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Amargosa Niterwort (Nitrophila mohavensis)
Amargosa Niterwort
Nitrophila mohavensis
Legal Status
State: Endangered; S1.11
California Rare Plant Rank: 1B.12
Federal: Endangered
Critical Habitat: Originally designated on May 20, 1985 (50 FR
20777–20794)
Recovery Planning: Recovery Plan for the Endangered and
Threatened Species of Ash Meadows, Nevada (Sada 1990)
Notes: N/A
Taxonomy
Amargosa niterwort (Nitrophila mohavensis) is a member of the
Amaranthaceae (Amaranth) family (Wilken 1993). A related species,
Nitrophila occidentalis, can be found in the same general area as
Amargosa niterwort, but N. occidentalis can be easily separated by its
larger size (up to 30 centimeters [12 inches]) and longer linear leaves
(5 to 16 millimeters [0.19 to 0.60 inch]). Current descriptions of these
species’ physical characteristics can be found in the second edition of
the Jepson Manual (Holmgren and Wetherwax 2011).
Distribution
General
This species is restricted to two populations in California and four
populations in Nevada and is endemic to Carson Slough and Ash
Meadows in the Amargosa Desert. It is found only in areas with moist
alkaline soils at elevations of 600 to 750 meters (1,969 to 2,461 feet,
USFWS 2007).
1
2
S1: Critically imperiled; X.1: Very threatened.
1B: Rare, threatened, or endangered in California and elsewhere; X.1: Seriously endangered in California.
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Amargosa Niterwort (Nitrophila mohavensis)
Distribution and Occurrences within the Plan Area
Historical
Two populations of Amargosa niterwort are reported from the Plan
Area (Figure SP-P4; CDFG 2012a). These populations were documented
first by the California Natural Diversity Database (CNDDB) from the
Carson Slough area in 1972 and Tecopa Hot Springs in 1987. Amargosa
niterwort was first collected by Philip Munz and John Roos in 1954 at
the Carson Slough (Munz and Roos 1955).
Recent
According to the U.S. Fish and Wildlife Service (USFWS) 5-year review
for the species, six populations are known: two in California and four
in Nevada, one of which is considered extirpated (USFWS 2007). The
California populations are in the Lower Carson Slough and near
Tecopa Hot Springs. As discussed previously, the CNDDB includes two
occurrences in the Plan Area, both within Inyo County, California. One
occurrence is located in Carson Slough, approximately 2.3 miles
southwest of the California–Nevada border, and the other occurrence
is known from the vicinity of Tecopa Hot Springs, 2 miles north of
Tecopa (CDFG 2012a). The Carson Slough population is found on
lands owned and managed by the Bureau of Land Management (BLM).
The Tecopa Springs population occurs on lands that are privately held
and also on BLM lands.
Natural History
Habitat Requirements
Amargosa niterwort is found in scattered sinks that are fed by
outflows of saline and alkaline springs from Ash Meadows, which
provide constant natural irrigation near the soil surface. It is
restricted to highly alkaline, moist, salt-encrusted clay soils (see Table
1; Sada 1990). No other plants are found in combination with
Amargosa niterwort. However, saltgrass (Distichlis spicata) is
sometimes found on the edges of (or occasionally intermixed with)
populations of Amargosa niterwort (BLM 2006).
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Amargosa Niterwort (Nitrophila mohavensis)
Table 1. Habitat Associations for Amargosa Niterwort
Land Cover Type
Alkaline salt pan
Habitat
Designation
Primary habitat
Habitat Parameters
Salt encrusted clay
soils with natural
subsurface
irrigation.
Supporting
Information
50 FR 20777–
20794; Sada
1990
Reproduction
Amargosa niterwort is an erect, long-lived perennial herb with
extensive underground rootstocks that reproduces both sexually and
asexually. Flowering occurs from May through November (Holmgren
and Wetherwax 2011). Pollinators for Amargosa niterwort are
unknown. Ant species are known to visit Amargosa niterwort for nectar
but they are not presumed to be a likely pollinator (Clark et al. 2010).
Ecological Relationships
It has been noted that this species is sensitive to disturbance and does
not recolonize sites where the salt crust overlying the soil has been
disturbed (Reveal 1978). However, it appears to be resilient to
moderate disturbance, such as road-shoulder maintenance and
disturbance by burrowing animals (SERG 2004). Where the species is
present, it is locally dominant and edaphically restricted and is
considered to be part of the climax assemblage of the Ash Meadows
area (Beatley 1977; Reveal 1978).
