Staff portrait for Irina Kogan.
By ,
Director of Landscape Conservation

An invasive plant in the Santa Cruz Mountains can take over a creek.

Its scientific name is Clematis vitalba, but most folks call it “old man’s beard” after its large, white flowers. Maybe you’ve seen this houseplant in your local nursery or a neighbor’s front yard, Native to parts of Europe and with no animals or insects that want to eat it in the state of California, clematis is an highly invasive plant here that can engulf an entire watershed.

Left unchecked, clematis wraps its tendrils around the base of nearby trees. Next, it climbs until it has secured as much sunlight as it can – often choking out and killing the trees and native ground plants. Then, with nothing to stop its advance, our forests are reduced to­­ big ugly mats of a gnarled, non-native weed.

The Resource Conservation District of Santa Cruz County was the first to identify the 30-acre patch of clematis in San Vicente Redwoods in 2011. That same year, POST and our conservation partners acquired the 8,532-acre property near Davenport. So, when we protected this land, we became its steward and owned the challenge of eradicating this seemingly unstoppable plant.


Why is clematis such a big problem?

Clematis can have devastating impacts on the local ecosystem. As it grows larger and takes over more of the forest floor, it creates a monocrop unsuitable for most native species. This is especially true for our native insects who rely on the diversity of our forest’s vegetation.

Clematis vitalba - Pian dei Grilli, Genova, Italy
Clematis vitalba

Some folks might think that fewer insects would be a good thing, but they are a critical link of the food chain. Insects feed the birds, fish and small mammals that in turn feed predators like bobcat and mountain lion. Suffice it to say, clematis strips the ecosystem of one of its foundational ingredients – bugs.

We’re also losing redwood and other native trees along San Vicente Creek, smothered by this invasive’s persistent sprawl. Fewer trees has allowed more light to enter and warm San Vicente Creek, putting added pressure on the creek’s endangered Coho salmon.

This is where the conservation community really drew the line. Yes, this work is about restoring the balance of the entire ecosystem, but we are especially concerned about saving these endangered fish.

How are we planning to fix this?

In 2016, POST and the Sempervirens Fund secured a $1.14 million grant from the California Department of Fish and Wildlife to eradicate clematis from San Vicente Redwoods. Over the next three years, we will be working with our partners and contractors to systematically remove this plant from our property.

It feels good to have gotten our hands dirty this summer. With help from the California Conservation Corps, our contractors at Go Native removed approximately 10,500 pounds of invasive plant material.

And we’re just getting started. Over the next three years, we will be testing various methods to remove this plant. We’ll carefully document our learnings so they can be applied in other parts of the country with this same problem.

We have a responsibility to San Vicente Redwoods and the bugs, birds, fish and trees that call it home – it’s what we signed on for when we protected this property. Today clematis is threatening the health of this landscape, but we’re confident we’ll triumph over this surprisingly aggressive houseplant.


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About Post

Peninsula Open Space Trust (POST) protects open space on the Peninsula and in the South Bay for the benefit of all. Since its founding in 1977, POST has been responsible for saving more than 87,000 acres as permanently protected land in San Mateo, Santa Clara and Santa Cruz counties. Learn more

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