Astragalus ripleyi - Barneby
Ripley's Milkvetch
Other Common Names: Ripley's milkvetch
Taxonomic Status: Accepted
Related ITIS Name(s): Astragalus ripleyi Barneby (TSN 25660)
Unique Identifier: ELEMENT_GLOBAL.2.129822
Element Code: PDFAB0F7N0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Astragalus
Check this box to expand all report sections:
Concept Reference
Help
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Astragalus ripleyi
Conservation Status
Help

NatureServe Status

Global Status: G3
Global Status Last Reviewed: 13May1997
Global Status Last Changed: 13May1997
Rounded Global Status: G3 - Vulnerable
Reasons: Astragalus ripleyi is a regional endemic found only in Conejos County, Colorado and Taos and Rio Arriba Counties, New Mexico. About 42 reported occurrences with a total of approximately 4,500 individuals existed as of May 1997. In September 2002, the total number of occurrences have increased to approximately 38 in New Mexico and more than 50 in Colorado. However some of these occurrences may not be extant (see threat information). There are no known protected occurrences.
Nation: United States
National Status: N3

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Colorado (S2), New Mexico (S3?)

Other Statuses

Comments on USESA: In 1990, the US Fish and Wildlife Service (USFW) nominated Astragalus ripleyi as a candidate for listing as threatened or endangered, Category 2. In 1996 USFW discontinued the use of Category 2 as a species designation and there are no current plans to list Astragalus ripleyi (USFW 1996).

NatureServe Global Conservation Status Factors

Range Extent Comments: Astragalus ripleyi is known from Taos and Rio Arriba counties in New Mexico and Conejos County, Colorado. The total range is approximately 975 square miles, an area approximately 65 miles long by 15 miles wide, along the volcanic rim of the San Luis Valley, from near Monte Vista, Colorado to Tres Piedras and Questa, New Mexico (Lightfoot 1995). Within its range it is locally abundant in some years. However, it has a patchy distribution and is not found in all potential habitat. Its distribution is consistent with it being a substrate endemic associated with the San Juan volcanic field (Tweto 1978).

Number of Occurrences: 21 - 300
Number of Occurrences Comments: In September 2002, the total number of occurrences have increased to approximately 38 in New Mexico and more than 50 in Colorado. However some of these occurrences may not be extant (see threat information).

Population Size Comments: The estimated total number of individuals for this species is approximately 10,000; a majority of the occurrence records report abundance. This species will be more abundant during years with above average precipitation (especially late winter and spring precipitation).

Overall Threat Impact Comments: Some of the possible threats to A. ripleyi include widespread fire suppression, grazing especially by domestic sheep, competition from invasive weed species and activities such as off road vehicle traffic and logging that contribute to soil disturbance, soil compaction, and soil erosion. Agricultural conversion and urban development has likely impacted some populations in the past and may in the future.

A history of widespread fire suppression within A. ripleyi range may have had a negative impact on available habitat and thus abundance because it grows in forest and woodland clearings and is likely excluded by mature tree canopy closure.

Astragalus ripleyi is very palatable to all herbivores. Arthropods, rodents, wildlife such as elk, deer and rabbits, and livestock such as cows, sheep, and goats all browse upon it. Livestock grazing appears to be a significant threat due to the obvious palatability of the stems and the observed grazing activity at Astragalus ripleyi sites (Naumann 1990, Lightfoot 1995). Because of the large size of cattle and elk these large mammals have a heavy impact on any plants that they eat. The fact that Astragalus ripleyi frequently grows in the center of a shrub where they are protected from large herbivores has been cited as evidence of either livestock or elk grazing pressures (Naumann 1990, Lightfoot 1995, Burt 1997, S.L. O'Kane pers. comm. 2002). With no grazing pressure plants grow taller than 3 feet high (Weber 1955). Herbivory is likely to cause a decline in seed production because Astragalus ripleyi does not compensate for vegetative loss with new growth (Burt 1999). However, reproduction and recruitment is likely not paramount to the survival of this long-lived perennial and populations may persist in the presence of seasonal-rotational livestock grazing. There is no information on the palatability of Astragalus ripleyi to bighorn sheep. Astragalus ripleyi is palatable to domestic sheep, which eat plants down to the ground and domestic sheep may be more detrimental to long-term survival than either cattle or elk (Braun 1988, Lightfoot 1995). One report indicated that arthropod herbivory was more of a threat than livestock and wildlife herbivory, but was only based on one year of data (Burt 1997). Subsequent studies indicated that all herbivory, especially by rodents, could be equally detrimental and that environmental conditions were important in determining the degree of injury to a population (Burt 1999).

Invasive weed species are another significant threat. Interspecific competition is a problem, especially with yellow sweet clover and white clover (Naumann 1990, G. Long pers. comm. 2001). Populations have declined in size, or been eliminated, at sites that have been invaded by sweet yellow clover and white clover (G. Long pers. comm. 2002).

Current evidence suggests that logging and firewood cutting per se is not harmful and are likely to open up potential habitat for Astragalus ripleyi. However, the ground disturbance associated with such activities may have very deleterious consequences. The root is particularly important for long-term persistence and soil erosion and activities disturbing the top centimeters of the ground surface, such as off-road-vehicle (ORV) recreation as well as logging, may be particularly detrimental. Active soil erosion is currently threatening a population in the Rio Grande National Forest (J. Burt pers. comm. 2002). A small occurrence has been reported growing in a small arroyo (Tonne and Sivinski 2000). It is likely that such populations would be especially vulnerable to erosive forces such as flash flooding.

Road building and road widening activities may also have had impacts on populations. Astragalus ripleyi was reported to be common along Highway 44 (Weber 1955) but few plants have been observed within the last decade (D. Erhard pers. comm. 2002, J. Burt pers. comm. 2002). In Colorado, only Federally listed species are protected on right-of-ways managed by the Department of Transportation (J. Powell pers. comm. 2002). In New Mexico, plants have been observed in areas with roadside construction (Braun 1988, R. Romero pers. comm. 2002). Road maintenance practices are not known to have directly impacted Astragalus ripleyi. Mowing is unlikely to have any short-term impacts. Yearly mowing during the growing season may eliminate viable seed production and so may have detrimental consequences over the long term. The impacts of herbicide use have not been evaluated. Sites with potential habitat that had been treated in the past with the herbicide, tebuthiuron, were surveyed and no plants were found at any of the sites (Braun, 1988). However, it was not known if plants were there before chemical treatment so no conclusions can be made. Some populations that occur in sagebrush associations may be periodically impacted by brush control operations (Sivinski and Lightfoot 1995).

