You're thinking of forests in California and the rest of the Southwest Many (most?) PNW forests sit on very deep peatlands. When they burn, it's a catastrophic

You're thinking of forests in California and the rest of the Southwest Many (most?) PNW forests sit on very deep peatlands. When they burn, it's a catastrophic release of captured carbon like the fires Canada has been experiencing over the last few years. Once those fires start, it becomes a vicious cycle of fire drying out deeper peat which burns the next fire season, sometimes smoldering underground for years before burning out.