Yosemite National Park fire: Californian blaze threatens famous sequoia trees

Fires are edging close to Mariposa Grove, home to 500 giant trees

A firefighter protects a sequoia tree, as the Washburn fire burns in Yosemite National Park, California, US. AP

Smoke rises from the Washburn fire near the lower portion of Mariposa Grove in Yosemite National Park. AP

Flames from the Washburn fire near Mariposa Grove. AFP

A firefighter near Mariposa Grove as the Washburn fire rages. AP

A cloud of smoke rises from the fire in Yosemite National Park. AP

Helicopters drop water on the Washburn fire. AP

Visitors view the Yosemite landscape through a haze from the Washburn fire. Reuters

Trees are silhouetted by a wall of flames, as the Washburn fire rages in Yosemite National Park. AP

Wildfires are once again sweeping the Californian landscape and are threatening to engulf the ancient sequoia trees in Yosemite National Park.

The Washburn fire that started last Thursday has doubled in size over the past 24 hours, and is now burning across an estimated 645 hectares of terrain.

The official Yosemite website warns visitors of several alerts and road closures, and to expect smoky air and hazy conditions. Firefighters have so far evacuated campers and residents of the Wawona community from around Mariposa Grove, which is also the permanent home of 500 giant sequoia trees.

Slow-growing giant sequoias can reach more than 80 metres in height, making them some of the largest-known trees on the planet. The second-largest specimen in Mariposa Grove is called Grizzly Giant. It stands 63 metres high and is 7.8 metres around the base. Thought to be more than 3,000 years old, it highlights the remarkable longevity of the species, putting sequoias among the oldest living things on Earth.

To help protect the trees, the Yosemite fire and aviation management department has positioned sprinklers around the grove to increase humidity, and has removed all potential fuels. This is in a bid to prevent a repeat of the fires of 2021, that destroyed thousands of ancient sequoias, where an estimated 19 per cent of the world's 75,000 sequoias were destroyed.

These vast redwoods were once found all along the Pacific coast of North America, but now survive only in isolated pockets in California.

As well as being home to these ancient trees, the Mariposa Grove is also famous for being the first natural area to be protected for “public use, resort, and recreation” by then US president Abraham Lincoln in 1864.

The fires ranging across Yosemite are in contrast to the recent heavy rains experienced in the Yellowstone National Park, which caused widespread flooding and landslides that cut off large sections of the park.