Biocrusts of Northern Arizona National Monuments Post 3: Walnut Canyon

This is my third post on the theme of biocrusts in the National Monuments of Northern Arizona. Find a lichen key here, and a moss key here. Walnut Canyon, Wupatki, Sunset Crater, Montezuma Castle (& Well), and Tuzigoot were sampled.

Walnut Canyon- Of the National Monuments sampled above the Mogollon rim, Walnut Canyon is where BSCs are most consistently important.

We sampled intermediate precipitation portions of the Walnut Canyon rim that had been fenced since at least 1974. We also used surrogate sites with Kaibab limestone parent materials in range exclosures near Flagstaff, and on the south rim of the Grand Canyon to capture more variance in climate parameters. In general, we found that the entire canyon rim likely has potential for BSC cover . Even in sites known to have burned relatively recently, we were able to find some BSC development.

            We made the simplifying assumption that the canyon bottom was unavailable to BSCs due to flooding, and that the canyon walls were too steep to afford more than minimal available habitat. North facing slopes supporting Douglas fir stands were examined and found to contain very little BSC habitat. We did observe the mosses S. ruralis and Brachythecium sp., growing along with the lichen Cladonia fimbriata primarily growing in rock crevices and on organic matter. Because of the steep rocky terrain, very low available BSC habitat, and the low spatial extent of these habitats, we chose not to formally survey them.

The entire Walnut Canyon Rim has potential to support BSCs, regardless of the vegetation type. a)  A cyanobacterial-lichen BSC amidst ponderosa pine litter in a  ponderosa pine habitat (inset). b) A cyanobacterial-lichen BSC between Bouteloua gracilis, and surface rocks in an open grassy pinyon-juniper savannah (inset)