Many of those fires were started by Native Americans as management fires, as part of their agriculture. What fire does is help control insects and fungi, so the acorn and pine nut harvests are better and more available as food. Burning also helped produce materials for their manufacturing. Escaped fires and those caused by lightning also swept regularly through the ancient forests. And not only the forests.
Some people believe the whole northern Sacramento Valley burned off every year.
Native grasses were just as dependent on fire as the ponderosa pine and black oak forests. Professor Hodgson is taking this message to communities throughout California, particularly those in areas regularly threatened by wildfire. As part of a team funded by the CSU, Chico Foundation Research Center, Hodgson and his colleagues are beginning to transform the public attitude towards fire and, just as significantly, to transform communities themselves from potential tinderboxes into towns a fire can burn through with relative safety. As radical as this sounds, Hodgson insisted that it makes sense. Then, in the 1850s, we came in and began logging, which changed the structure of the forest.