There are wars most people don’t notice right here in Juneau.
There’s a war between fireweed and reed canary grass out at Brotherhood Bridge. There’s one between thimbleberry patches and Bohemian knotweed out at Auke Recreation Area. Basically, the battles — there are thousands out there — are between Southeast Alaska’s native plants and the 99 invasive species that invade their territory just here in Juneau.
If you’re wondering why that matters, the answer’s simple: everything affects everything else. When reed canary grass takes over the lupine, cow parsnip and other species, that means caterpillars and other invertebrates don’t have the habitat they’re used to, and it means coho salmon fry may not be able to get the food they need (food that lives on land is 50 percent of their diet).
This past week, invasive species experts from around and outside Alaska converged in Juneau for the University of Alaska Fairbanks’ Cooperative Extension Service’s 2015 Alaska Invasive Species Workshop. Monday, local U.S. Fish and Wildlife Service biologist John Hudson, the keynote speaker, talked at the Mendenhall Valley Public Library about “Juneau’s Green Invasion.”
Juneau’s invasive plants are clearly following people’s development of natural areas, Hudson said.
“Invasive plants tend to follow humans, because we’re creating these great disturbed habitats,” he said.
Many are growing, say, in Lemon Creek, next to gravel pits, or in commercial areas.
“The worry is that they’ll jump ship and jump into natural ecosystems,” Hudson said. “They’re doing a pretty good job of following us around.”
One Southeast natural feature seems to be doing a pretty good job of resisting invasive species: dense spruce and hemlock forests.
Meadows, wetlands, beach fringe habitat, riparian zones and stream banks, however, are another story.
Hudson said there are 99 non-native plants that have been found in Juneau at one time or another, and narrows that to 18 which pose the biggest threat. Some, like cheat grass and bird vetch, are highly invasive, but only in some areas. The Southeast Soil and Water Conservation District is a big component of eradication efforts, recently conducting the first comprehensive survey of the Mendenhall Wetlands State Game Refuge; they’re funded and helped by the U.S. Fish and Wildlife service, another big participant in eradication efforts, and the U.S. Forest Service. Some other partners help as well, signed on under the umbrella of the Juneau Cooperative Weed Management Area. The partners have narrowed areas down to a priority approach, particularly in watersheds like Peterson Creek, Auke Lake and Montana Creek.
“We know we can’t control every invasive plant in everyone’s backyard here in Juneau,” Hudson said.
Montana Creek is a striking example: They’ve been working to eradicate 560 infestations, from 18 species of invasive plant, across seven acres, Hudson said.
It’s also a place they’ve had some success — he’s pretty sure they’ve gotten rid of three out of the four most threatening species.
Another place is the Mendenhall Wetlands State Game Refuge, where, he pointed out, 230 different bird species have been seen at one time or another.
The big worry there is reed canary grass, which could compete with native sedges. Fortunately, most of the 129 infestations they’ve counted are along Egan drive.
Along the Mendenhall River, there’s a six-acre infestation, he said, comparing it to a cancer. Now, he said, it’s beginning to encroach on the fireweed visible from Brotherhood Bridge.
“There are these sleeper cells scattered throughout the wetlands in different places, and that really worries me,” he said.
Bohemian knotweed is another of the most threatening plants. A whole new plant can take root and grow from a tiny piece. Hudson said he’s pretty sure it’s taken root out the road, for example, when people trying to eradicate it from their personal properties or other places dump it.
“It just takes over,” he said. “It’s having significant impacts.”
The only garlic mustard infestation in the state is in Juneau, said Southeast Soil and Water Conservation District Regional Invasive Plant Coordinator Brian Maupin in a later presentation. It most likely originated in someone’s garden downtown, where it was first detected. It can take over some areas and is allelopathic — it releases chemicals that poison other plants. In an example of how long it can take to get rid of something that starts so small, in 2003, people involved in eradication efforts removed 600 pounds of the plants. Other years, they’ve pulled up to 150.
“We’re twelve years into this,” Maupin said. “It’s very difficult to find these plants. They hide in little nooks and crannies.”
The population of garlic mustard is 10 percent of what it once was, but Maupin doesn’t see it being eradicated anytime soon.
“We keep finding them, every single year,” he said. “This plant is a real threat.”
The news isn’t all bad, though. Hudson and Maupin are optimistic about eradicating knotweed. For all species, those working on invasive plants in town have been able to document invasive infestations well, and they’ve been able to prioritize.
The bad? It does take a long time to tell if an effort is working, and it can take a long time, Hudson said, to get permission to use herbicide, a significant part of some eradication efforts.
Some plants’ seeds can last 100 years, so eradication also isn’t the end of the story. People need to be on the lookout, Hudson said.
Genelle Winter, Invasive Species Program Director in Metlakatla Indian Community, spoke at the conference about efforts on Annette Island, where invasive species are edging out traditional subsistence plants. Some salmonberry, thimbleberry and huckleberry patches are now mostly knotweed, she said.
They found more than 1,000 tansy ragwort plants in one man’s yard alone. Kids assisting in the effort have collected 300 40-pound bags of knotweed. And that’s a miniature version of something she said needs to happen more widely across Southeast Alaska — collaboration. Southeast’s communities should focus not only on preventing invasive species from entering a community, but also on preventing them from spreading to others, she said.
• Contact Juneau Empire outdoors writer Mary Catharine Martin at maryc.martin@juneauempire.com.
Orange hawkweed and reed canary grass, both of which are highly invasive and widespread in Juneau, grow along Egan Highway.
