Forestry experts say years of drought weakened the trees to a plague from the native bark beetle.
FRESNO, Calif. (KFSN) -- Millions of dead trees plague the Sierra National Forest as firefighters work to save those that are still living from the Creek Fire.
"There are estimates that right now there are over 1,000 tons per acre of dead and downed fuel," said Tyler Monroe with the U.S. Forest Service.
Experts say that 2 million tons of dead wood is what helped fuel the inferno, along with weather conditions and steep terrain.
"When fire hits that and consumes that, it is going to start quicker and when it burns it is going to burn hotter," said Seth Brown, CAL FIRE Battalion Chief.
Tree mortality has been an ongoing issue throughout the Fresno and Madera County mountains.
Forestry experts said years of drought weakened the trees to a plague from the native bark beetle.
"They find that weakness in the trees and they have the ability to attack and the trees defenses were weakened," said Adam Hernandez, Reedley College instructor.
Since those trees don't get enough water they can't produce sap which would push the insects out.
"The bark beetle was able to bore into the tree and once that started happening multiple times it can actually kill the tree," said Brown.
Agencies have worked together to clear out some of the dead wood on the federally-owned Sierra National Forrest.
Their areas of focus have been populated areas and main roads like Highway 168.
But it hasn't proven enough, as the Creek Fire continues to tear through the mountains.