US Wildfires: World's largest tree wrapped in protective blanket

Firefighters are attempting to save the world's largest tree from wildfires in the US by wrapping it in aluminium foil and starting their own fires to burn away flammable material.

The famous grove of gigantic old-growth sequoias is under threat from wildfires burning in California’s rugged Sierra Nevada.

The world's largest tree by volume, The General Sherman, in Sequoia National Park’s Giant Forest, was wrapped in protection against the possibility of intense flames.

Several key buildings and other sequoias were also wrapped.

The aluminium wrapping can withstand intensive heat for short periods.

Officials say they have been using the material for several years throughout the US West to protect sensitive structures from flames.

The Colony Fire, one of two burning in Sequoia National Park, was expected to reach the Giant Forest, a grove of 2,000 sequoias, at some point within days, fire officials said.

It comes after a wildfire killed thousands of sequoias, some as tall as high-rises and thousands of years old, in the region last year.

The General Sherman Tree is the largest in the world by volume, at 1,487 cubic metres and towers above at a mighty 84 metres in height, according to the National Park Service.

Firefighters have resorted to starting their own fires in the region in order to burn away flammable vegetation in a controlled manner so it can't be used to fuel out of control wildfires.

The tactic comes with considerable risks if conditions change but it is routinely used to protect communities, homes or valuable resources now under threat from fires.

Firefighters on Thursday were conducting burnout operations in the Giant Forest at almost a micro level, moving from tree to tree to remove any flammable vegetation.

By removing the vegetation, firefighters hope the wildfires will either be steered away from the ancient trees or have weakened to such an extent they won't cause damage to them.

Giant sequoias are adapted to fire, which can help them thrive by releasing seeds from their cones and creating clearings that allow young sequoias to grow, but the extraordinary intensity of the recent wildfires can overwhelm them.

A historic drought and heatwaves tied to climate change have made wildfires harder to fight in the American West.

Scientists say climate change has made the region much warmer and drier in the past 30 years and will continue to make weather more extreme and wildfires more frequent and destructive.

The fires forced the evacuation of the park this week, and parts of the town of Three Rivers outside the main entrance remained evacuated.

To the south, a fire on the Tule River Indian Reservation and in Giant Sequoia National Monument grew significantly overnight to more than 6 square miles (15 square kilometres), and crews had no containment of it, a Sequoia National Forest statement said.

The wildfires are among the latest in a long summer of blazes that have scorched nearly 3,550 square miles in California that have destroyed hundreds of homes.