Abstract

Infestations of wildlands by invasive plants can reduce resource productivity, decrease biodiversity, displace native vegetation, and alter ecosystem processes and functions. The traditional reactive strategy of controlling established invasive plant infestations followed by restoration of the native plant community has proven to be largely ineffective at reducing the spread and negative impacts of invasive plants. This approach often fails in its attempt to restore native plant communities and is too costly to apply at the scale required to have substantial effects. While large amounts of resources are intensively spent on efforts to restore a few infested wildlands, invasive plants continue to spread via emerging populations and expanding established infestations. A proactive approach with the objective of preventing new infestations and limiting the expansion of existing infestations is a more effective and efficient strategy for managing invasive plants in wildlands because it precludes the need for restoration. However, relatively few resources are being directed towards preventing the spread of invasive species. Successful strategies to prevent infestations of invasive plants should focus on: 1) limiting the spatial dispersal of propagules (i.e., reducing propagule pressure), 2) maintaining or increasing the ability of wildland plant communities to resist invasion (i.e., biotic resistance), and 3) systematically searching for and eradicating new infestations. Propagule pressure and biotic resistance interact to determine wildland plant community invasibility. At low biotic resistance even a few propagules may result in successful invasion; however, as biotic resistance increases, greater propagule pressure is

Correspondence: Kirk W. Davies, USDA-Agricultural Research Service, Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, Oregon, 97720. Email: [email protected] Tel: (541) 573-4074

required for invasion. Thus, efforts aimed at decreasing invasive plant propagule pressure and increasing biotic resistance can greatly reduce new infestations. Systematically searching for and eradicating new infestations is also a critical element of a successful prevention strategy, because uncontrollable events may still lead to new infestations. Successful management of invasive plants in wildlands will require more efforts and resources directed at prevention. This task can be facilitated by more research developing and improving prevention strategies and demonstrating the effectiveness of proactive management.

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