Long-term Trend:  
Long-term Trend Comments: Astragalus ripleyi was discovered and described relatively recently and there are few "historical occurrences". There are insufficient numerical data to definitively determine the long-term trends. Unfortunately, until more recently, the numbers of individuals were not counted or even estimated when populations were found. In the 1980s and 1990s, as more areas within its geographic range were searched and agency personnel become more familiar with the species, the numbers of documented occurrences increased (Braun 1988, Romero 1992, Lightfoot 1995). Within the last decade more than 24 new occurrences have been reported (CNHP and NMNHP element occurrence records 2002).
Population trends are particularly difficult to predict for this species from observations made periodically over relatively short periods of time because there is evidence that the numbers of plants at a given site will vary considerably from year to year in response to environmental conditions, tending to be higher in years with above average precipitation. (Burt 1998). In New Mexico between 1988/1989 and 1992 the abundance at several sites significantly increased (Romero 1992). For example, approximately 20 plants were estimated per site on the Tres Piedras district in the Carson National Forest in 1988 and 1989 in contrast to the survey results conducted in 1991 and 1992 when "hundreds" were reported per site (Romero 1992). In contrast, approximately 100 plants were observed in the Mogote area of the BLM San Luis RA, Colorado, in 1987 but no plants could be found after a substantial search in 1989 (Naumann 1990). In addition, despite 3 days of thorough searching at three sites in the Rio Grande National Forest that were previously documented with over 100 individuals in 1990, each had less than 20 individuals in 1996 (Burt 1997). The differences at each site are likely due to the above average rainfall in 1990, 1991, 1992 compared to the dry years of late 1980s and 1996 (Romero 1992, Burt 1997, 1999). Weber (1955) described A. ripleyi as a "common and conspicuous plant along the roadside between Antonito and the base of Cumbres Pass". However, Astragalus ripleyi has been rarely observed along this route in the last decade (J. Burt pers. comm. 2002, D. Erhard pers. comm. 2002). It is possible that the 1955 observation was during a wet cycle and that subsequent surveys along that route may have been in "dry" periods. However, disturbance on the right of ways associated with road widening activities, and the invasion of yellow sweet clover may have significantly impacted those roadside populations. Historic populations are likely impacted by agricultural conversion particularly in Conejos County, Colorado.
In Colorado, there are a total of 23 occurrences that have been visited twice or more times at one or more years apart. Of those 23 occurrences, 10 only noted the presence of the plants at each visit. Where numbers were counted or estimated at each visit, there was an increase reported at 8 occurrences and a decrease at 4 occurrences, at one of which no plants were found during the most recent visit. In 2001, surveys were made at two sites where Astragalus ripleyi had been documented in an area of Ra Jadero Canyon designated a "Colorado Natural Area". No plants were found at either site (R. Karges pers. comm. 2002). Apparently a "gradient of grazing impact" was evident over the area and the reason that Astragalus ripleyi was absent was speculated to be herbivory (R. Karges pers. comm. 2002).

Intrinsic Vulnerability Comments: A. ripleyi appears to be somewhat tolerant of disturbance. There are several extant occurrences that were first documented in the 1950's. Plants appear to tolerate moderate grazing but may be more vulnerable to secondary effects such as increased erosion.

Other NatureServe Conservation Status Information

Distribution
Help
Global Range: Astragalus ripleyi is known from Taos and Rio Arriba counties in New Mexico and Conejos County, Colorado. The total range is approximately 975 square miles, an area approximately 65 miles long by 15 miles wide, along the volcanic rim of the San Luis Valley, from near Monte Vista, Colorado to Tres Piedras and Questa, New Mexico (Lightfoot 1995). Within its range it is locally abundant in some years. However, it has a patchy distribution and is not found in all potential habitat. Its distribution is consistent with it being a substrate endemic associated with the San Juan volcanic field (Tweto 1978).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States CO, NM

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CO Conejos (08021)
NM Rio Arriba (35039), Taos (35055)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
13 Alamosa-Trinchera (13010002)+, Conejos (13010005)+, Upper Rio Grande (13020101)+, Rio Chama (13020102)+
14 Upper San Juan (14080101)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Help
Basic Description: Astragalus ripleyi is an erect herbaceous perennial with stems from 40 to 100 cm (16 to 36 inches) tall. The root system is from a subterranean crown (Barneby 1952, Isely 1998). The stems branch prolifically above a simple fistular, or tubular, base. The root system has been described as rhizomatous (Barneby 1952, Isely 1998). However, even though stems from the same plant may be 10 cm away from each other, Burt (1997) concluded there was no evidence of a true rhizomatous root system. It has 13 to 19 narrow linear-oblong, somewhat folded leaflets that are essentially hairless on the upper surface. The herbage otherwise has appressed pubescence (flat-laying hairs). The nodding flowers are a lemon, creamy, yellow and the large, blade-like pods are pendulous with conspicuously long stalks, or "stipes" (Barneby 1952, Martin and Hutchins 1980). Within its range it is recognizable by its robust habit, pale yellow reflexed flowers and, especially, the pendulous, exerted flat pods with a stalk-like (stipitate) base (Isely, 1998). Astragalus ripleyi blooms from June into July.

Technical Description: After Barneby (1964) and Iseley (1998): Tall and robust perennial, strigulose nearly throughout with fine, straight, appressed hairs up to 0.35-0.5mm long; the herbage greenish-cinereous. The stems few, 1-6 from a subterranean crown, erect, basally leafless, 40-100 cm long. The leafstalk 4-10 cm long; leaflets ca. 13-17 (19), linear-oblong, 8-10 mm, flat and marginally involute, glabrous above, the terminal one commonly continuous with the leafstalk; stipules free. Inflorescence exserted, loose, with numerous, soon spreading and nodding flowers. Calyx tube cylindric, 5-6.5 mm, mixed dark and light strigulose; lobes 0.5-1mm. Corolla 14-17 mm, lemon-yellow. Ovules ca.10-15. Fruits spreading to deflexed, exerted-stipitate 8-15 mm long, unilocular, persistent; body oblong-lanceolate, laterally compressed and flat, 2-3 cm x 4-6 mm; valves papery, reticulate at maturity, scantily strigulose. Seeds yellowish-brown, rugulose-punctate, dull, 2.8-3.4 mm long.
Diagnostic Characteristics: Astragalus ripleyi can be distinguished from the two other tall sympatric Astragalus species by several characteristics. Astragalus ripleyi has more than 11 leaflets and the stipitate pods are laterally compressed. Astragalus lonchocarpus has 1 to 9 leaflets and the pods are dorsiventrally compressed(Barneby 1964, Spackman et al. 1997). Astragalus drumondii has dense, spreading pubescence and its pods are trigonous (triangular) in cross-section (Heil and Herring 1999). Astragalus lonchocarpus and Astragalus ripleyi have been mistaken for each other during field surveys.
Reproduction Comments: Astragalus species are generally insect pollinated (Geer and Tepidino 1993) and Astragalus ripleyi appears to be no exception. Bees and ants have been observed on flowers and Burt (1997) reported that bumblebees (Bombus ternaries) were the most common arthropod visitor. As part of the same study Burt (1997) bagged flowering stems to exclude pollinators and these produced no fruits whereas the unbagged stems did. This may indicate some degree of self-incompatibility exists or that flowers up the same stem did not mature at same time. Although this observation provides indirect support for incompatibility in Astragalus ripleyi, because no hand pollinations were performed, the environment of the pollination bag may have caused sterility and cannot be completely discounted.