Population Status and Trends
Global: G1, Critically Imperiled (NatureServe 2011, Conservation
Status last updated 1998)
State: S1, Critically Imperiled (CDFG 2012b)
Within Plan Area: Same as above
Amargosa niterwort is known from two populations within California
and four populations in Nevada. The largest and most important
population occurs within the Plan Area at the Lower Carson Slough.
This population accounts for approximately 95% of the known
distribution in terms of plant density (USFWS 2007). However, in terms
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Amargosa Niterwort (Nitrophila mohavensis)
of area occupied, the Lower Carson Slough population is the second
largest. In 1985, the USFWS designated 1,200 acres in Ash Meadows
encompassing this population as critical habitat (50 FR 20777–20794).
Demographic sampling in 2003 estimated the Lower Carson Slough
population size at 280,000 ramets (aboveground stems) (USFWS
2007). According to the USFWS 5-year review, the Lower Carson
Slough population is considered to be declining (USFWS 2007). It
appears that the population has not recovered from large-scale farming
operations that occurred during the 1960s and 1970s.
Tecopa Hot Springs is the only other known population of Amargosa
niterwort within the Plan Area. This population was originally
observed in 1963 and is listed as decreasing in size by the CNDDB
(CDFG 2012a). Historical population estimates include two
subpopulations containing approximately 1,000 to 1,500 plants.
However, only an extremely small population was verified at the site
in 2006 (USFWS 2007).
Threats and Environmental Stressors
The biggest threat to Amargosa niterwort is believed to be water
diversion (USFWS 2007). This is largely based on the hydrologic
trends at the Lower Carson Slough population, coupled with the rate
of groundwater extraction within the Amargosa Valley. Other threats
to this species include road construction projects, mineral mining,
trampling by wild horses, and habitat destruction by off-highway
vehicles (OHVs) (CNPS 2011; USFWS 2007).
Conservation and Management Activities
In the Plan Area, Amargosa niterwort occurs primarily on lands
managed by the BLM and is addressed in the “Amargosa River Area of
Critical Environmental Concern Implementation Plan” (BLM 2006).
Active management on BLM lands within the Plan Area for this
species has included installing fencing along Ash Meadows Road to
protect the Lower Carson Slough population from OHV activity. In
consultation and coordination with Ash Meadows National Wildlife
Refuge, recovery and research actions include: establishment of new
Amargosa niterwort populations in unoccupied, suitable habitat,
based on monitoring results and literature review and monitoring to
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Amargosa Niterwort (Nitrophila mohavensis)
better determine specific habitat requirements for Amargosa
niterwort. In addition, the wild horse population is limited in size and
the wild burrow population was eliminated (BLM 2006).
In addition, occurrences in the Ash Meadows National Wildlife Refuge
in Nevada are managed by the USFWS, including protection from
OHVs and surface mining where the USFWS owns mineral rights and
preparation of an Integrated Pest Management Plan (USFWS 2007).
Data Characterization
The general distribution of Amargosa niterwort is well known based on
its primary association with the surface expression of deep carbonate
aquifers. Within the Plan Area, this species is known from Carson
Slough and near Tecopa Springs, both within Inyo County. Little is
known regarding the species’ pollination, but the species is known to
reproduce both sexually and asexually. Although data are anecdotal, the
largest population at Lower Carson Slough and the small population at
Tecopa Hot Springs appear to be declining (USFWS 2007).
Management and Monitoring Considerations
Management primarily involves ensuring adequate groundwater and
high-salt-content soils to maintain suitable habitat for Amargosa
niterwort. Control of invasive species such as tamarisk, which create
fire hazards and compete for water, is also an important
management consideration.
The USFWS (2007) recommended several actions in the 5-year review
for the species, including monitoring population trends for this
species in relation to groundwater pumping using scientifically
rigorous methods; additional research into the hydrology of the
Central and Lower Carson Slough as it relates to the Ash Meadows and
Alkali Flat/Furnace Creek hydrologic subbasins, including additional
groundwater monitoring wells; modifications to Ash Meadows Road
to limit potential impacts of flash flood or failure of Crystal Spring
Dam to the Lower Carson Slough population; and repair, modification,
or removal of Crystal Spring Dam. The BLM also identified monitoring
to better understand habitat requirements and establishment of new
populations in unoccupied, suitable habitat (BLM 2006).
