To the untrained eye, the hills surrounding Contra Costa County are covered in beautiful yellow flowers. To an ecologist, this view would be alarming. Knowing these flowers to be invasive wild mustard and yellow star-thistle, an ecologist may be overwhelmed with a sinking sense of dread as they look upon this sea of invasive plants.

Invasive plants threaten the health of our ecosystems by replacing the native plants that have co-evolved with local wildlife for thousands of years. Invasive plants are non-native, meaning they were introduced to the land by humans. They become invasive once they begin to outcompete native plants for space due to their favorable adaptations in our climate. A common invasive plant in Contra Costa County is Himalayan blackberry. The vines of Himalayan blackberry can grow into thick brambles that encroach on the space of native plants.

Invasive plants can disrupt important relationships between native plants and native insects. Certain native insects rely solely on one plant for survival. For example, the Lange’s metalmark butterfly is entirely dependent on naked stem buckwheat in each life stage, from larva to adult. Imagine if an entire patch of naked stem buckwheat became overgrown with Himalayan blackberry: the population of Lange’s metalmark butterfly would decline, and an important pollinator would be lost in that area.

In habitat restoration work, invasive plant control is a key component to rehabilitating disturbed landscapes. At one CCRCD restoration site in Brentwood, a dense wall of Himalayan blackberry used to envelop the native willows and cottonwoods. Using resources provided by organizations like the California Invasive Plant Council (Cal-IPC), our restoration team implemented a management plan to control the blackberry. Now that these dense patches are gone, we are focusing on native plantings as a way to outcompete blackberry re-establishment.

Oftentimes, it may seem like invasive plants have “taken over,” but native plants still exist, tucked away in pockets, and with a little help, they can continue to thrive. Next time you find yourself hiking the hills of Contra Costa County, examine the plants around you. If you happen upon a native plant, take a moment to appreciate its ancient connection to the land.