Astragalus ripleyi flowers from June into July. The earliest date flowers have been reported is June 5. Within a population, a high percentage, frequently on the order of 80 to 90 percent, of individuals produce flowers and pods (Romero 1992, CNHP and NMNHP element occurrence data). Fruits tend to be persistent on the plant through at least October (Lightfoot 1995). The patchy nature of its spatial distribution suggests seed dispersal may often be limited and localized around the parent plant. Seed dispersal has been speculated by ants, mice and other seed storers, tumbling dispersal of dried plants, and wind or water transport although little evidence has been documented for any particular mechanism (Braun 1988, Naumann 1990, Lightfoot 1995, J. Anderson pers. comm. 2002). Rodents cache fruits in small piles near plants (Burt 1999).

There is no evidence of hybridization between Astragalus ripleyi with other Astragalus species. The sympatric Astragalus lonchocarpus is closely related but no intermediates have been observed (Lightfoot 1995).

Ecology Comments: Astragalus ripleyi behaves as a long-lived individual that primarily allocates resources into survival of the individual rather than into reproduction (Burt 1997, 1998, 1999). It does not compensate for herbivore activity by producing more stems or leaves to replace those which are lost but tends to produce fewer reproductive organs and, presumably, builds up root stock reserves for subsequent years growth. The habitat of Astragalus ripleyi, namely in open savannahs and shrublands, open canopy ponderosa pine forest, and along the edges of closed canopy forests and woodlands, suggests that it is a mid-successional species. It rarely occurs in recently disturbed sites such as road cuts but is frequently found in areas that have disturbance, such as fire, recorded within a decade. It likely benefits from an intermediate disturbance regime and in pre-settlement times Astragalus ripleyi may have occupied habitats that were periodically opened up by fire (Naumann 1990, Lightfoot 1995).

Burt (1999) reported a correlation between precipitation and number of stems observed at each site. The observations indicated an increase occurred between 1996 and 1997 and a net increase between 1996 and 1998. However, there was intervening decrease in population size between 1997 and 1998. This variation emphasizes the importance of multiple year monitoring. In addition, although precipitation is often ascribed to explain variation in population size, as measured by above-ground stems, the precipitation in 1996 and 1998 did not appear substantially different. It may be that the heavy snowfall in April was particularly important in stimulating stem growth in 1998. This observation suggests that it is not only total precipitation but also when precipitation occurs, and perhaps the form in which the moisture occurs, that is significant. Another factor to consider in interpreting the trend is that precipitation records are for the general region and local precipitation levels may differ.

There are no data on longevity of seed or seed bank dynamics. The degree of reported seed predation by insects is variable but may be a cause of significant seed loss in some years (Coles 1996, Burt 1997). Evidence of seed predation can be found in some herbarium specimens, for example collected by O'Kane (1996) at the University of Colorado Herbarium (COLO) that had "pin-prick" holes, most likely present prior to collection, in the legumes. There is no information on seedling ecology and the rates of recruitment and mortality are unknown. Few age and size class data are available but plants with large, robust and flowering stems one year will appear small and immature the next (Burt 1999). This observation makes casual comments on seedling presence difficult to evaluate.

No studies have been undertaken to determine the genetic structure of either range-wide or local populations. Studies undertaken on the Rio Grande National Forest collected some valuable demographic data over a period of three years (Burt 1997, 1998, 1999). Unfortunately only limited conclusions can be drawn as the data was not fully analyzed, but some deductions and inferences can be made. From observations made during this three-year study, it is clear that individuals do not follow a linear progression from seedling to non-reproductive individual to reproductive individual but may be reproductive one year, small vegetative plants the next, or may remain dormant for at least one year without any above ground stem (Burt 1999). From observations made on the Rio Grande and Carson National Forests (G. Long pers. comm. 2002, J. Burt pers. comm. 2002) it is likely that patches of Astraglus ripleyi roots lie essentially dormant under canopy cover and sprout when suitable conditions recur. For example, within a "couple of weeks" of a burn on the Carson Forest stems of Astragalus ripleyi were observed in areas where no plants were documented in the past (G. Long pers. comm. 2002). Astragalus ripleyi stems were likely from pre-existing root stocks because precipitation appeared to be inadequate for seed germination and no other annual species were observed in the burn areas. Although roots appear to undergo dormancy for extended periods, direct evidence is only available to support a dormancy period of two years. Plants tagged in 1996 did not reappear in 1997 but came up in 1998 despite there being a high amount of moisture in 1997 (Burt 1998).

