Microbiotic Soil Crusts

Trails on either side of the dark microbiotic crust in Southern Utah demonstrates the value of microbiotic soil crusts and what happens when careless trampling crushes them.


To a farmer, a soil crust is a condition where, like the top crust on a cherry pie, the soil forms a thin but almost impenetrable layer, either chemically or physically. It is harmful in that water may run off instead of filter down and tiny emerging seedlings may not have the strength to power through the crust.

There is another type of soil crust though, one that has many names: cryptobiotic, microfloral, cryptogamic, microphytic and microbiotic; all names that describe features of the crusts and refer to a complex formation of fungi, cyanobacteria, lichens, algae and bryophytes growing together on or just below the soil surface. As the science surrounding these micro-communities has evolved, scientists have gravitated toward the name microbiotic as the most descriptive and accurate term.

Microbiotic crusts form in arid and semi-arid environments around the world. In the United States, they are prominent in the Great Basin, Colorado Plateau, Sonoran Desert, and the inner Columbia Basin. In the Great Basin and Colorado Plateau, they are usually dark-colored and form in clumps rather than a single crust.

In healthy rangelands, microbiotic soil crusts are often abundant. At least one study determined that 70-80 percent of the living cover in some areas consists of these living crusts.

It stands to reason that something this common is an integral component of the environment. Research has demonstrated that microbiotic soil crusts aren’t just a curiosity, a chance amalgam of organisms that may benefit each other but serve no real ecological purpose. Wherever they occur, crust communities are key to maintaining healthy rangelands.

Arid and semi-arid rangelands are different from grasslands. Rangeland plants grow in clumps with significant space between plants. This makes better use of scarce water but leaves a lot of bare soil potentially subject to wind and water erosion. Microbiotic crusts stabilize the soil between plants, thwarting erosion. Some even secrete polysaccharides which essentially glue soil particles together.

Keeping soil in place is just one function of a microbiotic soil crust. These crusts may fix nitrogen, which means that they can literally make soil nitrogen out of thin air, providing this essential nutrient to other plants. That is just the beginning. Microbiotic crusts are also photosynthetic when most plants are dormant adding additional organic carbon to the soil. Research has made it clear that soils with intact microbiotic crusts have  higher organic material, more plants, a wider variety of species of plants and plants with higher nutrient content than soils where crusts have been heavily damaged or removed.

One of the best things about soil crusts is their inherent ability to keep noxious invading plants like cheatgrass and medusahead rye at bay. Native plants that evolved with microbiotic soil crusts often have developed mechanisms that allow their seeds to penetrate microbiotic crusts but invasive species may not have that advantage and their seed may sit on top where it can’t germinate.    

These microbiotic crusts are tough characters, adapted to some pretty nasty conditions. What they don’t tolerate is crushing, whether it is by livestock feet, ATV or bicycle tires or hiking boots. Once damaged, crusts may be able to bounce back, at least in appearance, in as little as five years. To reach full functionality and a complete complement of species may take up to 250 years.

Microbiotic crusts have taken a beating over the past 150 years as human activity has trampled them under foot and wheel. We can’t hope for a better yesterday but we can change the future by being more respectful of this important community in the environment.

 



Help Idaho Wildlife

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

Wildlife License Plates

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program. Go figure. 


"WOW. What a phenomenal piece you wrote. You are amazing." Jennifer Jackson

That is embarrassing but actually a fairly typical response to my nature essays. Since The Best of Nature is created from the very best of 16 years of these nature essays published weekly in the Idaho Falls Post Register (online readership 70,000), The Best of Nature is a fine read. It covers a wide variety of topics including humorous glimpses of nature, philosophy, natural history, and conservation. Readers praise the style, breadth of subject matter and my ability to communicate complex and emotional topics in a relaxed and understandable manner.

Everyone can find something to love in this book. From teenagers to octogenarians, from the coffee shop to the school room, these nature essays are widely read and enjoyed.

Some of the essays here are my personal favorites, others seemed to strike a chord with readers. Most have an important message or lesson that will resonate with you. They are written with a goal to simultaneously entertain and educate about the wonderful workings of nature. Some will make you laugh out loud and others will bring a tear to the eye and warm your heart.

Readers Write:

"You hit a home run with your article on, Big Questions in Nature. It should be required reading for everyone who has lost touch with nature...great job!" Joe Chapman

"We enjoyed your column, Bloom Where Planted. Some of the best writing yet. The Post Register is fortunate to have your weekly columns." Lou Griffin.

To read more and to order a copy, click here or get the Kindle version 

here

Copies are also available at:

Post Register

Barnes and Noble in Idaho Falls

Idaho Falls Chamber of Commerce Visitor Center (425 Capital)

Perfect Light Photo Supply

Work Wearhouse

Museum of Idaho

Valley Books, Jackson Wyoming

Avocet Corner Bookstore, Bear River National Wildlife Refuge, Brigham City, Utah

Craters of the Moon National Monument Bookstore, Arco, Idaho