Invasive Plants Blog Posts

This year, the San Francisco Bay Area Inventory & Monitoring Network’s Botany Team has been confronted by a tenacious trio of problematic species collectively referred to as “broom”.

Working with invasive plants is a lot like weeding a garden—if the garden is acres and acres of land, and some of the weeds are seven feet tall. In November, I went into the field with Biological Science Technician Colleen Herr to help tackle a small part of the garden that is Point Reyes National Seashore. We were looking for Scotch broom, an invasive shrub with small leaves and yellow flowers, and we had been given a heads-up that there was some nearby.

Perhaps the last thing a weed cares about is where one property ends and another begins. As part of their efforts to collaboratively care for Mt. Tamalpais in Marin County, the five One Tam partners—National Park Service, California State Parks, Marin Water, Marin County Parks, and Golden Gate National Parks Conservancy—teamed up to create an Early Detection Rapid Response program to manage weeds across boundaries. Now, the successful program is spreading across California.

Keeping invasive plants at bay is a powerful way to help native plants and wildlife flourish. But that’s no easy task when you aren’t quite sure where they are; first, you have to find them. The One Tam Conservation Management Team recently set out to do just that to help land managers keep one particular species of concern off of upper Mount Tamalpais: thoroughwort (Ageratina adenophora).

Brushing and flossing every day isn’t a glamorous task. But if you don’t do it, you risk serious dental health issues. So it is with Invasive plant surveys. They aren’t flashy, but the health of ecosystems depends on them. On Mount Tamalpais, invasive plant surveys are coordinated by the One Tam Early Detection and Rapid Response (EDRR) program. In mid-June, the EDRR program finished a second cycle of early detection surveys along Mt. Tam’s road and trail network.

By the late 1990s, two non-native, invasive plant species had invaded 60% of Point Reyes National Seashore’s 2,200 acres of coastal bluff, dune, and scrub. That prompted the park to embark on an ambitious coastal dune restoration effort starting in 2001. However, native plants have not returned to some more inland dune areas. Could soil microorganisms be playing a role? To find out, scientists compared soil microbial communities in differently invaded and restored dune areas.

Invasive plants don’t see our property lines. The five partners that make up Marin County’s One Tam partnership know this, and they teamed up to create an Early Detection and Rapid Response program tasked with identifying and managing invasives across jurisdictions on Mt. Tamalpais. With early leadership from the Inventorying & Monitoring Network’s Invasive Species Early Detection Program, crews from One Tam surveyed over 400 miles of roads, trails, and stream corridors.

As part of a collaborative effort to manage Japanese knotweed within the Lagunitas Creek watershed, a team of ecologists from One Tam’s Conservation Management Program conducted a four-week survey to map all Japanese knotweed patches in the riparian corridor on public lands. Visit their Story Map to learn more about the creek, the plant, the surveys, and why it all matters.

The 2019 issue of Early Detection News is now available. Brought to you by the Invasive Species Early Detection (ISED) Program, this newsletter has the latest on invasive plants in the Bay Area. In 2019, surveys took place between March and October at Golden Gate National Recreation Area, Point Reyes National Seashore, John Muir National Historic Site, and Pinnacles National Park.

Homeowners, land managers, and coho salmon and all share a common concern along Lagunitas Creek in Marin County: Japanese knotweed. The plant is one of the world’s most invasive species, and was first reported in the area in 2011. This year, an early round of Japanese knotweed treatments is focusing on an area along Lagunitas Creek where a coho salmon habitat enhancement project will be taking place later in the summer.