Exotic Invasive Plants: Integrated Pest Management at Point Reyes National Seashore
At Point Reyes National Seashore (PRNS), chemical treatment of pests is always the method of last resort. PRNS uses an Integrated Pest Management (IPM) approach, in which pesticides are selected only if other methods are unavailable or unfeasible. An IPM approach is used throughout the National Park Service. For invasive plants, methods are designed to minimize the number of return visits and to improve the likelihood of native plant establishment, so that eventually, natural areas will not need manipulation to stay weed-free. Unfortunately, some invasive plants actually spread faster if only manual methods of removal are attempted. Based on the literature, expert consultation, and professional judgment of NPS biologists, without some targeted and judicious use of herbicides, we risk losing populations of rare, endangered, and threatened plants and animals.
The Scotch broom control project is a recent example of PRNS's use of Integrated Pest Management. Scotch broom is a high-priority invasive plant that can form monocultures and crowd out all other native vegetation. It contains chemical compounds that can be toxic to native wildlife and plants and causes changes in soils and hydrology that can be ecosystem-altering. Scotch broom has been treated at PRNS using fire, heavy equipment, and manual tools since the 1990s. Our goal is to treat all known Scotch broom infestations within the park by 2014. With current funding, more than two-thirds of the 171 acres treated have been removed manually or mechanically. To stop this invasion quickly and effectively enough to protect rare species and native plant communities, PRNS staff decided to treat the remaining Scotch broom with herbicides, adhering to the following herbicide use protocols and mitigations:
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