There are some plants or animals that would really be missed if they were removed from their communities. We call these “keystone” species because, like the keystone at the top of a stone arch, they allow many other parts of the community to remain in balance. Sagebrush, the scrubby bush found across the arid American West, is one such living thing. Throughout the Columbia Basin, where the Hanford Reach National Monument is located, Big Sagebrush (Artemesia tridentata) is the dominant species of sagebrush. Growing up to nine feet tall and living over a century, its spreading, twisted branches grow slowly through the seasons.
Here in the shrub-steppe, average annual precipitation is between five and ten inches, not enough to support trees, so shrubs like sagebrush, bitterbrush, and rabbitbrush fill that role in the community. Songbirds nest in their woody branches, and ground-dwelling birds such as greater sage grouse nest and take cover below them. Though a few of these shrubs retain their leaves through the winter, providing forage for herbivores such as mule deer, elk, and jackrabbits, Washington’s nickname “The Evergreen State” doesn’t properly match the foliage in this arid ecosystem. Spring brings a flush of green with new growth, but through summer, autumn, and winter the dominant colors are brown and pale, grayish-green. Light colors reflect the sunlight to reduce moisture loss, and you’ll see many plants utilize this adaptation, along with small leaf size and a fuzzy leaf surface. Despite its pungent smell, sagebrush leaves are an important food for sage grouse and endangered pygmy rabbits, especially through the winter. The shade of large sagebrush provides protection for grasses and flowering plants from the wind and sun. Hundreds of species have significant connections to sagebrush, and some are sagebrush-obligate, requiring this plant in their habitat.
Protecting lands such as the Hanford Reach National Monument is the first step to preserving this important shrub and the other living things that depend on it. Controlling invasive species is the ongoing work that will maintain the balance this keystone supports.