Yellow flowers of the invasive creeping capeweed in the Marin Headlands
Invasive creeping capeweed in the Marin Headlands, Golden Gate National Recreation Area.

NPS / Jessica Weinberg McClosky

Why Are Invasive Plants a Big Deal?

Invasive plants can dramatically alter ecosystems and reduce the amount of habitat available for native plant and animal species. For example, Portuguese broom not only crowds out native species, but also changes nutrient cycling and alters fire regimes. Invasive plants can also negatively impact views, trails, and structures.

The San Francisco Bay Area Inventory and Monitoring Network has developed an invasive plant early detection protocol to prioritize, find, and map invasive plants at Golden Gate National Recreation Area, Point Reyes National Seashore, Pinnacles National Park, and John Muir National Historic Site.

What Is Invasive Plant Early Detection For?

  • To find potentially problematic invasive plants before they become widely established and while they can still be easily controlled
  • To inform park-based eradication teams of invasive plant infestation locations
Chart showing that invasive plants in the parks are ranked (List 1 being the highest priority; List 4 being lower priority) based on how quickly they spread, how much damage they cause, the number of acres infested, and removal costs.
Invasive plants in the parks are ranked based on how quickly they spread, how much damage they cause, the number of acres infested, and removal costs. The rankings are represented by four different lists; List 1 contains the highest priority plants for early detection and removal efforts.

NPS / Jessica Weinberg McClosky

How Do We Use Invasive Plant Early Detection Data?

  • To determine the distribution and abundance of target invasive plant species
  • To help measure the success of invasive plant removal activities
  • To better understand how different invasive plants threaten local ecosystems
  • To re-prioritize which invasive species and sensitive locations are important to target on future early detection surveys
  • To determine the primary pathways and factors that lead to new infestations along roads and trails, and inform efforts to slow or prevent future infestations
Early detection intern Lindsay Ringer teaches volunteers to identify invasive purple foxglove.
Early detection intern Lindsay Ringer teaches volunteers to identify invasive purple foxglove. Because of the huge number of invasive plants and locations needing surveys, the early detection program would not be possible without the help of interns and volunteers.

NPS / Kevin Sherrill

What Have We Learned?

Since invasive plant early detection surveys began in 2008, NPS staff, interns, and volunteers have found invasive plants to be widespread throughout the parks. They have recorded and removed thousands of priority invasive plant populations and discovered invasive plant species new to the parks. Monitoring has also increased the information available about which species pose the greatest threats. More data is necessary, however, to identify trends in the prevalence of invasive plants and determine which environmental factors most influence their success.

For More Information

San Francisco Bay Area Network Botanist
Eric Wrubel

Links
San Francisco Bay Area Inventory & Monitoring Network
Pacific Coast Science and Learning Center

Summary by Jessica Weinberg McClosky, August 2014.
Download PDF from the NPS Data Store

Last updated: September 14, 2018