Crews working to protect giant redwoods at Armstrong Woods in Sonoma County

GUERNEVILLE, Calif. - Two weeks into the Walbridge Fire, historic redwoods remain at risk in Sonoma County. 

The Armstrong Woods State Reserve is located in a canyon north of Guerneville.

It is home to hundreds of ancient coast redwoods, many hundreds of feet tall.

"What's the value of a tree that's 1,800 years old? Priceless," said California State Parks Forestry manager Bill Maslach, taking KTVU on a tour of the closed park.

Armstrong Woods may not be as famous as Muir Woods National Monument in Marin County, but Armstrong attracts more than 1 million visitors every year.

A highlight is its namesake, Colonel Armstrong, a tree more than 300 feet tall.

But for now, firefighters are taking in the views, as they spray water on smoldering redwoods.

"It's our first time in the redwoods," said a firefighter from Southern California.

"First time, and it's beautiful!," added another.

At times, it has been a hectic firefight, as the blaze that began with a lightning strike at a higher elevation crept down to the grove as days passed. 

"There were people monitoring, staying out here all night, looking for trouble situations," said Maslach.

"Many people say redwoods are used to fire, they evolved with it, they like it, but actually they don't like infrequent fire."

And it hasn't burned in the area in 100 years or more, so material has built up around the base of the trees.

Redwood needles, known as duff, has collected along with fallen logs and limbs.

When the accumulation burns, it bakes the redwood's shallow roots.

Bark, which provides moisture and a protective shield, can also be damaged. 

"If there's no bark, then fire gets on the wood and has direct contact, which we don't want," explained Maslach.

Friday, fire crews were monitoring prescribed burns of the excess vegetation, away from the tree trunks.

Already, the heat has caused some redwoods to burn and fall.

"We've been hearing some giant trees come crashing down at alll hours, but the park came through pretty well I think," Lathrop Leonard, a forest ecologist for the California State Parks. 

That's reassuring for residents of Russian River communities, who were alarmed when flames started licking along the forest floor.

For ecologists, though, it's not altogether bad. 

"I think we got lucky this time but it's a reminder we have to get fire in here on a regular basis so we don't have this build-up of fuels again," said Leonard. 

Fire crews will remain in the park, dispersing embers and snuffing out hot spots as the damage is assessed.

Many firefighters from outside the area, have never had such scenic duty before.

"It's totally new to me and they are beautiful trees," said fire engineer Jim Blevin, manning an engine from San Diego County.

"But I'd like to come back when it's not so smoky!"

Another notable tree is Parson Jones, towering more than 300 feet, 1,300 years old, and almost 14 feet in diameter.

"This park has been loved by the community and by people who have visited it," said Maslach.

Armstrong Woods is closed for safety, but in time there will be opportunities to volunteer and support restoration.

A non-profit group, Stewards of the Coast and Redwoods, works cooperatively with State Parks to promote and protect Armstrong and the adjacent Austin Creek Recreation Area.