The Black Hills region has been described as an island of trees in a sea of grass. The forest is unique due to its location and elevation and is home to at least 12 major species of trees. The most common trees, ponderosa pine, Black Hills spruce, quaking aspen, paper birch, bur oak and green ash are covered here.
Ponderosa pine: western yellow pine, yellowbark pine, bull pine, blackjack pine
Botanical description of ponderosa pine: Needles in fascicles of 2 or 3, 5” to 11” long dark gray-green to yellow-green. Cone oblong ovoid, light reddish brown, 3” to 6” long with a small prickle at the end of each cone scale
Ponderosa pine is the most abundant pine in our region with almost one million acres of ponderosa pine in the Black Hills and scattered forests to the north, south and east. The tree can be found up in the Slim Buttes country and south into the Pine Ridge of Nebraska and then east to Tripp County, S.D., the farthest east it occurs naturally in the United States. The tree is also native across eastern Wyoming. Ponderosa pine is the second most important timber tree in the nation, just behind Douglas-fir and is the timber species in the Black Hills. Sawtimber, includes pines 9 inches in diameter (at 4.5 feet above the ground) or greater, is the source for lumber production in the Black Hills and supports a major industry.
The common names yellowbark, and bull pine refer to the majestic large trees in the Black Hills that have the bark broken up into large yellowish brown scaly plates and are deeply furrowed. The younger trees bark has brown black scales and these trees are called blackjack pine. The oldest ponderosa pine in the Black Hills is about 720 years old (in 2011) and the average ponderosa pine can live for several hundred years. The oldest ponderosa pine in the Black Hills, the Reno Gulch pine, stands on a rocky ridge at about 5,800 feet of elevation. Despite the age, the tree is not that large, about 45 feet tall and 20 inches in diameter. One of the largest pines in the Black Hills was the Giant of Herbert Draw, though only 400 years old, it was close to 100 feet tall but fell victim to mountain pine beetles in 1972 and was harvested.
Ponderosa pine is intermediate shade tolerant meaning it can regenerate and establish under partial shade though there will be improved performance growing in full sunlight. It does not self-thin so thick “dog-hair” stands of sapling size pines are a common sight in the Black Hills. Thinning a ponderosa pine stand at various times throughout the rotation is essential for promoting good growth and form.
Ponderosa pine in addition to being a valuable timber species is also important habitat for wildlife. Elk, white-tail deer and mule deer all depend on pine stands for thermal and hiding cover. However too dense of pine stands can reduce forb production on the ground and limit food sources for these animals. Ponderosa pine stands are also home to more than 30 bird species.
Ponderosa pines are resistant to light surface fires due to their thick bark but when stands are allowed to become dense, ponderosa pine is vulnerable to wildfires that engulf their canopies. There are two major pest problems for ponderosa pine, the mountain pine beetle and the pine engraver beetle (Ips pini). Both these insects injure trees by burrowing great networks of galleries beneath the bark. The mountain pine beetle is a tree-killer, often mass attacking a tree and killing it within a year of the initial attack. The beetle prefers crowded forests so is less common in open, park-like stands. An epidemic of mountain pine beetle began in the late 1990s and at the time of this writing (2011) has killed more than 3 million trees. The pine engraver beetle typically attacks stressed trees, sometimes killing only branches or tops. This insect can be a problem in some urban areas adjacent to forests and has been found in shelterbelts as far from the Black Hills as Shadehill Recreational Area near Lemmon, S.D.
The tree is also susceptible to two diseases, diploida tip blight that can leave the tips of the shoots stunted and dothistroma needle blight that can result in the loss of foliage. The two diseases are common in ornamental and windbreak planting s of this species.
While ponderosa pine is the most common pine to the Black Hills, there are also small stands of lodgepole pine (Pinus contorta) and limber pine (Pinus flexilis). Lodgepole pine is native to the Black Hills, although found in only a few scattered locations. It does, however, it dominate the western forests of North America forming extensive stands in Yellowstone National Park among many other western forests. Limber pine exists in small groups in the Cathedral Spires although these trees are showing infection by the white pine blister rust (Cronartium ribicola) a deadly disease of 5-needled pines. There are also small scattered stands of limber pine in southwestern North Dakota.