The thick-ridged, rugged gray-brown bark of the chestnut oak tree is covered with large vertical grooves and stands out distinctively in any mixed hardwood forest. The chestnut oak’s bark, as well as its often-crooked stature, distinguishes it from all other Pennsylvania oaks, especially in winter.
Chestnut oak (Quercus montana) favors acidic soils on dry slopes and ridge tops. It is more abundant in the southern half of the state than in the north but it is still common up north. It is one of two or three dominant tree species on our drier ridges.
During the warmer half of the year, chestnut oak can be recognized by its foliage. Its simple, alternately arranged leaves are 4 to 8 inches long and usually more than twice as long as they are wide. The leaves are lighter below, and the leaf margins are lined with rounded teeth. The leaves somewhat resemble those of the American chestnut, which is how the tree got its common name.
Swamp white oak, chinkapin oak and swamp chestnut oak have similar leaves, but not the thick grooved bark.
Chestnut oaks are slow-growing, even for an oak, and they are somewhat shade-tolerant. The tree is also relatively resistant to fire and heat damage. Some believe that this characteristic led to its survival during fires set by Native Americans, early settlers and those who followed the logging and charcoal-making booms in the late 1800s and early 1900s. Fire tolerance and the elimination of its major forest competitor, the American chestnut, due to a fungus disease, helps to explain chestnut oak’s abundance today.
Chestnut oak’s thick bark also protects it during controlled burns conducted by the Pennsylvania Game Commission. Only the hottest fires will damage the trees.
Chestnut oak is a member of the white oak group, whose acorns mature in one summer and are said to be “sweeter” than those of the red oak group because they have less tannin. Chestnut oak’s acorns are about the same oblong shape as those of white oak, but they can be twice as large.
Many animals — such as whitetail deer, black bears, squirrels and wild turkeys — relish the acorns of chestnut oak. Acorns are neatly wrapped packages of carbohydrates, protein and fat — perfect to fatten animals for the rigors of winter. White and chestnut oak acorns are usually consumed by animals before those of red or black oak.
Chestnut oak twigs are browsed by deer during the winter. The tree’s leaves are favored by the spongy moth and a host of other insects. Oaks attract a greater variety of insects than any other Pennsylvania trees. Migrating warblers feast on many of these oak-loving insects.
The wood of chestnut oak is hard and very heavy. Only a fool attempts to pound a nail into a dry chestnut oak board. This fact has earned the tree its other common name — rock oak. Each oak log is a densely packed bundle of energy-rich cellulose and lignin that makes it an excellent fuel wood. In fact, the rock oak has the heaviest dry weight of any Pennsylvania oak. That property translates to a high heat value.
Chestnut oak lumber has a relatively high resistance to decay and has many of the same properties of its close relative, white oak. Because of this, it is also used for flooring, railroad ties and rough construction. However, the tree’s propensity for crookedness lowers its lumber value.
Take a winter walk on just about any Centre County ridgetop and you will easily recognize chestnut oak by its bark. Also recognize this tree for its wildlife, lumber and firewood values. It may not be as stately as some other Pennsylvania trees, but it is an important part of the forest just the same.
