Low impact trekking wasn't my primary learning objective for the Plymouth State University students accompanying me on a travel study course to the Four Corners region of the U.S. However, as an environmental educator, treading lightly and responsibly is certainly an important message I want to convey to others. The Bioregional Outdoor Education Project staff of the Four Corners Outdoor School, our hosts for the course, helped set the stage at the beginning of our trip. They communicated and modeled a respectful environmental ethic in all our activities, especially with regards to low impact camping in a heavily used corridor along a river in a high desert environment. For instance, we picked up any wayward food scraps from our outdoor feasts so as not to attract ants to the most favorable camping sites for those following us down the San Juan River.
It wasn't until we decided to hike the Devil's Garden Trail in Arches National Park at the end of the trip, that I really became curious about the vulnerability of biological soil crusts- a new concept that surfaced in our trip out West- our river guides mentioned it. However, while in Arches, it's hard to look at your feet and worry about conservation, when there are such spectacular, colorful vistas drawing the eyes upward. It was only on returning home that I finally had time to investigate biological soil crusts in more depth. Fortunately, the Visitor Guide to Arches National Park included an informative article which was a starting point for my research on the topic.
I was particularly intrigued about the collection of constituents making up the cryptobiotic soil- cyanobacteria, mosses, soil lichens, green algae, microfungi and bacteria (Arches National Park Visitor Guide, Vol.1, No.8, 205, Canyonlands Natural History Association, www.cnha.org, pg 6). Soil crust is estimated to cover almost 75 percent of the Colorado Plateau and is considered to be alive and ecologically important. Cyanobacteria is considered to be the most prevalent and important constituent. "When filaments of cyanobacteria are moistened, they advance through the soil, leaving sheaths of sticky mucilage on their trail. These gluey filaments bind to soil particles and, over time, can create an erosion-resistant surface," (Arches National Park Visitor Guide, Vol.1, No.8, 205, Canyonlands Natural History Association, www.cnha.org, pg 6). This description of cyanobacteria reminded me of slugs leaving a trail of slime. I was intrigued to learn more about this aspect of biology; cyanobacteria had not been part of my earth science education. An inquiring mind requires interdisciplinary research.
Cyanobacteria are microscopic, photosynthesizing organisms, rich in chemical diversity, and some forms were once classified as blue green algae. Motile species have some microbiologists referring to them as "gliding bacteria" for their peculiar locomotion habits. Photosynthetic pigments can impart a host of different colors-yellow, red, violet, green, deep blue and blue-green... Cyanobacteria may be single-celled or colonial and are among the easiest microfossils to recognize, being larger than other bacteria. Some have remained the same for billions of years. Cyanobacteria also have the useful trait of being able to capture nitrogen from the air and can then convert it to a form plants can use. So, cyanobacteria serve as a fertilizer in this way- a useful trait in an ecosystem notoriously poor in nitrogen. The sticky sheaths described above also bind to calcium, potassium, and manganese making these nutrients available to plants in a useable form. "When wet, the sheaths will expand to ten times their dry size, enabling the soil crust to retain more moisture." So, biological crusts provide stable soil, nutrients, and moisture. The term biological soil crust, also called cryptobiotic crust, emphasizes that these areas are "formed by living organisms and their by-products, creating a crust of soil particles bound together by organic materials" (soilcrust.org).
Back to trekking in the high desert in Arches National Park, when wayward foot steps trod upon the sheaths, they can be destroyed and the cyanobacteria as part of a delicate microsystem cease to function. So, the once "biological" crust is no longer fulfilling its vital roles. Pieces break off and are blown away by the wind. Loose sand covers the remaining biological crust blocking sunlight and photosynthesis stops. It is really important to stay on marked trails, walk on solid rock, or in drainages so as not to impact the biological crusts. The motto while in Arches is don't "bust the crust". Reminding hikers to leave no trace while exploring the Colorado Plateau takes on a special meaning and requires a new kind of vigilance in watching where one walks.
For most of us New Englanders, biological soil crusts are a novelty as they are a feature of arid environments. The closest connection we can make is with fragile, above timberline, alpine terrains that harbor rare plants- one of the reasons that the White Mountain National Forest doesn't allow geo-caching in it's boundaries.
I have seen media headlines, "Are We Loving Our Parks to Death?" I wondered if raising awareness about biological soil crusts figured into any VERP studies. VERP which stands for Visitor Experience and Resource Protection is a new focus for our public parks. Arches National Park has been part of a VERP study, in the last few years, which looks at visitor impacts as well as visitor perceptions; asking visitors what number of people seen on the trail is an â€œacceptable numberâ€? before they begin to feel crowded. They are shown computer-generated photos of the trail, each with an increasing number of people on them. The results help park managers make decisions. Reading about VERP reminded me of a new policy I'd heard about being instituted in the White Mountain National Forest; group sizes larger than 10 are discouraged from hiking trails, to help maintain a quality experience for all. Were certain visitor policies being universally shared across our public lands? How much attention was being paid to biological soil crusts. I did discover Soilcrust.org, a website dedicated to the topic.
I lived in Arizona from 1983-1987 and had never heard of biological soil crusts. So, I wondered when the term was coined, who did the research, and how it was conducted. Could I find and line up a scientist at Arches or in the area who could inform my next group of students to the region about this important concept. I personally wanted a closer glimpse into the world of cryptosoils so I could become a more informed, passionate advocate for protecting these fragile systems.