Westend, above, is correct. Someone should point out that carrying firewood is allowed, at least in the state member CAJW above from California has noted his link.
Don't Move Firewood, run by The Nature Conservancy, is a lobbying group and not the government.
California Firewood Task ForceAre CA Government
recommendations regarding moving firewood within California, which is LEGAL. Each state has its own restrictions. While The Nature Conservancy has some positive attributes in its work, they're not legislators and their recommendations are not the law. Californians are welcome to cut, buy or haul whoever's firewood they want within the state. It's probably one of the last things where we have a free say in personal choice.