California black oak comprises a total volume of 29% of California's hardwood timber resources, and is the major hardwood sawn into lumber there. The total estimated area of species occurrence is 361,800 ha (3,618 km² or 894,000 acres); 239,200 ha (2,392 km² or 591,000 acres) of timberland and 122,600 ha (1,226 km² or 303,000 acres) of woodland. Of this land 60% is privately owned, 31% is in National Forests, and 9% is on other public lands. It has greatly decreased from its historic abundance. This is due to a number of factors, including drought, disease, animal foraging, logging practices, fire suppression, and a variety of other human impacts. Cutting green trees for fuelwood has contributed to the decline of this species, and illegal harvesting of green trees from public lands is a continuing problem.