SENSITIVE SPECIES EVALUATION FORM Astragalus anisus, Priority 1. Astragalus anisus M.E. Jones (ASAN4). Gunnison milkvetch. CNHP G2 / S2, Track A FS: R2. BLM: CO-GN -- G2 N2. CO S2. GMUG-Paonia, Taylor River-Cebolla Confi- Criteria Rank dence Rationale Sources of Information Doesn’t match any of the described ratings, distribution in R-2 doesn’t look like any My observations, Weber and Wittmann 1 of the diagrams. One polygon on the R-2 map. Concepts such as “dispersal among 2001a, Barneby 1964, herbaria DENF- patches” and “population isolation” are not important for vascular plants. CS-COLO-RM, CNHP 1999-2002, Distribution NA L NFS available habitat and populations usually occur near the Forest Boundary, and Spackman and others 1999. within R2 across it from larger populations on public lands below. Species only occurs in Colorado: Gunnison and Saguache Counties. My observations, Weber and Wittmann 2 2001a, Barneby 1964, herbaria DENF- Distribution A H CS-COLO-RM, CNHP 1999-2002, outside R2 Spackman and others 1999. Moderate dispersal capability: seeds are large, without any mechanical aids to My observations, Weber and Wittmann dispersal. Pollen dispersal unknown. Mature fruit fuzzy with hairs, but usually on or 2001a, Barneby 1964, Spackman and 3 near ground surface – unlikely to be aided by animals. No ground-dwelling animals on others 1999. Dispersal B M these sites, because they are usually very shallow to a hard clay-rock mix. I have Capability observed a slight amount of wind and water dispersal of the fruit, less than 5 m. Doesn’t match any of the described ratings, “demographic stochasticity” is My observations, Weber and Wittmann apparently irrelevant for vascular plants. 2001a, Barneby 1964, herbaria DENF- 4 Described as “locally abundant,” with 50-60 known locations = populations, ranging CS-COLO-RM, CNHP 1999-2002, Abundance in NA L in size from 150 to >5,000. Local botanists have stopped recording new sites because of Spackman and others 1999. R2 their large number in this area, so I estimate >100 populations with total number of plants >500,000. 10-12 of the populations have been counted more than once, with no declines noted. My observations, Weber and Wittmann One of the largest populations (>5,000 individuals) appears to have increased 2001a, Barneby 1964, herbaria DENF- somewhat; but there has been a large amount of year-to-year variation in number of CS-COLO-RM, CNHP 1999-2002, individuals seen, strongly correlated with seasonal weather patterns. Cool, moist Spackman and others 1999. 5 springs are normally a rare occurrence in the Upper Gunnison Basin, but they have Population B M been happening more frequently lately, which leads to very few of the plants flowering, Trend in R2 so they are hard to count – probably resulting from combination of El Niño, La Niña, and global warming. Weather patterns here are getting much more unpredictable. Populations on NFS are moderate to large in size, away from roads and other potential disturbance factors, and without recent declines in numbers or habitat. Dry gravelly flats and hillsides, in gravelly clay soils, usually among or under black My observations, CNHP 1999-2002, 6 sagebrush, 7,500-8,500 ft. Soils are very shallow to a hard clay-gravel mix. Spackman and others 1999, Johnston and Habitat Trend B H Most of the populations occur on public land, where off-road vehicle use is others 2001. in R2 prohibited. Observations indicate no decline in habitat quantity or quality. Plants are not palatable to any herbivore, and they are resistant to livestock or My observations. 7 herbivore trampling – which is unlikely in these sites because of their low forage Habitat productivity. Vulnerability C M Most of the populations occur on public land, where off-road vehicle use is or prohibited. Modification Plants are prostrate, resistant to trampling. Moderately high level of viable seed My observations. 8 production, indicating a moderately high reproductive rate. Germination requirements Life History C M are assumed to be limiting, but we have no data or observations on this point. and Demographics 1 SENSITIVE SPECIES EVALUATION FORM National Forests in the Rocky Mountain Region where species is KNOWN (K) or LIKELY (L)* to occur: *. Likely is defined as more likely to occur than not occur on the National Forest or Grassland. This generally can be thought of as having a 50% chance or greater of appearing on NFS lands. Formatted COLORADO NF/NG K L K L K L Arapaho-Roosevelt NF NEBRASKA NF/NG WYOMING NF/NG Formatted White River NF Samuel R. McKelvie NF Shoshone NF Routt NF Halsey NF Bighorn NF Grand Mesa Uncompahgre Gunnison NF K Nebraska NF Black Hills NF San Juan NF Ogalala NG Medicine Bow NF Rio Grande NF SOUTH DAKOTA NF/NG Thunder Basin NG Pike-San Isabel NF Black Hills NF KANSAS NF/NG Comanche NG Buffalo Gap NG Cimarron NG Pawnee NG Ft. Pierre NG Taxonomy. Astragalus anisus is accepted by all Colorado botanists as a distinct species. Discussion. Astragalus anisus is a local endemic species, but has many populations, some of them large, and has no apparent threats. Does not seem to be a viability concern as a species or within Region 2. References Barneby, Rupert C. 1964. Atlas of North American Astragalus. Memoirs of the New York Botanical Garden, Volume 13. 1,188 pp. Colorado Natural Heritage Program. 2000a. Data base reports and GIS data for BLM/USFS sensitive species. NFWF Project No. 99-138. Fort Collins, CO: Colorado Natural Heritage Program. 1 CD-ROM, dated September, 2000. Colorado Natural Heritage Program. 2000b. Definition of Natural Heritage rarity ranks. http://www.cnhp.colostate.edu/docs/global.html, downloaded December 5, 2000. Colorado Natural Heritage Program. 2001. Data base reports and GIS data for USFS sensitive species. Fort Collins, CO: Colorado Natural Heritage Program. 1 CD-ROM, dated November, 2001. Harrington, Harold D. 1954. Manual of the plants of Colorado: For the identification of the ferns and flowering plants of the state. Denver, CO: Sage Books. 666 pp. Isely, Duane. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States (exclusive of Alaska and Hawaii). Provo, UT: Brigham Young University, Monte L. Bean Total world-wide distribution of Astragalus anisus (ASAN4). Life Science Museum. 1,007 pp. Johnston, Barry C.; Laurie Huckaby; Terry J. Hughes; and Joseph Pecor. 2001. Ecological types of the Upper Gunnison Basin. Technical Report R2-RR-2001-01, 858 pp. Lakewood, CO: USDA Forest Service, Rocky Mountain Region. Spackman, Susan; Bill Jennings; Janet Coles; Carol Dawson; Mark Minton; Andrew Kratz; Carol Spurrier; Christopher S. Johnson; and Mike Barry. 1999. Colorado rare plant field guide. http://ndis.nrel.colostate.edu/ndis/rareplants/cover.html, last updated March 1, 1999. Weber, William A.; and Ronald C. Wittmann. 2001a. Colorado flora: Western slope, Third Edition. Niwot, CO: Colorado Associated University Press. 488 pp. Author and date: Barry C. Johnston, Botanist, Grand Mesa-Uncompahgre-Gunnison National Forests, 216 N. Colorado St., Gunnison, CO 81230-2197. (970) 642-4467. [email protected]. Last modified September 15, 2002. 2 .