Allelochemical Control of Non-Indigenous Invasive Plant Species Affecting Military Testing and Training Activities

Allelopathy is a relatively controversial concept in the ecological literature as it is hard to quantify in the field. Interest in allelopathy has increased in recent years with reports of invasive plants using allelopathy as an invasion mechanism. The present project aimed to understand this process under a variety of conditions including natural habitats and to utilize this basic knowledge in strategies to control invasive plant species affecting military testing and training. We reasoned that greater knowledge of allelopathy in the context of invasion biology could lead to more sustainable measures of invasive plant control and management. In a series of studies we characterized new allelochemicals produced by a variety of invasive plants. We screened large numbers of native plants for resistance to allelochemicals, and in the process highly competitive species were identified. Additionally, we tested new ideas about using native allelopathic smother crops against invaders. The selection of native plant species capable of establishing within invasive plant infestations was a modest success as shown in greenhouse and field studies. The project also generated basic knowledge to contribute to the ecological literature by demonstrating that allelopathy is a conditional biological occurrence and that certain biological or environmental triggers must exist to make allelopathy apparent in the field. Similarly this project has contributed basic knowledge on the plasticity of invasive species and how their intrinsic biochemistry related to defense and aggression invasion is control by the presence of other neighboring individuals. These basic and applied studies and others described in this report are likely to hold promise for more fully understanding and managing plant invasions.