Whitney Preserve
Whitney Preserve The Nature Conservancy’s Whitney Preserve in western South Dakota. © Mike Deal

Stories in South Dakota

South Dakota Nature Notes

Despite the heat, it's a great time to visit the Black Hills forest and South Dakota's prairies.

August can be a hot month. But even at this time of year, plants that thrive in cooler settings are able to survive on the north-facing slopes of higher elevations in the Black Hills. Plants from a variety of environments grow in the Black Hills, creating a unique botanical crossroads. In the Black Hills, there are eastern hardwoods, western coniferous forests, and Great Plains grasslands as well as plants from northern boreal forests. Go to the right place here and even on a hot summer day in South Dakota, you can find plants that also grow in Canada, New England or the upper Great Lakes region.

These cooler climate plants form a disjunct forest—they are not contiguous with the boreal forests further north. They are relics from colder times thousands of years ago in the Pleistocene when boreal forests extended south, and they have survived in this “island in the plains” that the higher elevations of the Black Hills provide. White spruce, also called Black Hills spruce, form dense pockets of this forest in the northern regions of the Black Hills. Lichen called “reindeer moss” or “old man’s beard” often hangs from the lower branches of these trees; its long, stringy bluish-green growth can make the forest seem lush. Beneath the trees grow ferns, sedges and even club mosses (in a few rare locations), also called “ground pine” or “princess pine.” A good place to see this northern forest is in the Botanical Area near the Black Fox Campground, approximately eight miles west of Rochford on FR 231. 

Most of the forest in the Black Hills is made up of ponderosa pine, a valuable timber tree that unlike white spruce is tolerant of hot, dry growing conditions. Stands of ponderosa pine cover foothills and ridges in the Black Hills, and in August some of those trees may be attacked by mountain pine beetles. These tiny insects bore into a pine and create galleries of tunnels immediately beneath the tree’s bark. The galleries soon become nurseries for beetle larvae that expand the tunnels as they consume wood and grow. The larvae overwinter in the galleries and emerge as adults the following summer, sometimes as swarms of insects that can overwhelm and kill trees. Pines harboring beetles may not be obvious—look for the amber plugs of resin secreted by a tree to seal the bore holes of beetles. That defense mechanism may save a tree when beetles aren’t numerous, but in years when beetles are abundant many pines succumb, killed by the girdling effect of the tunnels and by fungi that often accompany the beetles. Beetle outbreaks occur about every eight to ten years and an outbreak may last five to thirteen years. During that time, swaths of dead pines, their needles turned red, reveal the impact of a mountain pine beetle infestation.

August is also an excellent time to explore South Dakota’s prairies. Late-summer grassland flowering plants include many kinds of composites, often called asters or daisies. Not all look like the familiar daisy—blazing star is a composite with tiny flowers that form a tall, dense purple spike. An impressive composite that blooms in August is the Maximilian sunflower that can grow eight feet tall with flower heads up to four inches wide. Tallgrass prairies such as the Aurora Prairie are good destinations to see these and other wildflowers in August. The Conservancy’s Samuel H. Ordway Jr. Memorial Preserve conserves both tallgrass and short grass prairie and visitors there in August can also observe waterfowl and shorebirds in its numerous pothole wetlands.