A Vascular Plant Inventory of the Eastern San Juan Mountains and Vicinity in Southern Colorado

 

By Jeanette Flaig

Masters in Botany

University of Wyoming

 

 

The initiation of this project occurred somewhat serendipitously.  My husband and I had been residents of California for the prior 2.5 years, and while he was at a job he enjoyed, I was trying to decide what to do with my life.  I decided to do what I knew I wanted to do and that was to do a floristic inventory of the Rocky Mountains in Colorado, as this was where I grew up, but I wanted to be in a somewhat remote setting.  I contacted Ron Hartman, curator of the Rocky Mountain Herbarium (RM) and made an appointment.  He put me in touch with a couple graduate students, one being Melanie Arnett.  Melanie mentioned the Eastern San Juan Mountain project, just south of her project as being available.  I knew this is where I wanted to be.  However, following my meeting with Ron, I found out that the project had already been awarded to another student.  So, I decided not to start school until the following spring (2004); however, as circumstances began to unfold, and untold events occurred, I received a call from Ron in May asking if I wanted THE project.  That is the Eastern San Juan project.  And if so, could I start the inventories that summer (2003), in June.  Wow, that would mean some fast packing and moving, as well as leaving my husband for some time.  Well, that is the history, and I am so very thankful for the opportunity I had, to spend two wonderfully fulfilling summers collecting plants in the Eastern San Juan Mountains (ESJ) of Colorado.   

 

The Rocky Mountain Herbarium (RM) has been involved in intensive floristic inventories since 1978.  During this time, fieldwork on 49 major projects has been completed.   A total of 38 graduate students (contributing roughly 68 percent of the collections), Ron Hartman and Ernie Nelson (contributing roughly 32 percent), and other collectors have amassed 518,292 collections during this period for the RM (Hartman and Nelson 2007).  The ESJ is part of a larger effort to map and database the flora of the Southern Rocky Mountains in collaboration with other herbaria on the Front Range, thus creating an electronic atlas of the Rocky Mountain region.

 

As I have already stated, this vascular plant inventory took place in southern Colorado, in the Eastern San Juan Mountains (ESJ) and vicinity during the summers of 2003 and 2004.  The ESJ area is a large expanse that spans most of the Rio Grande National Forest (RGNF) and the eastern half of the San Juan National Forest (SJNF) comprising roughly 5,000 square miles.  Within the circumscription of the project there are three wilderness areas:the Weminuche, the La Garita, and the South San Juan.  The ESJ encompasses all or part of eight counties including Saguache, Rio Grande, Conejos, Archuleta, Mineral, Hinsdale, San Juan, and La Plata counties.

 

 

                   

 

 

The ESJ is a region of high, rugged peaks ranging in elevation from 6,280 feet in the southwest corner (Piedra River)to 14,083 ft. atop Eolus Peak.  The ESJ form an outlying group in the southern Rocky Mountains, contiguous with mountain ranges from central New Mexico northward through Colorado to southern Wyoming (Atwood and Mather 1932).   Four peaks exceeding 14,000 feet ( Eolus , North Eolus , Sunlight , and Windom) , reside within the San Juan National Forest, and numerous 12,000 and 13,000 ft peaks are found within the area.  There are a diversity of land forms, including foothills, mesas, plateaus, buttes, valleys, precipitous canyons, and broad, gently sloping intermontane basins.    

 

As a general rule, topography dictated the method of my collecting.  And if you have ever studied a map of the San Juans you will understand when I say, “due to the significant relief” of the ESJ, I did most of my collecting on foot.  Collecting occurred within each habitat type encountered until I had representative specimens of all vascular plants in flower or fruit.  Sites that were accessible by vehicle were sampled at 5- to 10-mile intervals and collecting was done at the initial site, and subsequently at one or more stops to ensure collection of taxa not encountered previously.  Using this technique, which is the technique of the RM (Hartman and Nelson 1992, 2005), all vegetation types throughout the area are sampled repeatedly during the growing seasons; however collecting sites are rarely revisited and are spaced to ensure maximum coverage of the project area.            

 

I collected on habitat types that I encountered during each season; however the collecting of alpine plants was considered to be of utmost importance during my second year in the field.  This effort was precipitated by an article by Krajick (2004) on the effects of global change and its effects on plant life.  Thus, we felt there was a need for increased base-line data from the alpine.  Consequently, I expended extra effort in climbing to alpine areas and peaks where feasible during my second season.  In the beginning of the second season, when snow prevented me from venturing into high places, I spent additional sampling time on the forest periphery and public lands (BLM).  Ernie Nelson and Ron Hartman also spent considerable time at lower elevations throughout the growing season.

 

An important aspect of this project was to document plant species of conservation concern.  A total of seven candidate species and 37 species of global and state status were documented from 116 study sites.  Thirteen of these sensitive taxa are also endemics.  Below is a list of the 7 candidate species and where they were found.                        

 

Astragalus brandegeei (Brandegee Milkvetch) was collected in a Pinyon Pine woodland with scattered Ponderosa Pine at an elevation of 8,791 feet.  It has been documented in four Colorado counties: Conejos, Fremont, Gunnison, and Mineral (CNHP 1999).  This specimen was found in Saguache County on the East Slope of the Continental Divide (CD).  Astragalus brandegeei also occurs in Arizona, New Mexico, and Utah (CNHP 1999).             