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Amargosa Niterwort (Nitrophila mohavensis)
Predicted Species Distribution in Plan Area
There are approximately 12,272 acres of modeled suitable habitat
for Amargosa niterwort in the Plan Area. Suitable habitat is modeled
on clay soils and weathered bedrock near seeps/springs and playas,
from 1,800 to 2,500 feet. The entire model is restricted to the area
within 10 miles of the Amargosa River in the Amargosa DesertPahrump Valley and Funeral Mountains-Greenwater Valley
ecoregion subsections. Appendix C includes specific model
parameters and a figure showing the modeled suitable habitat in the
Plan Area.
Literature Cited
50 FR 20777–20794. Final Rule: “Endangered and Threatened
Wildlife and Plants; Determination of Threatened Status with
Critical Habitat for Six plants and One insect in Ash Meadows,
Nevada and California; and Endangered Status with critical
habitat for One Plant in Ash Meadows, Nevada and California.”
May 20, 1985.
Beatley, J.C. 1977. “Ash Meadows: Nevada’s unique oasis in the Mojave
desert.” Mentzelia 3: 20–24.
BLM (Bureau of Land Management). 2006. Amargosa River Area of
Critical Environmental Concern Implementation Plan. Barstow,
California: BLM Field Office.
CDFG (California Department of Fish and Game). 2012a. “Nitrophila
mohavensis.” Element Occurrence Query. California Natural
Diversity Database (CNDDB). RareFind, Version 4.0
(Commercial Subscription). Sacramento, California: CDFG,
Biogeographic Data Branch. Accessed February 2012.
CDFG. 2012b. Special Vascular Plants, Bryophytes, and Lichens List.
California Natural Diversity Database (CNDDB). January 2012.
Accessed March 2012. http://www.dfg.ca.gov/biogeodata/
cnddb/plants_and_animals.asp.
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Amargosa Niterwort (Nitrophila mohavensis)
Clark, M.C., D.A. Tanner, and J.P. Pitts. 2010. “Insect Visitors and
Possible Pollinators of AMNWR Plants of Concern.” Accessed
online June 29, 2011. http://www.fws.gov/desertcomplex/
ashmeadows/docs/2010_symposium/11_C_Clark_Insect_Visito
rs_FINAL2.pdf.
CNPS (California Native Plant Society). 2011. “Amargosa Niterwort
(Nitrophila mohavensis).” Inventory of Rare and Endangered
Plants (online edition, v8-01a). Sacramento, California:
California Native Plant Society. Accessed May 12, 2011.
http://www.cnps.org/inventory.
Holmgren N.H. and M. Wetherwax. 2011 (in press). “Nitrophila.” In
The Jepson Manual: Vascular Plants of California, Second
Edition, edited by B.G. Baldwin et al. Berkeley, California:
University of California Press. Accessed June 29, 2011.
http://ucjeps.berkeley.edu/tjm2/review/treatments/
amaranthaceae.html#11503
Munz, P.A. and J.C. Roos. 1955. “California miscellany III.” Aliso 3:
111–119.
NatureServe. 2010. “Nitrophila mohavensis.” NatureServe Explorer: An
Online Encyclopedia of Life [web application]. Version 7.1.
Arlington, Virginia: NatureServe. Accessed March 26, 2012.
http://www.natureserve.org/explorer.
Reveal J.L. 1978. Status Report on Nitrophila Mohavensis. Portland,
Oregon: U. S. Fish and Wildlife Service.
Sada D.W. 1990. Recovery Plan for the Endangered and Threatened
Species of Ash Meadows, Nevada. Prepared for the U.S. Fish and
Wildlife Service (Portland, Oregon). Reno, Nevada: U. S. Fish
and Wildlife Service.
SERG (Soil Ecology and Research Group). 2004. “Demographics and
Ecology of the Amargosa Niterwort (Nitrophila mohavensis)
and Ash Meadows Gumplant (Grendelia fraxino-pratensis) of
the Carson Slough Area.” Last update February 27, 2004.
Accessed online June 30, 2011.: http://www.sci.sdsu.edu/
SERG/restorationproj/mojave%20desert/deathvalleyfinal.htm.
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Amargosa Niterwort (Nitrophila mohavensis)
USFWS (U.S. Fish and Wildlife Service). 2007. Amargosa Niterwort
(Nitrophila mohavensis) Five-Year Review: Summary and
Evaluation. Las Vegas, Nevada: USFWS, Nevada Fish and
Wildlife Office. December 2007.
Wilken, D.H. 1993. “Nitrophila.” In The Jepson Manual: Higher Plants of
California, edited by J.C. Hickman, p. 512. Third printing, with
corrections. Berkeley, California: University of California Press.
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