Crews burn invasive weeds in Thurston County

Nearly 20 firefighters conducted a controlled burn Wednesday at a Thurston County prairie to kill invasive weeds and restore native plants.

The prescribed burn, a joint coordination between the Center for Natural Lands Management and Joint Base Lewis-McChord, was ignited at Mazama Meadows, a 134-acre Rochester flatland owned by CNLM.

This was the first controlled burn at Mazama. The plan was to blaze 34 acres. Weather, wind direction, humidity and smoke management — the brush is flanked by residential housing on both sides — control if that quota is met.

“It is kind of like a blank slate,” said CNLM restoration specialist Ben Harbaugh. “This is overwhelmingly invasive species, so the fire re-sets it so we can give the natives that competitive advantage. ... Also, a lot of native species are adapted to regrow after fires, whereas the invasive species are not adapted toward fire.”

The primary objective of the fire is to kill Scotch broom, an invasive weed from Europe that sabotages the habitats of insects, birds and gophers, CNLM Conservation Assistant Carola Tejeda said.

Scotch broom, nicknamed nitrogen fixer, pulls too much nitrogen into the soil, which kills surrounding plants.

“It invades the prairie and changes the soil chemistry so that nothing else will grow,” Tejeda said. “Each Scotch broom has up to 5,000 seeds, and those seeds can remain in the soil for 100 years.”

Mason McKinley, CNLM ecological fire program manager, said flames destroy Scotch broom and sustain minimal damage to deep-rooted native plants.

“If you can top-kill the Scotch broom, especially at this time of year, it actually will kill the whole plant,” McKinley said. “Usually plants don’t do that. We’re lucky that Scotch broom does. ... And a lot of the native plants have gone through their growth cycle, so they’re in decline right now anyway. By waiting until this time of year, we are reducing the impact on native plants.”

The burn will restore native flowers that will likely grow back in three to four months, Tejeda said.

Among those flowers are blue camas, a lily that feeds gophers and provides nectar to butterflies; the western buttercup, a yellow nectar and food plant for insects; and Pacific lupine, a spiked flower that caters to humming birds and other pollinators.

Wildfire prevention is another benefit of controlled burns. The high temperature Wednesday was 84 degrees, Tejeda said, which is heat that creates extremely dry vegetation in the field.

“These plants have no water, so it catches fire really easily,” Tejeda. “We are reducing the amount of dried plants that could burn without us here.”

If a wildfire were to ignite in a prairie, CNLM has taken measures to contain it. Around many prairies in Thurston County, there are perimeters made up of a combination of ditches, roads and rivers that prevent fire from spreading.

“Each prairie is divided into units,” Tejeda said. “And around each unit there is a fire break. So the fire will stop at that line.”

The Mazama Meadows is slated to become a pocket gopher mitigation site, McKinley said.

The mitigation site, or conservation bank, is an exchange between landowners and Mazama, McKinley said. If a person intends to develop property — build a house, neighborhood, business — and it is inhibited by pocket gophers, they have to barter with Thurston County.

The acreage of land a property owner destroys for development will be the amount they will be charged, or credited, to restore a piece of land in a different area — Mazama Meadows.

“Property owners would come to us and say ‘We need to buy three credits,’” McKinley said. “Then we use that money to keep Scotch broom out and further maintain this habitat.”

This story was originally published July 27, 2016 at 6:02 PM with the headline "Crews burn invasive weeds in Thurston County."