 

Astragalus proximus (Aztec Milkvetch) was found in shale and sandstone outcrops within a Ponderosa Pine forest with Quercus gambelii and Fendlera rupicola understory between 6,430-6,900 feet.  This species was collected on the West Slope of the CD and has been found to occur in both Archuleta and La Plata counties of Colorado (CNHP 1999).  Documented occurrences are also found in New Mexico (CNHP 1999).              

 

Astragalus ripleyi (Ripley Milkvetch) was collected at three different localities on the East Slope of the CD.  The habitats of these occurrences include a grassland and shrubland community, a rocky slope adjacent to a conifer forest and grassland community, and a mixed conifer forest.  Elevation ranges were between 8,467 to 9,800 feet.  The only previously documented occurrence in Colorado was from Conejos County; however it also has been found in New Mexico (CNHP 1999).            

 

Cleome multicaulis (Slender Spiderflower) was found on the East Slope of the CD and occurs in saline or alkaline soils between 7,500-8,000 ft.  This specimen was collected around an oasis on private property where the water is captured in a pool and two ponds.  Documented occurrences of this plant are Alamosa, Costilla, Rio Grande, and Saguache counties (CNHP 1999).  Cleome multicaulis also occurs in Arizona, New Mexico, Texas, Wyoming, and Mexico (CNHP 1999).             

 

Draba smithii (Smith Whitlow-grass) is a Colorado endemic.  Four collections were made on the East Slope of the CD between 9,729-11,805 feet.  Habitat sites include a dry and slightly shaded aspen forest, a heavily grazed spruce forest, an alpine fellfield, and a logged forest.  Documented occurrences of this plant are Custer, Las Animas, Mineral and Saguache counties (CNHP 1999).           

 

Machaeranthera coloradoensis (Colorado Tansy-aster) was collected on the East Slope of the CD between 9,818-12,600 feet.  These specimens were found on shallow soils near rock outcrops or on gravelly slopes and open areas.  Documented county occurrences in Colorado are Gunnison, Hinsdale, La Plata, Lake, Mineral, Park, Pitkin, Saguache, and San Juan (CNHP 1999).  Additional collections during this inventory were made in Rio Grande County.  Machaeranthera coloradoensis  is also documented in South Central Wyoming (CNHP 1999).             

 

Neoparrya lithophila (Rock-loving Aletes) was a Colorado endemic occurring on the East Slope of the CD until 2006.  Collections were documented on rocky north and west exposures in rock-outcrops within and around Pinyon Pine woodlands ranging between 7,869 -9,328 feet.  One collection was found in a very shaded area of a rock-outcrop within a pocket of Ponderosa Pine.  County occurrences are Chaffee, Conejos, Fremont, Huerfano, Rio Grande, and Saguache (CNHP 1999).  One collection during this inventory was also made in Mineral County.  As of 2006, Neoparrya lithophila is no longer endemic to Colorado (Hartman et al 2006). 

 

Additionally during this inventory, 18 noxious weeds were documented. In the Colorado Noxious Weed Act (1996), noxious weeds are defined as “plant species that are not indigenous (non-native) to  Colorado and meet one of several criteria regarding their negative impacts upon crops, native plant communities, livestock, and the management of natural or agricultural systems.”  Hieracium aurantiacum is the only species detected that occurs on the A list.  Of the remaining 17 species, 12 are on the B list and 5 are on the C list. 

 

As a result of this inventory a total of 11,019 specimens of vascular plants were collected for the Rio Grande and San Juan National forests and vicinity during 2003 and 2004.  Of these, a total of 1,074 are unique taxa.  This inventory vouchered 46 sensitive species, 18 Colorado endemics, 114 non-native taxa, 18 noxious weeds, and 8 hybrid taxa.  The total number of collections for the Rio Grande National Forest was 8,182, for the San Juan, 3,223. 

 

Many thanks go to the Rio Grande National Forest (RGNF) and the San Juan National Forest (SJNF) for their monetary contribution.  Additional funding for this project was provided by the Aven Nelson Fellowship in Systematic Botany at the University of Wyoming, and the John Marr Fund and the Myrna P. Steinkamp Memorial Fund; the latter two awards both granted from the Colorado Native Plant Society.  I am deeply grateful to all my contributors.

 

 

References cited:

 

Atwood, W. W. and K. F. Mather. 1932.  "Physiography and Quaternary Geology of the San Juan Mountains, Colorado".  U. S. Dept. Interior.  Professional Paper 166. U. S. Govt. Printing Office, Washington, D.C.

 

Colorado Natural Heritage Program.  "List of Imperiled Species by County and Statewide Species and Natural Community Tracking List".  http://www.cnhp.colostate.edu/

 

Hartman, R. L. and B. E. Nelson.  2007.  Rocky Mountain Herbarium.  University of Wyoming, Laramie.

 

Hartman, R. L., B. E. Nelson, B. Reif, and B. Jacobs.  2006.  "New Vascular Plant Records for New Mexico".  Sida 22: 1225-1233.

 

Hartman, R. L. and B. E. Nelson.  2005.  "General Information for Floristics Proposals".  University of Wyoming, Laramie.  http://www.rmh.uwyo.edu/ 

 

Hartman, R. L. 1992.  "The Rocky Mountain Herbarium, Associated Floristic Inventory, and the Flora of the Rocky Mountains Project".  J. Idaho Acad. Sci. 28:22-43.

 

Krajick, D.  2004.  "Climate Change: All Downhill from Here?"  Science 303:1600-1602.