Posted by: John | October 10, 2008

Not All Grass is Greener…

Drakes Estero and Abbotts Lagoon are visible from Mount Vision on a clear day.

On a clear day, Drakes Estero and Abbotts Lagoon can be seen from the top of Mount Vision. Image by John C. Cannon.

Dealing with the invasion of nonnative species is a central focus of many biologists at Point Reyes. Bullfrogs, mosquitofish and iceplant, to name a few, have wormed their way into ecosystems in the park, exploiting niches where they can beguile unacquainted potential predators and outcompete their native counterparts in the contest for resources.

And while many populations of these interlopers are well established, others are still revealing themselves during routine diversity and inventory studies undertaken by park scientists.

As these small populations crop up, says restoration biologist Ellen Hamingson, it’s important to nip the problem in the bud—quite literally in this case. To control invasive populations before they get out of hand, “we look for things we know are invasive, but are now low in abundance,” she says.

Native to Europe, sweet vernal grass was discovered near the peak of Mount Vision this summer. Image by Lindsay Herrera.

On a routine survey this past summer, biotechnician Melissa Potter discovered a smattering of sweet vernal grass, an invasive species from Europe, for the first time in the park on Mount Vision, northwest of the visitor center (view a video on the importance of vegetation mapping here). Though park scientists don’t shy away from large-scale projects—a multi-year project is currently underway involving heavy equipment and hundreds of volunteer, contractor and staff hours to root out prolific iceplant from nearly 200 acres of parkland surrounding the lighthouse—an early investment to remove this small, isolated population of sweet vernal grass could obviate the need for more drastic measures down the road when the incursion might become more serious.

So Hamingson and Potter organized a work trip to confirm the locations (by GPS) of the sweet vernal grass on Mount Vision and to remove as much as possible. As with many park projects, volunteers were a big part of the plan. But because this particular invasive species was only sparsely present among other types of native grass, they couldn’t just ask their helpers to slash through a bunch of vegetation without regard for what they were destroying.

Fortunately, the “weed warriors,” as they call themselves, who came to the slope of Mount Vision that day “weren’t your typical volunteers,” says Hamingson. Hailing from the eastern shores of San Francisco Bay, the women were members of the Friends of Five Creeks organization. In addition to looking out for water quality, greenspaces, and native species in “urbanized” East Bay through a host of hands-on volunteer projects, members of Friends of Five Creeks foray beyond their stomping grounds to take on problems in other areas.

Distinguishing sweet vernal from the myriad other grasses on Mount Vision required skill and experience, but should be easier in the spring. Image by Lindsay Herrera.

Their expertise in identifying pernicious nonnatives proved invaluable to Hamingson and Potter. The group spent the morning hours teasing out sweet vernal grass from the vegetation abutting Mount Vision Road, searching for the brown seed heads that are subtly darker than those of surrounding species in the early fall. They also removed massive clumps of purple velvet grass, another invasive nonnative. Populations of this species are so pervasive that it’s not actively managed in the park, Hamingson said, but removing it along with the sweet vernal would cause no harm.

Shortly after a lunch break, the team attacked one of the probable points of initial growth–a brushy area, just a few meters off the road where beds of the dark golden grass grew thick. Staging this initial removal was the first step in trying to keep sweet vernal grass under control at Point Reyes. Members of Friends of Five Creeks have pledged to return in the spring, when the seed heads are green and easier to identify, to take the next step in stamping out sweet vernal grass.

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Responses

  1. VERY INTERESTING! Love the pix. Wonderful how the right people showed up for the right job!


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