Habitat Comments: Astragalus ripleyi occurs in the the Great Basin and Coniferous Woodland sections of the Southern Rocky Mountain province (Fenneman 1946, McNab and Avers 1994). In Colorado, the habitat is generally open ponderosa pine-Arizona fescue savanna (Pinus ponderosa-Festuca arizonica association), in open-canopy pinon-juniper (PJ) woodlands with an Arizona fescue (Festuca arizonica) understory, and on the edges of closed-canopy ponderosa pine and mixed conifer forest (Lightfoot 1995). In New Mexico, habitat seems a little more variable and occurrences are frequently in shrub-dominated habitat such as pine-oak (Quercus gambellii) communities, pinon-juniper sagebrush, sagebrush communities, and Chrysothamnus viscidflorus meadows.
Astragalus ripleyi is often observed growing under the canopy, or amongst the stems, of shrubs such as big sage (Artemisia tridentata), gambel oak (Quercus gambellii), rabbit brush (Chrysothamnus sp.), and juniper (Juniperus sp.). The association with shrubs may be due to a favorable microclimate or advantageous soil environment for germination and seedling establishment. In addition, or alternatively, growing in the midst of shrubs affords protection from large herbivores and may be a consequence of current or historical grazing pressures (Naumann 1990, Lightfoot 1995, R.A. Sivinski pers. comm. 2002). In one severely overgrazed, very weedy Chrysothamnus viscidiflorus meadow that had apparently been planted with Agropyron cristatum in the past, Astragalus ripleyi plants were confined to large shrubs. The entire meadow appeared to be similar habitat but the plants were only in a few clumps. This observation, made in 1998 (Colorado Natural Heritage Program element occurrence records accessed in 2002), suggests that either some habitat modification is tolerated or that habitat is not strictly confined to the limited types described in the past (Naumann 1990, Lightfoot 1995). It is unclear as to how many years had past since the grass seeding took place and one may conjecture that the root systems were present prior to habitat modification and that the surviving plants are relics.
A noteworthy observation is that Astragalus ripleyi invariably grows in areas where plant species diversity is high (Braun 1988). Tree species associated with Astragalus ripleyi habitat are Abies concolor, Juniperus monosperma, Juniperus osteosperma, Juniperus scopulorum, Pinus edulis, Pinus ponderosa, Populus tremuloides, and Pseudotsuga menziesii. Associated shrub species include: Artemisia frigida, Artemisia nova, Artemisia tridentata, Chrysothamnus greenei, Chrysothamnus naseosus, Cercocarpus montanus, Potentilla fructicosa, Symphoricarpus oreophilus, Rhus trilobata, and Quercus gambellii. Associated forb species include: Antennaria sp., Aster bigelovii, Astragalus drummondii, Astragalus hallii, Astragalus lonchocarpus, Calohotus sp. Castilleja sp., Gutierrezia sarothrae, Heterotheca villosa, Hymenoxys odorata, Picradenia richardsonii, Erigeron sp. Eriogonum sp., Eriogomun racemosum, Linium lewisii, Melilotus sp., Melilotus officinalis, Gilia sp. Oxytrophis lambertii, Penstemon griffinii, Penstemon secundiflorus, Taraxacum officinale, and Vicia americana. Associated grass and grass-like species include: Agropyron cristatum, Agropyron trachycaulum, Agropyron smithii, Blepharoneuron tricholepis, Bouteloua gracilis, Bromus tectorum, Carex sp, Danthonia intermedia, Elymus elymoides, Festuca arizonica, Festuca ovina, Festuca thurberi, Koeleria sp., Muhlenbergia sp., Muhlenbergia filiculmis, Muhlenbergia montana, Oryzopsis micrantha, Poa fendleriana, Poa pratensis, Stipa sp., Stipa comata, and Stipa hymenoides.
Plants occur at elevations between at 5,459 ft to 9,360 ft (1,664m to 2,835m). This is a considerable extension from the 7,000 to 8,250 feet range reported by Barneby (1964). However, where elevation was reported, the majority of occurrences are between 8,500 and 8,999 ft. Plants are found on level ground to slopes of approximately 30% with the most occurrences occurring on slopes of 10% or less. Although it has been found on slopes facing all aspects, northerly aspects were most common among the occurrences where aspect was reported. This, and a tendency to find them in east-west trending drainages, may imply a preference for more mesic sites in otherwise relatively dry environments.

Astragalus ripleyi occurs exclusively on volcanic derived soils associated with the San Juan volcanic field (Erhard 1994, Lightfoot 1995). In New Mexico, the soils that overlay volcanic rock are generally loamy mixed soils. One report in New Mexico (USFW ACSS 1993, New Mexico Natural Heritage Program element occurrence records accessed in 2001) indicates that plants grow in loamy clays overlying granitic bedrock but the town-range-section information places the occurrence on volcanically-derived soils. The occurrence is most likely on soils derived from plutonic rocks that are characteristically medium- to coarse-grained granitic textured (geological code: Xp, Anderson et al. 1997). Soils on this geological formation may well appear "granitic" rather than "volcanic" in the field. The precision of the occurrence data was such that it may, alternatively, be on the adjacent Los Pinos geological formation (geological code: Tlp) that comprises volcaniclastic conglomerate interbedded with basaltic flows (Anderson et al. 1997).

Economic Attributes
Help
Economically Important Genus: Y
Economic Comments: This species has no known economic value. Work to identify the natural phytoalexins (fungal toxins) in Astragalus ripleyi was undertaken by the US Department of Agriculture (S. Martin pers. comm. 2002). Spores of the fungus, Helminthosporium carbonum, elicited production of maackiain, an isoflavan phytoalexin, in Astragalus ripleyi leaves (S. Martin pers. comm. 2002).
Management Summary
Help
Stewardship Overview: Astragalus ripleyi is a regional endemic that is restricted to soils derived from volcanic formations. Given its limited range, populations are currently vulnerable to habitat alteration resulting from agricultural and urban development. Astragalus ripleyi appears inherently vulnerable to herbivores - being palatable to insects, diverse wildlife species, and livestock. Sheep grazing may be particularly harmful but light to moderate use by livestock and wildlife does not seem unduly detrimental especially if a seasonal-rotational system is practiced. Long-term fire suppression appears to have influenced the distribution and abundance of this species. Mature canopy cover appears to exclude Astragalus ripleyi. The degree to which long-term fire suppression has adversely impacted the range and abundance of this species largely depends upon several unknown factors, namely; the longevity of the root systems, the frequency of seedling recruitment, and seed dispersal pattern. Current evidence suggests seedling recruitment is infrequent and seeds have a restricted dispersal pattern. In this case, both characteristics lead to vulnerability to the consequences of fire suppression. Although it does not colonize newly disturbed sites, its apparent requirement for a relatively open canopy suggests that it benefits from some disturbance. However, whereas fire disturbance may be beneficial, significant soil disturbance and progressive soil erosion is likely very detrimental because its long-lived root system appears to be the mechanism whereby populations survive. Active and severe soil erosion currently threatens at least one occurrence. Weed infestation has been cited as a threat and sweet yellow clover (Melilotus officinalis) that has been sown within its range to re-vegetate land may be particularly detrimental. If competition from an exotic forb species is leading to a decline in habitat, manual removal may be required since no selective herbicides are available.

Some current beneficial management practices include: a rest rotation system for moderate cattle grazing intensity, maintaining some areas with populations of Astragalus ripleyi primarily for elk winter range, minimizing off road vehicle traffic in occupied and potential habitat, and performing logging and wood-cutting activities during winter. At the most basic level, management may best focus on maintaining the current canopy composition and community structure.

Monitoring of populations and individuals is required to determine the status (overall and by site) and to define population trends. These activities should be restricted to times of year when the plant has pods, and preferably flowers. Flowers are helpful in picking out plants in what can otherwise be a "sea of green". Although A. ripleyi is globally rare, it is frequently locally abundant. This local abundance is often misleading in the perception of its rarity and may lead to decisions based only on a local scale. However, this local abundance also allows for limited experimentation of different management practices on larger populations. In addition to monitoring populations per se, the habitat should be monitored, especially changes in canopy cover. Permanent changes in site hydrology should also be noted as drying may negatively impact the habitat.

One important reason to continue monitoring and studying this regional endemic species is actually because of its apparent resilience to many land use practices. If population trends begin to show a steady decline or contraction of range over several years it may be indicative that a fundamental problem is occurring with the ecology of a particular region. This long-lived perennial may be a "barometer" of changes in the ecosystem and although it cannot be determined how its abundance and range has been affected over the last century, with the current understanding of its ecology and biology on which to build, it may be a valuable species to monitor in the future.

Species Impacts: Astragalus ripleyi has no known impacts on other species.
Restoration Potential: Relatively little information exists on the life history or the critical abiotic and biotic conditions that ensure successful establishment of A. ripleyi populations. It is difficult to assess the potential for success of artificially established populations. Scarified seeds germinate readily in the year they are produced (Burt 1999) however natural scarification may take several years to occur. Studies on seed germination rates have not been published but two unpublished reports suggest germination rates are good. An informal report described approximately 33 per cent of seeds germinated (S. Martin pers. comm. 2002) and another reported 78 to 80 per cent of scarified seeds germinated within 3 to 14 days in a greenhouse (Burt 1999). Burt (1997) observed that only scarified seed germinated and such mandatory scarification would be expected as many members of the Leguminosae have a hard, impermeable seed coat (Bewley and Black 1982). Seedling establishment was very poor in both Astraglus ripleyi seed germination studies (S. Martin pers. comm. 2002, Burt 1999). Inappropriate soil conditions or inadequate moisture were speculated to be the cause of poor seedling establishment. Astragalus ripleyi has a large root system and it is unknown if transplanting would be successful. Timing may be very important for transplanting. It is likely that plants should be collected before sprouting in early spring. The association between A. ripleyi roots and soil microbes has not been documented. Association with a species of Rhizobium is likely since Astragalus lonchocarpus, a closely related species, was reported to be nodulated (Allen and Allen 1981).
Preserve Selection & Design Considerations: Preserve design considerations should be based on the site conservation goals for the specific site. These goals may focus on the A. ripleyi population, the vegetation community, or the ecosystem, and should be clear and concise with measurable results.
ECOLOGICAL INFORMATION: The best available ecological and biological information should be used in decision making. A decision on what constitutes a viable population needs to be determined on a site-by-site basis (see GHABCOM and GECOLCOM sections of this ESA). The total number of occurrences, and their relative conditions should also be considered. Individuals and small clumps of Astragalus ripleyi are often distributed throughout several acres. The degree of interaction between these small patches is not well described or understood.
Monitoring may reveal the appropriate level of the various age classes needed to provide for the continual existence of the population. The appropriate composition of the various age classes needed to provide for the continual existence of the population is not clear. As mentioned above (see GECOLCOM section of this ESA), Astragalus ripleyi individuals do not follow a linear progression from seedling to non-reproductive individual to reproductive individual but may be robust and reproductive one year, small vegetative plants the next, or may remain dormant for at least one year without any above ground stem. Specific investigation into the spatial dynamics of the species should be included in monitoring. Monitoring should also be used to indicate the extent of threats from exotics. For the community, selected members (for example grass, shrub and tree canopy cover) may be targeted for monitoring or management activities.
Development of a model that represents stages (life cycle), processes succession, disturbance), and threats to A. ripleyi or its associated community will help in producing a comprehensive site design. Construction of a model may be useful for understanding the threats and population conditions. The combination of a model and threats analysis will set the stage for conservation strategies.
CONSERVATION ZONES: Conservation zones include all processes needed to protect a population over the long-term.
THREATS: Threats must be assessed at each occurrence. One goal of any site conservation plan is to eliminate or mitigate threats. Threats may come from any source and may be environmental (process related) or demographic. Site design considerations should include hydrologic, sedimentation, and natural and unnatural disturbance parameters.
Astragalus ripleyi occurrence sites appear to be strongly influenced by tree canopy cover and the presence of competitive species. Plant habitat/occurrence areas are likely best if a patchwork of clearings and wooded area is maintained. Astragalus ripleyi is very susceptible to herbivory and additional pressures of domestic livestock grazing to the natural predation by elk, rodents and arthropods should be considered. Competitive species such as Meliotis and other weeds appear to out-compete A. ripleyi. Monitoring should be used to indicate the extent of threats from exotics.
MEASURES of SUCCESS: A method for determination of the level of success should be developed in order to determine if goals and objectives were met, to evaluate the conservation strategies used, and to determine directions for future conservation actions.

Management Requirements: Relatively little is known of the conditions necessary for reproduction, dispersion, establishment, and maintenance of A. ripleyi and therefore critical assessment of potential management plans may be difficult. Many management decisions have been made based upon anecdotal reports. Changes in tree canopy and community composition should be monitored. There appears to be a requirement for open canopy but the evidence is correlative rather than experimental. Because of the importance of the long-lived root-system, disturbance of soils should be avoided. If competition from an exotic species, such as Melilotis, is leading to a decline in habitat, manual removal is recommended. Changes in site hydrology are a concern as drying may negatively impact the habitat. The relationship between precipitation and stem number indicates that a long-term drying trend at a site is likely to have a negative impact.
Light to moderate cattle grazing may be compatible with maintaining Astragalus ripleyi populations if a seasonal-rotational system is practiced. Studies on a similar species, Astragalus scaphoides, indicated that high stocking rates during periods of growth, or other management practices that lowers growth and survival of individuals, will have a much more detrimental effect than seed loss on population viability (Lesica 1995). The studies also showed that while repeated spring grazing is detrimental, rotation-grazing systems in which spring grazing occurs only one in three years appear to be compatible with the long-term persistence of A. scaphoides populations (Lesica 1995).
Although A. ripleyi is globally rare, it is locally abundant. This local abundance is often misleading in the perception of its rarity and may lead to decisions based only on a local scale. However, this local abundance may allow for limited experimentation of different management practices on larger occurrences. Management might otherwise focus on maintaining the current canopy cover and community structure.

Monitoring Requirements: Determination of the monitoring protocol will be defined by the monitoring objective on a site-by-site basis. The best method of monitoring the population is determined by 1) what information is required to adequately address the management objective for a particular site, and 2) on the time and resources available for monitoring. Monitoring may be on one of three levels of monitoring of a combination of any level.

^Level I: Qualitative or semi-quantitative information. Presence/absence, population boundary demarcation, number estimate, and permanent photo-points are all relatively rapid methods of monitoring such sites. Even though Astragalus ripleyi is not rhizomatous, the multiple stems that appear to be unrelated above ground can actually belong to the same plant (J. Burt pers. comm. 2002). This condition may lead to an overestimation of not only individuals but also in the potential for genetic diversity within a population.

^Level II: Quantitative measures of population/community: number of individuals or stage class, density, percent cover, frequency, permanent or non-permanent transects. Life cycle status could be observed during flowering and fruiting periods. In-depth monitoring would track seedlings and mature plants, and sources of mortality. At this level the goal is to monitor sub-samples to detect changes in a larger population over a long time period, such as observing the effects of changing canopy cover, and permanent monitoring plots will run into the problems associated with auto-correlation (Goldsmith 1991). To minimize such problems, monitoring protocols for species with a spatially aggregated, or patchy, distribution have been described by Elzinga et al. (1998) and Goldsmith (1991).

