Rare Plants and Alpine Vegetation of the La Sal Mountains: Studies of a Unique Ecosystem Rising Above the Arid Colorado Plateau Desert
The high peaks of the La Sal Mountains in southeastern Utah (part of the Manti-La Sal National Forest) are a special part of the Colorado Plateau, supporting one of the few true alpine communities in the region. These singular values were formally recognized when the high summits and ridges of Mt. Mellenthin, Mt Peale (at 12,721 feet in elevation), and Mt Tukuhnikivatz were designated as a USDA Forest Service Research Natural Area (RNA) in 1988. The Mt. Peale RNA was established specifically to protect ecosystem structure and function in representative alpine and subalpine habitats. The area represents alpine herb communities, glacial features, and high mountain landforms. Outside of the Uinta Mountains, there is limited RNA representation of true alpine communities in Utah.
The La Sal Mountains’ alpine communities also support several endemic and unique plant species. One Forest Service sensitive plant species, the La Sal daisy (Erigeron mancus), is found nowhere else in the world. There are also at least 10 plant species that represent the only known populations of those species in the state of Utah. They include Podistera eastwoodiae, Oreoxis bakeri, Besseya alpina, Saxifraga bronchialis, and Carex perglobosa. Many of these species have a NatureServe state ranking as imperiled or critically imperiled.
Partnership Assesses Impacts to Alpine Areas
Towering above the outdoor-recreation capital of Moab and two major National Parks, the highest peaks in southeast Utah are a popular place to recreate. In 2008, with a grant from the Canyonlands Natural History Association (CNHA), researchers from the local Moab district of the Manti-La Sal National Forest and researchers from the Rocky Mountain Research Station in Flagstaff, Arizona, began a baseline study to monitor the impacts of recreation on alpine communities of the La Sal Mountains. This study seeks to answer the research question, “Is recreational use of the alpine portions of the La Sal Mountains impacting soil, vegetation, and rare plant resources?”
The alpine vegetation of the La Sal Peaks in the Mt. Peale Research Natural Area (RNA) was systematically sampled, focusing on vegetation and soil conditions. Five broadly defined types of habitat have been identified in the Mt Peale RNA, three in the alpine zone and two in the forested, subalpine zone (100 acres). The well-developed alpine turf communities are uncommon. Combined with the alpine turf-rock community type, there is a total of 360 acres of herbaceous alpine vegetation. The majority of the area is dominated by talus and barren rock (2,020 acres).
The majority of the plots sampled were found in a pristine condition. The impacts noted were largely related to movement/displacement of rocks on steep talus slopes. There were a few areas with user-created trails. Not all the areas were sampled, but the plan is to visit them in the summer of 2009 (when it is hot in the Moab valley) and establish more transects around Mt Peale.
New Rare Plant Findings
The 2008 fieldwork revealed a relatively continuous series of Erigeron mancus patches along the west ridge up to Mt. Laurel, from the talus field at 11,400 ft. to 11,900 feet just above tree line, as well as along the Middle Group crest line at 12,000 feet, more than was anticipated. Other than the formal description of the species and its geographical range, little is known about the population biology of this rare species. The research crew observations indicate that the La Sal daisy can be abundant within its microhabitat niche on dry, windy ridgelines but less abundant to absent on nearby more mesic mid-slopes.
The research crew also collected numerous specimens, collecting quite a diversity of species, including some new ones. Rock columbine, Aquilegia scopulorum, is a new record for the La Sal Mountains. Patterson sagewort, Artemisia pattersonii, is a new record for Utah. These specimens were identified and will be curated at the Rocky Mountain Herbarium in Laramie, Wyoming.
Climate Change Studies of Rare Alpine Plants and Vegetation
In addition to the recreation study, plants of the alpine community will be compared to other established alpine studies, including on the San Francisco Peaks in Arizona and the Rocky Mountains in Colorado. After finding the La Sal daisy population, Dr. James Fowler of the Rocky Mountain Research Station in Flagstaff became excited about the opportunity to do an elevation density gradient study as a way to monitor climate change impacts to alpine plants. Due to another Discovery Grant from CNHA, the research crew will be coming back to do more work on the La Sal mountains in the 2009 summer season.
The work in 2009 will measure the change in density of the La Sal daisy along an elevation gradient on a ridge in the middle group. By measuring patch widths along this transect, the patch size can be calculated, and using density measurements, population size for this area can then be estimated. All vascular plant species will be recorded within each sampling frame along the transect, both to delineate species closely associated with E. mancus and to describe how plant species composition changes from tree line to crest line. This data set will then form a basis for detection of climate change effects with future sampling at 5 to 10 year intervals.
A second exploratory survey involves the snow glade at tree line on the north base of Mt. Mellenthin. Snow glades are defined by late-lying snow (until mid-summer) which restricts conifer establishment. Under a reduced snowfall scenario, this graminoid-dominated habitat may be converted to spruce-fir forest over time. The vascular plant species present within the snow glade will be inventoried and possible future transect locations will be surveyed to detect vegetation shifts due to changes in snowmelt timing.
With numerous peaks over 12,500 feet in elevation, the La Sal Mountains not only provide a stunning visual contrast to the canyonlands of the Colorado Plateau, but also support one of the few true alpine communities in the canyonlands section and a host of rare and endemic plant species. There is growing concern about the potential effects of global climate change on these isolated alpine ecosystems. The La Sal Mountains support many endemic plant species in a Research Natural Area with a management emphasis on research and protection of pristine conditions and biological diversity.
For More Information
Barb Smith, Moab District Wildlife Biologist Manti-La Sal National Forest Moab Ranger District P.O. Box 386 Moab, UT 84532 Ph. 435-259-7155