In Flora of North America, Volume 4 (2003), Echinocereus fendleri is treated as a highly variable species without recognition of subspecific taxa. The New Mexico Rare Plant Technical Council (NMRPTC) does not accept this treatment and will continue to consider E. fendleri var. kuenzleri to be a distinct entity. In discussions at the 2005 NMRPTC Meeting, Council members concluded that E. fendleri var. kuenzleri represents a population of plants that is geographically defined and sufficiently distinct from other closely related populations that it deserves taxonomic recognition (NMRPTC, 1999).
Geographic Information Systems (GIS) technology which provides mapping layers for geology, soils, vegetation, and elevation, has been useful for identifying focus areas of potential habitats for field surveys (Chauvin et al. 2001). This has led to the identification of additional populations, and provided a basis for gross estimates of populations in unsurveyed areas (USFWS, 2005).
Studies conducted by the Natural Heritage Program at the University of New Mexico have found greenhouse grown E. f. var. kuenzleri seed to produce E. f. var. kuenzleri plants (Tonne, conversation, September 2004). This suggests that traits are stable and heritable from a unique genotype, yet it does not rule out the plants ability to express a variation of phenotypes on the periphery of its range (USFWS, 2005).
A two-year study (1984-1985) by The Nature Conservancy found that during a year of cattle grazing with 65% forage utilization, cactus mortality outside a fenced exclosure was 12.4% while there was zero mortality inside the exclosure where no grazing had occurred (Bates 1985). Intensive livestock grazing can cause some mortality by trampling individual cacti. However, the indirect impacts of livestock grazing may be more significant for increased erosion and removal of insulating cover that may affect the success of seedling establishment (USFWS, 2005).
Commercial growers have significantly contributed to the conservation of Kuenzlers hedgehog cactus by offering greenhouse-grown plants and seeds to hobbyists who might otherwise obtain their plants or seeds from natural populations (USFWS, 2005).
Research on the impacts of fire has been initiated by USDI-BLM to determine which fire variables (e.g. intensity and seasonality) has the least effect on Kuenzlers hedgehog cactus. Kuenzlers hedgehog cactus individuals involved in the study are located in Lincoln and Eddy counties, and are associated with the Fort Stanton and South Texas Hill populations, respectively (USDIBLM, CFO 2003). The results of this study are not yet available (USFWS, 2005).
In an effort to better circumscribe the infraspecific taxa of Echinocereus fendleri, Baker (2007) undertook a study using multivariate statistics to compare the degree of morphological variation within and between populations. He concluded that Echinocereus fendleri consists of three morphologically and geographically distinct races that when recognized at the varietal level should be named E. fendleri var. fendleri, E. fendleri var. kuenzleri, and E. fendleri var. rectispinus (Baker, 2007).