News article from Nature. Many foresters knew this, but research backs us up.
Indigenous knowledge reveals history of fire-prone California forest
A collaboration between scientists and Native American tribes finds tree density in parts of the Klamath Mountains is at a record high, and at risk of serious wildfires
“Combining multiple lines of evidence, Knight and her team show that the tree density in this region of Klamath Mountains started to increase as the area was colonized, partly because the European settlers prevented Indigenous peoples from practising cultural burning. In the twentieth century, total fire suppression became a standard management practice, and fires of any kind were extinguished or prevented — although controlled burns are currently used in forest management. The team reports that in some areas, the tree density is higher than it has been for thousands of years, owing in part to fire suppression.”
This is based on a PNAS paper here: