N. Holmgren
Identity
Unique IDELEMENT_GLOBAL.2.147176
Element CodePDSCR0D050
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderScrophulariales
FamilyOrobanchaceae
GenusCastilleja
Other Common NamesAquarius Paintbrush (EN)
Concept ReferenceKartesz, 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.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-01-07
Change Date1991-07-19
Edition Date2024-12-30
Edition AuthorsRoth, E., rev. J. Niese, rev. B. Franklin (1996), rev. L. Oliver (2005), rev. L. Morse (2005), rev. A. Treher (2016), rev. Johnson, J. (2024)
Threat ImpactHigh
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences6 - 80
Rank ReasonsCastilleja aquariensis is a perennial herb endemic to the Aquarius Plateau and Boulder Mountain in Utah, United States. This species is threatened by grazing livestock that trample and kill the plants and eat the flower buds and plant tops, which limits reproductive capacity. This species appears to be sensitive to droughts and climate change may increase the severity and duration of droughts. Monitoring indicates stable to declining populations across many occurrences.
Range Extent CommentsCastilleja aquariensis is endemic to the Aquarius Plateau, Garfield Co. and Boulder Mountain, Wayne Co., Utah (Groebner 2005). Range extent was estimated to be 390 square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1993 and 2024 (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024). Including observations from 1983 to 1992, the range extent is estimated to be 650 square kilometers (GBIF 2024, NatureServe 2024, SEINet 2024).
Occurrences CommentsBy applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024, it is estimated that there are17 occurrences rangewide (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024). Including observations from 1983 to 1992, the number of occurrences is estimated to be 52 (GBIF 2024, NatureServe 2024, SEINet 2024).
Threat Impact CommentsRoad realignment and other construction related to recreational or timber activities pose potential threats to the species, however, grazing is the greatest threat to this species.
Grazing is the most imminent threat to this species. It has been extensively impacted by domesticated livestock, especially sheep. In areas where sheep are kept, the species has nearly been eliminated and where cattle occur it has been reduced greatly in numbers and reproductive vigor (England 2002). Further, the Aquarius Plateau is considered severely overgrazed by biologists, however, efforts to reduce grazing have been thwarted by livestock grazing permittees. Perpetual grazing puts this species at risk for extirpation in much of its range, leaving it to persist only in less accessible relictual habitats (England 2002). Even the populations in relictual habitats are at threat of being over-grazed given the lack of rangeland for forage and the poor quality of available forage (England 2002). Finally, it is stated that "threat to this species is imminent with the current grazing situation, the relative intensity of the threat will change with proposed alternative grazing systems" (England 2002). Implementation of a recent (1996) management agreement may substantially reduce impacts from grazing (USFWS, 2004). The Forest Service is working to mitigate the effects of grazing by livestock by deferring grazing until after seed has set 1 out of every 3 years in some pastures (pers. comm. J. Stenten).
Information from the Forest Service in 2006 indicated that population numbers and vigor were lowest in areas where there is sheep grazing and that other livestock will eat the flowers and seed, but that usually the plants don't die unless trampled. Further, it was observed that plants do seem to persist even when grazed. Precipitation and vigor of populations do appear to be tied because in wetter years the species is present in greater numbers with more seedlings; this hasn't been statistically tested, but rather qualitatively assessed. In drought years the species does experience decline and this is due to herbivory from grasshoppers, crickets and livestock. Gophers also cause damage by burying plants, but this damage is usually localized (pers. comm. J. Stenten).
Other recent threats include unauthorized off-road-vehicle use, concentration of livestock due to water sources, and cricket, grasshopper and aphid infestation. Further still, grazing is still an imminent threat as of 2005 (USFWS 2005). Additional information from the Forest Service indicates that more than 100 miles of roads have been closed in Dixie National Forest, however, construction and maintenance of new roads may be a potential threat. Impacts from non-native species have not been observed and probably aren't an issue given the very high elevations at which this species grows (pers. comm. J. Stenten). Further, while roads in the Dixie National Forest are closing, there is still evidence that the species is impacted by road use. In 2004 and 2005, all but three sites visited showed disturbance related to road use. These specific impacts include open or closed roads running through the site, roads adjacent to sites, pack trails next to the sites and some sites with active ATV use (Groebner 2005).