Weed whackers: Crew works to prevent spread of invasive grass

Posted: Friday, July 23, 2010

The Slikok Creek reed canary grass abatement continued this year by the Kenai Watershead Forum.

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Photo By M. Scott Moon
Photo By M. Scott Moon
Tyler Parrish, Matt Webster, Sean Jones and Anthony Oder pull a canoe full of reed canary grass down Slikok Creek earlier this week. The team has been working to clear the creek of the invasive species.

Watershed forum Invasive Species Specialist Michelle Martin had walked through the shallow creek last year to assess the amount of grass present. Martin said that the canary grass was still there, but previously mitigated areas had shrunk or disappeared.

"It's gone from some areas and a few stems in others," she said.

Tyler Parrish, who works with Martin, said that the crew spent most of their time digging out the grass in and around Slikok Creek. Crews load the removed vegetation onto canoes and bring it to docks along the water or places where the stream intersects with roadways.

Martin said that Slikok Creek has minor infestations; the North Fork, a tributary of the Anchor River, has "extensive" amounts of reed canary grass, as does Bishop Creek in Nikiski.

"Bishop Creek is the place we're most concerned about because it's not as accessible," she said.

The forum has also done work along Beaver Creek and Bing's Landing Campground.

Reed canary grass is an invasive plant species that poses a threat to salmon-bearing streams. The grass spreads not only through seed, like native bluejoint grass, but by rhizomes which creep through the ground and can sprout in gravel beds.

Gino Granziano of the Alaska Department of Natural Resources Division of Agriculture said that the canary grass increases sedimentation within the gravel where salmon lay their eggs. Granziano said that the sedimentation decreases the amount of oxygen within the gravel, clogging the spawning ground.

The rhizomes can also spread beneath the creek and sprout in the middle of the waterway. Martin said that the grass slows smaller rivers, which adds difficulty for juvenile salmon traveling upstream.

Graziano said that the grass overtakes areas where trees normally grow, which limits the amount of "woody debris" in streams. The dead trees' decomposition process attracts insects and tiny crustaceans that make up a salmon's traditional prey.

Martin said that she hasn't seen many signs of salmon blockage, but considers reed canary grass enough of a threat that there should be an effort to at least contain the growth.

According to Granziano, farmers brought the reed canary to the Peninsula because it can be used as a feed for livestock. The densely growing plant can prevent soil erosion, which may have brought it near Alaska's streams.

Digging out roots only mitigates smaller patches, Martin said. The forum has considered applying for permits to spray herbicide on grass along the streams, but Martin said the public doesn't usually support the use of chemicals near waterways.

"Dealing with something as potentially damaging as the grass, I'm in favor of herbicide," she said. "I wouldn't expect to get permission though."

The forum also staples tarps over larger canary grass patches in their abatement efforts. Workers lay sandbags on the corners of the tarp to hold it down as well. The roadside-grade fabric deprives canary grass of sunlight and eventually kills the species, along with whatever other plants are underneath.

Parrish said that he had laid down four tarps since he started abating this summer. Another worker, Anthony Oder, said that he had repaired tarp tears by draping more fabric over the holes and dropping a sandbag on top to keep it in place.

Martin said that the forum will begin harvesting native blue joint grass soon for a re-vegetation project next summer.

Tony Cella can be reached at tony.cella@peninsulaclarion.com.

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