Fire Essential to Giant Sequoias' Survival, Also Potential Threat

Published 08/21 2014 06:38PM

Updated 08/21 2014 07:31PM

When wildfires burn out of control, they sometimes threaten to get too close to some of our natural treasures in national parks.

Most recently, the El Portal fire three weeks ago threatened to char a cluster of giant sequoias in the Merced Grove of Yosemite National Park. Fire crews had to take a defensive approach and build lines to intercept the progress of the fire, according to Taro Pusina, deputy fire chief of prescribed fires and fuels at Yosemite National Park.

The sequoia trees are some of the largest living things on earth.

Throughout the year, fire crews take preventive measures to protect them. But there's a balance fire crews keep between preventing fire from being destructive and using fire as a benefit to the sequoias.

The giant sequoia trees only grow on the western slope of the Sierra Nevada mountains.

People come from all over the world to see them, some of which are more than 200 feet tall and almost 2,000 years old.

"[They] really capture the imagination of the people--just the beauty, the size, the durability, their ability to withstand fire, to withstand generations," says Scott Gediman, park ranger and spokesman for Yosemite National Park.

The trunks of many of the sequoias are scarred by fire.

While everyone knows fire is destructive, what fire crews also know is that it can actually help preserve a natural ecosystem.

"In fact, these giant sequoias absolutely have to have fire in order to reproduce. Without fire, they're going to die," Pusina says.

The giant sequoia cones carry thousands of seeds, but they need the excessive heat of a fire to be able to open up.

Once the seeds are released, they need to fall on bare mineral soil.

This is, again, where fire plays a role. A prescribed, controlled burn will get rid of forest debris to make room for new growth.

"If they fall on a bunch of pine needles and sticks and branches, they won't be able to get established. They need that bare soil," Pusina says.

The prescribed fires also help get rid of brush and undergrowth that fuel massive and uncontrolled wildfires.

But in this drought year, Pusina says, they are not doing any prescribed burns in the lower elevations. It presents a challenge.

In Yosemite National Park, there are three groves of giant sequoias. All three have been threatened as recently as this week, with the Junction fire causing concern.

"We had a fire in Oakhurst, which had the potential to come up the Luis Creek drainage and physically impact the Mariposa giant sequoia grove," Pusina says.

He adds that fire crews prevented the Junction fire from approaching the Mariposa Grove.

Although these giant sequoias are pretty fire resistant, these forest jewels are not something crews want to put to the test in a massive wildfire.

"You don't want these big 150, 200 foot tall trees completely going up in flames. You don't want that kind of fire running at these trees," Pusina says.

Besides using controlled burns, fire crews are able to clear forest debris manually and thin out the forest using chainsaws and other equipment.

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