President Donald Trump on Wednesday threatened to withhold billions of dollars of federal funding if California does not clean up its forests to reduce the risk of wildfires, a year after some of the worst blazes in the state’s history.

Some of the wildfires that engulfed California a year ago were caused by downed power lines and damaged electrical equipment.

Traditional indigenous burning practices are protecting plant biodiversity in Australia's Gibson Desert, according to new research. The study analyzed how environments dominated by flammable spinifex grasses and fire-sensitive desert myrtle shrubs reacted to wildfires, and to the low-intensity burning practices of the Pintupi people.

Islands of greenery, called refugia, survive even the worst fires, sheltering species and renewing charred landscapes.