Whether Gov. Arnold Schwarzenegger is making a serious proposal or indulging in a bit of grandstanding, the temporary closure of at least some state parks isn't unthinkable in a budget year this dire. What the number crunchers must realize, though, is that "closed" isn't the same as "no cost." The state must patrol and minimally maintain the parks with or without visitors or it almost surely will incur worse expense, not just long term but in the immediate future.
Closing parks doesn't mean that people won't use them. It means that law-abiding people won't use them. Among those who will: meth lab operators, marijuana farmers, the homeless, taggers, poachers, rogue mountain bikers and off-roaders, as well as just plain campers who think the rules don't apply to their personal visits. Wildfire danger would increase from illegal, unsupervised campfires, sparks from off-road vehicles and drug operations. The cost of a single catastrophic fire could wipe out most of the savings from closing parks. Crime could turn the parks into expensive public nuisances.
That's on top of the long-term expense caused by erosion problems from illegally cut trails, vandalism, deterioration of park buildings and the need to bring back overgrown trails once the parks reopen.