The Nature Conservancy in Idaho - Biological Soil Crust

Karen Colson began working with The Nature Conservancy as a sagebrush ecologist in summer 2007. Her duties include the development of tools like the Landscape Toolbox, which offers a means to achieve practical, on-the-ground sagebrush conservation by integrating existing (but currently unconnected) methods with new, innovative approaches to assess analyze, conserve and monitor sagebrush ecosystems at a variety of scales. Colson previously worked for the Bureau of Land Management, and is the president of the Pahove Chapter of the Idaho Native Plant Society.

Learn more about the Landscape Toolbox and how if offers hopeful solutions for range management issues, with this downloadable fact sheet.

Conservationists often choose to decorate their offices and cubicles with a few familiar images: bugling elk, native trout, large predators, stunning landscapes.

Karen Colson has a poster of biological soil crust.

Don’t worry if you aren’t quite sure what biological soil crust is. You can even be forgiven if it brings to mind something like bread mold. Colson knows soil crust is relatively unknown, and largely unappreciated. It also happens to be an integral component of sagebrush habitat (and many other habitats worldwide).

Colson, the new sagebrush ecologist for The Nature Conservancy, is focused on developing tools to maintain and restore sagebrush habitats in Idaho. Biological soil crust is a critical component of that—and it’s disappearing fast.

Biological Soil Crust: Holding It All Together

The soil of healthy sagebrush habitat is not barren, as some imagine, but rather covered with a rich biological crust. This crust is not one organism, but a complex mix of microbes, fungi, lichens and their by-products. This creates a crust of soil particles held together by organic materials.

In healthy habitat, this crust is really what holds the whole system together. It stabilizes the soil, preventing wind and water erosion, and providing an ideal environment for native forbs and shrubs. This stable, undisturbed soil also inhibits weed infestations from cheat grass and other non-native plants.

The biological crust improves water infiltration in the soil, and helps the soils remain at optimal temperature for plant growth. At times subtle, at times a beautiful tapestry, in a healthy system this crust covers all ground not covered by vascular plants.

“It is unappreciated but it provides so many essential functions that are not noticed,” says Colson, who also teaches a class on soil crusts at the Boise Foothills Learning Center . “It’s also extremely fragile.”

The crust can be damaged by improper grazing management, off-road vehicles and even too many human visitors. Damaging the crust, though, damages the whole system and will eventually impact the animals and plants that live there.

“The biological crust plays the same role as mulch in a garden,” says Bureau of Land Management botanist Roger Rosentreter. “As our civilization drifts farther and farther from agriculture, we don’t recognize the importance of things like mulching. But this mulch plays a very important role in the health of plants, including wild plants.”

The Conservancy is currently developing tools to protect the entire sagebrush ecosystem, a much more complex system than most realize. “People see lots of sagebrush, so they don’t realize just how much this habitat is degraded,” says Colson. “I think educating people what healthy sagebrush habitat looks like is vitally important to our conservation efforts.”

And healthy sagebrush includes not only familiar charismatic species, but also small sagebrush-dependent songbirds, rare plants, endemic reptiles. And biological soil crust.

“I know species like sage grouse are rightfully in the spotlight, but there are other species inhabiting sagebrush country that most people don’t even know exist,” says Colson. “Interest is increasing in sagebrush conservation. The Nature Conservancy is developing innovative tools that protect the entire habitat.”