^Level III: Permanent monitoring plots with marked individuals were established on the Rio Grande National Forest in the late 1990s. The aim was to learn more about the transition probabilities associated with the life cycle and the effects of herbivory. Astragalus ripleyi is a long-lived species and populations are unlikely to be very spatially dynamic. Following the fate of individual plants in permanent plots is an excellent way to monitor an occurrence and make demographic studies. This method is suitable for small populations and subsets of larger populations. Care should be taken not to damage the roots of the plants when placing stakes.


Management Programs: There are few formal management plans written that directly address Ripley's milkvetch. Currently management of the species appears essentially subject to the individual land managers' personal knowledge and the continuity of management strategy (for example during staff turnover) is not assured. There are no formal monitoring studies ongoing at the current time(September 2002).

References to A. ripley management were made in "The Revised Land and Resource Management Plan for the Rio Grande National Forest" (USFS 1996) and a "Special Interest Area" was created for Astragalus ripleyi. An amendment was made to this plan in 1999 (USFS 1999). Mitigation recommendations were to "avoid timber harvest and prescribed fire in potential Astragalus ripleyi [Ripley milkvetch] habitat (i.e., open ponderosa pine/Arizona fescue stands with some Douglas fir where canopy coverage by trees is less than 25%)" and "keep timber harvest and prescribed fire above the 9,200 feet contour line in the Analysis Area to protect Astragalus ripleyi". It is unclear as to how an appropriate patchwork of open and closed canopy cover is maintained in this area. A sensitive plant guide was developed for Rio Grande National Forest to assist field crews in recognizing Astragalus ripleyi (Erhard 1994).

A draft of the Bureau of Land Management (BLM) San Luis Resource Management Plan (1989) mentioned Astragalus ripleyi occurred within the resource area but made no specific management recommendations. Few monitoring or survey activities occur on the La Jara Resource district but plans for development projects consider Astragalus ripleyi if the species is known from past inventories to exist within the development area (M. Castle pers. comm. 2002). In 1991, the San Luis Management Plan was approved designating the Ra Jadero Canyon in Conejos County, Colorado, an area of critical environmental concern (ACEC). The area was also designated a Colorado Natural Area in 1996 (Colorado Natural Areas Program web site 2002). ACEC designation gives BLM authority to provide special management to unique species or other significant natural resources. At the present time there are no formal management protocols or plans specifically for Astragalus ripleyi. Mechanized vehicle traffic is limited by season and also restricted to designated roads and trails within the ACEC (BLM 1991). Ra Jadero Canyon ACEC is currently managed by the BLM La Jara Resource Area, which was formerly part of the BLM San Luis Resource Area. An adjacent tract of land owned by the State Land Board has been placed under a Stewardship Trust and also designated a Colorado Natural Area by the Colorado Natural Areas Program partly because of the known populations of Astragalus ripleyi (K. Page pers. comm. 2002, Colorado Natural Areas Program Stewardship Trust Nomination undated). Some protection is afforded this species in this area. For example, logging activities are restricted to winter months to minimize soil disturbance. The Colorado Natural Areas Program has appointed a steward for the Ra jadero Canyon Colorado Natural Area and periodically the sites are surveyed for Astragalus ripleyi (R. Karges pers. comm. 2002).

The Colorado Division of Wildlife does not have a management plan for either of the areas where Astragalus ripleyi occurs on their property and they do not currently consider the species when managing the areas (K. Navo pers. comm. 2002). However, it is anticipated that a management plan will be written within the next few years for one area that currently, and in the foreseeable future, provides winter range for elk and deer but does not permit livestock grazing. Astragalus ripleyi may be considered in this management plan although it is unlikely that Astragalus ripleyi is significantly impacted under present management practices.


Monitoring Programs: No active monitoring programs exist for Astragalus ripleyi at the present time. However, monitoring plots were established in the late 1990s in the Rio Grande National Forest, Colorado, and utilizing them and the data previously collected will facilitate trend analyses and status assessment of the species when funds become available. Several theories on how Astragalus ripleyi responds to management practices, for example it becomes excluded by a closed canopy, have become accepted. However, the theories still need to be rigorously examined and it is essential to monitor populations that will be impacted by a land use, such as prescribed burns and logging. A current example is one on State land in Colorado. Logging is taking place in a known population of Astragalus ripleyi. With the information available, the land manager decided logging activity must be only be performed during the winter months (K. Page pers. comm. 2002). If it is solely canopy opening that benefits populations, the prediction is that stem abundance will increase because soil disturbance should be minimal in winter and the elimination of ponderosa pine canopy should be beneficial (see "GECOLCOM" section). However, precise knowledge of the number and state of the population prior to the disturbance is lacking. If studies had been conducted on the population at least one, if not several, years before and be initiated for several years after the disturbance the information gained would be invaluable. Similarly, when prescribed burns take place it is constructive to survey the area in advance at an appropriate time of year to determine if populations are observed and then follow up with surveys or monitoring activities for several years subsequent to the burn. When setting up a monitoring study it is critical to define the goals.

Astraglus ripleyi requires monitoring to determine its current status (overall and by site) and population trend. The best method of monitoring is dependent on the time and funding available and needs to be determined on a site specific basis (see MONIT.REQS).

Contacts for management programs include:
Dean Erhard. USDA Forest Service, Rio Grande National Forest, Monte Vista, Colorado.
Karges, Robert. Colorado Natural Areas Program Steward, Colorado Springs, Colorado.
Navo, Kurt. Colorado Division of Wildlife, La Jara, Colorado.

Management Research Programs: No current research on management programs exist for this species. However the Rio Grande National Forest has sponsored a program in the past. Contact: Erhard, Dean. US Forest Service, Rio Grande National Forest, Colorado.

Management Research Needs: The importance of fire in the life history of A. ripleyi should be rigorously examined. Determining the consequence of modifying canopy cover, either an increase or decrease, on plant vigor and abundance is important when considering how to manage the species. In addition, comparing reduction of cover mechanically versus by fire would also aid in understanding the importance of edaphic conditions to A. ripleyi abundance. Soil chemistry may be very important to A. ripleyi establishment.

The potential for interaction between the consequences of fire and herbivory should be examined. Leigh and Holgate (1979) reported the mortality rate for palatable species on sites that experienced both burning and post fire grazing was double the mortality rate for sites that experienced either factor alone. In addition, mortality on burned-only or grazed-only plots was not much different than on control plots. Another indirect consequence of fire that may negatively impact a palatable species is that herbivores tend to congregate on patches where vegetation has burned (Whelan 1997).

