Exotic Invasive Plants: Choosing Our Battles
The goal of the National Park Service is to preserve and protect land, resources, and native ecosystems in their natural state. Unfortunately, it is often very difficult to fully restore native communities due to the severity of changes in soil and community composition, structure, and function caused by plant invaders. Of the almost 900 plant species in the park, about 300 are non-native, with about 10% of the non-native species being both problematic to our ecosystems and feasible for management with current methods.
By necessity, management of invasive vegetation at Point Reyes National Seashore focuses on species that most seriously threaten native habitats, wildlife, and endangered plant and animal species, and are the most feasible targets for eradication efforts. Ideally, removal and containment efforts are focused on species when their populations are still small, but if a species is established in a remote area, its presence may not be noticed until the population, and the problem, is large. Vegetation management personnel work to map and prioritize target species in the park. Several invasive species are too widespread for total control to be possible. In these cases, priority for control is given to high-value areas, such as the Lighthouse or Abbotts Lagoon areas, where rare dune plants and plant communities still maintain a fragile foothold. Top priority species and/or populations are removed when there are enough resources to do so, and sites are revisited to prevent the weeds from reestablishing themselves. Visit our Abbotts Lagoon Coastal Dune Restoration Project page to learn about a recent large-scale removal of European beachgrass (Ammophila arenaria) and iceplant (Carpobrotus spp.) near Abbotts Lagoon.
Treatment of invasive plants can be very costly. For instance, in FY2009 the National Park Service received a $20 million increase for treating invasive populations and reintroducing native plant species (NPS 2008). Thus, preventing invasions from occurring and spreading, and responding rapidly while infested acres are small, is essential. It is also crucial to quantify removal costs and subsequent results, and to use resources for cost-efficient control methods in the highest-value areas. As invaders do not respect the complicated jurisdictions of Marin's many land management agencies, partnership among the agencies is required to understand distributions, recognize new invaders, prioritize effective treatments, and work with our communities to prevent infestations. One such partnership is the Marin/Sonoma Weed Management Area.
Continue reading: Integrated Pest Management at Point Reyes National Seashore