Pediocactus paradinei

Pediocactus paradinei is a perennial cactus that is endemic to northern Arizona on eastern slopes of the Kaibab Plateau and adjoining areas in Coconino County. It is found in gravely Kaibab limestone soils in transitional areas between woodland and sagebrush communities. Pediocactus paradinei is known from 27 occurrences, many of which have not been resurveyed in the past 30 years. It is threatened by high intensity fire, woodland canopy closure due to fire suppression, illegal collection, road construction, livestock grazing, predation by rodents, and drought. The majority of this species' range occurs on U.S. Forest Service lands where there is a Conservation Area established to help protect Pediocactus paradinei. Within the Conservation Area, grazing activities are limited to when cacti are not in flower, the area is closed to off-road travel, and proposed development projects must be evaluated for impacts to cacti. While population size and trends remain uncertain, monitoring efforts continue.

Pediocactus paradenei occurs in western North America, where it is endemic to northern Arizona in Coconino County, USA (Benson 1982). Specifically, this cacti occurs exclusively on the eastern slopes of the Kaibab Plateau and small portions of adjoining House Rock and Coyote valleys (USFWS 2015). The species' historic range included Mohave County (Benson 1982), but no specimens have been relocated west of the Coconino County line (USFWS 2015). Range extent was estimated to be 177 square km using Arizona Natural Heritage Program occurrences and herbarium specimens collected between 1987 and 2014 (SEINet 2024, AZNHP 2025).

The Arizona Natural Heritage Program currently tracks 27 occurrences for this species (NatureServe 2024). However, twenty of these have not been surveyed in the past 30 years.

Pediocactus paradinei is primarily threatened by both fire (there is high mortality when cacti are exposed to high intensity fires), and fire suppression from woody shrub encroachment into its open grassland habitat (AGFD 2020). Cactus mortality following high intensity fires has been documented. For example, an August 1990 prescribed fire killed 46 cacti in a monitoring plot (NatureServe 2024). Several high intensity wildfires occurring on the Kaibab Plateau (notably Warm Fire and Pasture Canyon) have impacted Pediocactus paradinei individuals, and have also led to changes in the composition and density of vegetation and soil loss in suitable habitat for the species. This species is also vulnerable to poaching by collectors, and in 1989, thirteen cacti were taken from a monitoring plot. However, the current severity of this threat is unknown. Trampling by livestock, heavy rodent predation, road construction, and drought and climate change are all additional threats to this species (AGFD 2020, AZNHP 2012, USFWS 2015). Drought coupled with rodent herbivory likely extirpated Pediocactus paradinei located on Bureau of Land Management lands at lower elevations, and four cacti were eaten by rodents in 2005 (USFWS 2015). Being found on fairly open, level sites increases the plants' vulnerability to impacts from recreation, such as camping, and from road construction. Noxious weeds, pollinator decline, and root rot during very wet years may also contribute to population decline (AZGFD 2020).