Additional topics: Individuals knowledgeable of this species include:
Dean Erhard. USDA Forest Service, Rio Grande National Forest, Monte Vista, Colorado.
Robert Sivinski. New Mexico Forestry and Resources Conservation Division, Santa Fe, New Mexico.
Population/Occurrence Delineation
Help
Minimum Criteria for an Occurrence: Any naturally occurring population that is separated by a sufficient distance or barrier from a neighboring population.
Separation Barriers: As a guideline, EOs are separated by either: 1 mile or more across unsuitable habitat or altered and unsuitable areas; or 2 miles or more across apparently suitable habitat not known to be occupied.
Separation Distance for Unsuitable Habitat: 1.61 km
Separation Distance for Suitable Habitat: 3.22 km
Separation Justification: Justification: The rationale for this large a separation distance across suitable but apparently unoccupied habitat is that it is likely additional research will find this habitat to be occupied. It can often be assumed that apparently unconnected populations will eventually be found to be more closely connected; these are best regarded as suboccurrences. No information on mobility of pollen and propagules is available on which to base the separation distance for this species.
Date: 27Sep2000
Author: Spackman, S., and D. Anderson
Population/Occurrence Viability
Help
Excellent Viability: Size: 500 or more individuals (based on available EOR data). Condition: the occurrence has an excellent likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. This occurrence should be in a high-quality site with less than 1% cover of exotic plant species and/or no significant anthropogenic disturbance. Landscape Context: the occurrence is surrounded by an area that is unfragmented and includes the ecological processes needed to sustain this species. Periodic fire may be necessary to maintain appropriate tree and shrub density in the matrix community in which this species is found.
Good Viability: Size: 100 to 500 individuals (based on available EOR data). Condition: the occurrence should have a good likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. Anthropogenic disturbance within the occurrence is minimal. If exotic species are present, they comprise less than 10% of the total ground cover. Landscape Context: the surrounding landscape should contain the ecological processes needed to sustain the occurrence but may be fragmented and/or impacted by humans.
Fair Viability: Size: 20 to 100 individuals (based on available EOR data). Condition: The occurrence may be less productive than the above situations, but is still viable, with multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. The occupied habitat is somewhat degraded (exotic plant species make up between 10-50% of the total ground cover and/or there is a moderate level of anthropogenic disturbance). Landscape Context: there may be significant human disturbance, but the ecological processes needed to sustain the species are still intact.
Poor Viability: Size: Less than 20 individuals (based on available EOR data). Condition: little or no evidence of successful reproduction is observed (poor seedling recruitment, no flowering or fruiting observed, or poor age class distribution). Exotic plant species make up greater than 50% of the total ground cover, and/or there is a significant level of human disturbance. Landscape context: the surrounding area is fragmented with many ecological processes no longer intact. The occurrence has a low probability of long-term persistence due to inbreeding depression, natural stochastic events, and its intrinsic vulnerability to human impacts.
Justification: A Rank: Large populations in high quality sites are presumed to contain a high degree of genetic variability, to have a low susceptibility to the effects of inbreeding depression, and to be relatively resilient.

C Rank: EOs not meeting "C"-rank criteria are likely to have a very high probability of inbreeding depression and extirpation due to natural stochastic processes and/or occur in degraded habitat with low long-term potential for survival.

Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
Date: 27Sep2000
Author: Spackman, S., and D. Anderson
Notes: COHP
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
Help
Authors/Contributors
Help
NatureServe Conservation Status Factors Edition Date: 29Oct2002
NatureServe Conservation Status Factors Author: J. A. R. Ladyman
Management Information Edition Date: 29Oct2002
Management Information Edition Author: J. A. R. Ladyman
Management Information Acknowledgments: My thanks to the Colorado Natural Heritage Program, in particular Susan Spackman and David Anderson, and the Colorado Natural Areas Program, in particular Ron West, for their generosity in making their files and records available. I also appreciate access to the files and assistance given to me by Andrew Krantz, Region 2 Forest Service, and Chuck Davis, US Fish and Wildlife Service. I also very much appreciate the documents sent to me by Charlie McDonald, Region 3 Forest Service, Albuquerque, Carol Dawson, Bureau of Land Management, Denver, and Robert Sivinski, New Mexico Forestry and Resources Conservation Division, Santa Fe. Information provided by the New Mexico Natural Heritage Program was very valuable. NatureServe, Arlington, Virginia provided funding to the author for the development of this ESA.
Element Ecology & Life History Edition Date: 29Oct2002
Element Ecology & Life History Author(s): J. A. R. Ladyman

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
Help
  • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.


  • Allen, O.N. and E.K. Allen. 1981. The Leguminosae: A source book of characteristics, uses and nodulation. The Univ. of Wisconsin Press, Madison, WI.

  • Anderson, O.J., G.E. Jones, G.N. Green. 1997. Geologic map of New Mexico. USGS Open-file report OF-97_05, Digital database by G.N. Green and G.E. Jones. New Mexico Bureau of Mines and Mineral Resources, US Geological Survey, Department of Interior, Albuquerque, New Mexico, USA.

  • Barneby, R. C. 1952. Pugillus Astragalorum XIV: Notes on Sect. Lonchocarpi. Leaflets of Western Botany. 6(9): 172-176.

  • Barneby, R. C. 1964. Atlas of North American Astragalus. Memoirs of New York Botanical Garden, vol. 13. New York Botanical Garden, Bronx, NY.

  • Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.

  • Bewley, J.D. and M. Black. 1982. The release from dormancy. In: Physiology and Biochemistry of Seeds in relation to germination. Vol. 2. p. 184-198. Springer-Verlag, Berlin, Germany.

  • Braun, R.P. 1988. Inventory of Astragalus ripleyi on the Carson National Forest. Unpublished manuscript.

  • Braun, R.P. 1988. Inventory of Astragalus ripleyi on the Carson National Forest. Unpublished manuscript.

  • Bureau of Land Management (BLM). 1989. San Luis Resource Management Plan and Environmental Impact Statement - Draft. Unpublished Report. September. US Department of Interior, Bureau of Land Management, Denver, Colorado, USA.

  • Bureau of Land Management (BLM). 1991. San Luis Resource Area Record of Decision and Approved Resource Management Plan. December. Unpublished Report. US Department of Interior, Bureau of Land Management, Denver, Colorado, USA.

  • Burt, J. 1997. The effects of grazing and fire on Astragalus ripleyi Barneby. Unpublished document. February 15. Submitted to the Colorado Natural Areas Program, Denver, Colorado, USA.

  • Burt, J. 1998. Effects of grazing and fire on Astragalus ripleyi Barneby; summary of 1997 field work. Unpublished document. June 15. Submitted to U.S.D.A. Forest Service, Rio Grande National Forest, Colorado, USA.

  • Burt, J. 1999. Effects of grazing and fire on Astragalus ripleyi Barneby; summary of 1998 field work. Unpublished document. March 15. Submitted to U.S.D.A. Forest Service, Rio Grande National Forest, Colorado, USA.

  • Coles, J. 1996. Population trends in Astragalus ripleyi on Forest service Lands. Unpublished document. Colorado Natural Areas Program, Denver, Colorado, USA.

