspecific interactions in the system. To understand these interactions is crucial to the successful management of shrub-grass system. The allelopathy in plant ecosystem are common and have attracted attention, because it is an important way of competition for existence between plants, so the research of allelopathy has become one of the core contents to establish modern shrub-grass system. What about the shrub-grass (Caragana intermedia-Medicago sative) system in desert steppe of Ningxia, it is unknown. The allelopathy, its mechanism and the relative importance of allelopathy in interference in Caragana intermedia-Medicago sative compound system will be studied by using the theories and methods of chemical ecology, plant ecology and agriculture ecology. The study is helpful to understand plant-plant interactions in shrub-grass system in desert steppe, and to provide the basic theory and the practice of artificial shrub-grass system.