Weeding Out the Problem

An invasive bamboolike weed that can grow 4 inches a day has found a firm toehold along one Shasta County creek — with the help of an otherwise beneficial critter.

The "alarming" discovery was made during recent studies along Stillwater Creek east of Redding, where surveyors spotted beaver dams made with the invasive Arundo donax species, an aggressive Mediterranean plant that soars up to 30 feet tall.

Beaver normally snag branches from willow and other native species to build their structures.

Now they're favoring Arundo, which spreads quickly when stem or root segments wash downstream and land in moist soil.

But don't blame the beaver, said Valerie Shaffer, a biologist with the Western Shasta Resource Conservation District. Beaver are ecologically friendly, altering stream flow with their dams and improving habitat for fish.

"This is the one instance I have seen as a biologist where they (beaver) are proving to be a detriment," Shaffer said. "I'm hoping people won't see beavers as the bad guys here. The beaver are just doing what beaver do."

Whomever you blame, Arundo — commonly known as "Giant Reed" — is getting to be a real problem, Shaffer said.

It was introduced in Southern California by Spanish missionaries and used as roofing material in the 1800s. It's still used today to make reeds for musical instruments.

Later, it was touted as a way to stabilize stream banks, and was planted by ranchers and farmers around the state, spreading north in the past few decades.

Officials now believe Arundo causes more harm than good.

For starters, it's highly flammable and doesn't provide much food or habitat for insects or birds.

In a big storm, the roots can break loose, releasing silt into streams and harming fish. Stalks of the plant have lodged underneath bridges, building up pressure and wiping out small roadways.

What's more, the dense Arundo blocks sunlight to other plants, yet doesn't lend enough shade for coldwater-loving salmon and trout. It's also insatiably thirsty, guzzling about 80 percent more water than some native species.

"We don't need a plant that causes our water tables to drop and begins to crowd out" other plants, Shaffer said.

In areas with low flows, Arundo might span an entire stream, disrupting flows and causing the water to heat up. And because it's nonnative, there are no species here tailored to keep it in check.

Paul Kjos, Shasta County deputy agriculture commissioner, said the weed has also shown up on Clear and Churn creeks.

"It's getting more and more prevalent," he said.

As soon as next month, the nonprofit conservation district plans to hold a public meeting on the issue and prioritize which sites need attention. Then they hope to win grant money to wipe out the reeds.

It may not be easy.

Dave Du Bose, president of the Shasta chapter of the California Native Plant Society, said one rancher dug 14 feet deep and still couldn't snag all the roots.

There are 1,000 other nonnative weeds in California, and not enough money to eradicate all of them, Du Bose said.

When it comes to weeds, he added, it's important to act early.

"There's very few people doing anything about this," he said. "Some people are talking about it — I guess that's the first stage."

As for the beaver, they may be attracted to Arundo simply because it's convenient, Shaffer said.

"Here's this funny new plant that's suddenly in their habitat," she said. "It's right where the willow would be."

Images: (Top)  Valerie Shaffer, a biologist with the Western Shasta Resource Conservation District, stands in front of a massive Arundo donax along Stillwater Creek east of Redding. Officials fear the nonnative weed is forcing out other more beneficial plants. Its spread has been aided lately by the beaver, which is using Arundo to build dams along the creek.  (Lower) Arundo spreads easily. Sections of the plant that break off and flow downstream may be re-established if they land in moist soil. The bamboolike plant grows up to 4 inches a day and can reach a height of 30 feet.

Courtesy of Record Searchlight