  • Colorado Bureau of Land Management. 2004. State Director's Sensitive Species List, updated May 4, 2000. Colorado Bureau of Land Management, Denver Colorado. Available at http://www.co.blm.gov/botany/sens_species.htm (Accessed September 2002).

  • Colorado Natural Areas Program. 2002. Internet site: http://parks.state.co.us/cnap/index.html. Colorado Natural Areas Program, Denver, Colorado, USA. [Accessed September 2002]

  • Elzinga, C.L., D.W. Salzer and J.W. Willoughby. 1998. Measuring and monitoring plant populations. Bureau of Land Management Technical Reference 1730-1. US Department of Interior, Bureau of Land Management, Denver, Colorado, USA.

  • Erhard, D. 1994. Threatened, Endangered, and Sensitive Plant Guide, Rio Grande National Forest. Limited issue publication. US Forest Service, Rio Grand National Forest, Monte Vista, Colorado, USA.

  • Fenneman, N.M. 1946. Physical divisions of the United States (map). US Geological Survey, Reston, Virginia, USA.

  • Geer, S.M. and V.J. Tepedino. 1993. Breeding systems of the rare heliotrope milkvetch (Astraglus montii Welsh: Fabaceae) and two common congeners. In: Proceedings of the southwestern rare and endangered plant conference. Based on the conference held March 30-April 2, 1992. R. Sivinski and K. Lightfoot (eds). Misc. Publication No. 2. New Mexico Forestry and Resources Conservation Division, Energy, Mineral and Natural Resources Department, Santa Fe, New Mexico, USA.

  • Goldsmith, F.B. 1991. Monitoring for Conservation and Ecology. Chapman and Hall, New York, New York, USA.

  • Heil, K. and J. Herring. 1999. Astragalus ripleyi, (Ripley's milkvetch). In: New Mexico Rare Plants Home Page (Version 15 March 2002), New Mexico Rare Plant Technical Council, New Mexico Rare Plants, Albuquerque, New Mexico. Internet site: http://nmrareplants.unm.edu/reports/astrip.htm [Accessed September 2002].

  • Isely, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States (exclusive of Alaska and Hawaii). Monte L. Bean Life Science Museum, Brigham Young University; MLBM Press, Provo, Utah. 1007 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Leigh, J.H. and M.D. Holgate. 1979. Responses of understorey forests and woodlands of the southern tablelands to grazing and burning. Australian Journal of Ecology. 4: 25-45.

  • Lesica P. 1995a. Demography of Astragalus scaphoides and the effects of herbivory on population growth. Great Basin Naturalist 55(2): 142-150.

  • Lightfoot, K. 1995. Status report on Astragalus ripleyi Barneby. September 26. Unpublished document. Forestry and Resources Conservation Division, Santa Fe, New Mexico, USA.

  • Martin, W.C., and C.R. Hutchins. 1980-1981. A flora of New Mexico. 1980, Vol. 1; 1981, Vol. 2. J. Cramer, in der A.R. Gantner Verlag, K.G., Vaduz, Liechtenstein. 2591 pp.

  • McNab,W.H. and P.E. Avers. 1994. Ecological subregions of the United States: Section descriptions. Administrative Publication WO-WSA-5. U.S. Department of Agriculture Forest Service. Washington, DC, USA.

  • Naumann, T. 1990. Status Report for Astragalus ripleyi. Unpublished report. June 29. Colorado Natural Areas Program, Division of Parks and Outdoor Recreation, Denver, Colorado, USA.

  • Naumann, T.S. 1990 a. Status report for Astragalus ripleyi Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

  • Romero, B. 1992. Astragalus Report. Internal USDA Forest Service Document. 8/28/92. Tres Piedras Ranger District, Carson National Forest, New Mexico, USA.

  • Sivinski, R. and K. Lightfoot 1995. Inventory of rare and endangered plants of New Mexico. Misc. Publication No. 4. New Mexico Forestry and Resources Conservation Division, Energy, Mineral and Natural Resources Department, Santa Fe, New Mexico, USA.

  • Sivinski, R. and K. Lightfoot. 1992. Inventory of rare and endangered plants of New Mexico. New Mexico Forestry and Resources Conservation Division, Energy, Mineral and Natural Resources Department, Santa Fe, New Mexico, USA.

  • Spackman, S., B. Jennings, J. Coles, C. Dawson, M. Minton, A. Kratz, and C. Spurrier. 1997. Colorado rare plant field guide. Prepared for Bureau of Land Management, U.S. Forest Service and U.S. Fish and Wildlife Service by Colorado Natural Heritage Program.

  • State of New Mexico. 1998. "Inventory of Rare and Endangered Plants of New Mexico", under Section 1, Section 9-10-10 NMSA 1998, Plant Endangered Species Act, as revised, NMFRCD Rule No. 91-1, December, 1991.

  • Tonne, P. and R. Sivinski. 2000. State Land Surveys 1999-2000. Unpublished document. New Mexico Forestry and Resources Conservation Division, Energy, Mineral and natural resources Department, Santa Fe, New Mexico, USA.

  • Tweto, O. 1978. Geologic map of Colorado. US Geological Survey, Denver, Colorado, USA.

  • U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened wildlife and plants. Federal register 55(35):6190. February 21.

  • U.S. Fish and Wildlife Service (USFWS). 1996. Endangered and threatened wildlife and plants; review of plant and animal taxa that are candidates for listing as endangered or threatened species. Federal Register 61(40):7596-7613. February 28.

  • U.S. Fish and Wildlife Service Assistant Colorado State Supervisor (USFW ACSS). 1993. Memorandum to Chief, Endangered Species/Environmental Contaminants, Region 6. Subject: Report on San Luis Valley Interagency Field Trips, July 6 and 8, 1993.

  • U.S. Forest Service (USFS). 1989. Implementation plan for the management of Astragalus ripleyi on the Carson National Forest. February 1989. Unpublished document. Carson National Forest, Tres Piedras, New Mexico, USA.

  • U.S. Forest Service (USFS). 1993. Region 2 Regional Forester Sensitive Species List, 1993. Available at http://roadless.fs.fed.us/documents/feis/data/sheets/summspd/tes_supp/r2_ssspecies.pdf (Accessed September 2002).

  • U.S. Forest Service (USFS). 1996. The Revised Land and Resource Management Plan for the Rio Grande National Forest. Record of Decision. November 7, 1996. Unpublished Document. Rio Grande National Forest, Monte Vista, Colorado, USA.

  • U.S. Forest Service (USFS). 1999. Decision notice and finding of no significant impact - November Analysis Area. June 18. USDA Forest Service, San-Juan-Rio Grande National Forests, Conejos Peak Ranger District, Monte Vista, Colorado.

  • USDA, NRCS. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

  • Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Eastern Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 555 pp.

  • Weber, W.A. 1955. Additions to the Flora of Colorado, II. Univ. of Colorado Studies, Series in Biology, No. 3: 65-108 (v. p 92).

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2018.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2018 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.