December 2012 Number 1 - Utah Native Plant Society

Utah Native Plant Society
scale saltbush (Atriplex confertifolia), and spiny hopsage
(Grayia spinosa).
Creosote bush-dominated communities tend to persist
in the alluvial fans east of Devil’s Hole and south
along the eastern Refuge boundary in dry uplands and
pavement soils. Approximately 5,000 acres of Creosote
bush Shrubland is found throughout the NE corner of
the refuge. It is dominated by creosote bush (Larrea
tridentata) and white bursage (Ambrosia dumosa) and is
one of the most common vegetation types in the Mojave
Desert (MacMahon 2000).
The central-eastern portions of the Refuge are home
to some of the most extensive old field disturbances and
remnants of agricultural activities conducted prior to the
Refuge’s inception. Many of the non-native old fields
contain Russian knapweed (Acroptilon repens), thistle
spp. (Cirsium spp.) and tamarisk (Tamarix spp.). Old
field non-native vegetation is largely the result of physical
manipulation of land and land cover during agricultural
uses. Old agricultural fields around the dam northeast
of Point of Rocks are largely covered in annual
grasses and forbs but some creosote bush and mesquite
are also recolonizing. The Alkali Seep and transitional
shrubland communities east of the Cold Spring private
property have emerged as an important location for several
endemic species such as Ash Meadows sunray, Ash
Meadows blazingstar, and Ash Meadows ivesia.
Alkali Meadow is a community exclusive to the
Amargosa Valley and Owens Valley ecosystems. The
community is a low-elevation grassland, typically with
moist alkaline soils. Evaporation of surface water often
leaves a crumbled salt crust over the soils. Alkali
Meadow is dominated by inland salt grass (Distichlis
spicata) and alkali sacaton (Sporabolis airoides). Arctic
rush (Juncus arcticus) and whiteflower rabbitbrush are
associated species. The federally listed spring loving
centaury and Ash Meadows ivesia are found in this
community. Alkali meadows are indicative of shallow
water tables. Alkali flats peculiar to Ash Meadows sustain
the highest concentrations of the federally-listed
Amargosa niterwort.
Extensive Alkali Shrubland communities dominated
by Atriplex species (A. lentiformis, A. canescens, and A.
confertifolia) are found in areas where groundwater is
approximately 2-6 meters deep. At AMNWR, Alkali
Shrubland covers 5,000 acres and comprises over 20%
of the area. Alkali Meadow and Alkali Shrubland vegetation
are distributed in close proximity to one another.
In many places, there are raised mounds where the
groundwater may be slightly deeper than surrounding
alkali meadows. In these places, saltgrass, alkali sacaton,
and Atriplex shrub cover increases. Other shrub
species include matchbrush (Gutierrezia sarothrae),
alkali goldenbush, and greasewood (Sarcobatus vermiculatus).
Mesquite bosque vegetation is found pre-
dominantly around spring vents and outflow channels.
The dominant overstory species include mesquite
(Prosopis spp.), Fremont cottonwood (Populus fremontii),
and velvet ash (Fraxinus velutina).
Emergent vegetation is found only at the springs and
along permanent lakes and reservoirs. Emergent vegetation
covers about 130 acres and comprises 0.5% of the
refuge. Common species include Typha spp., spikerush
(Eleocharis) spp., bulrushes, and rush species. Wetlands
associated with the spring complexes include both native
and non-native plant associations.
RARE PLANT SURVEY METHODS
Prior to the establishment of the Refuge, little quantitative
information was available on the life history
strategies, population genetics, demography, community
associations, habitat requirements or abundance of plant
species endemic to Ash Meadows. Implementation of
the recovery plan for the seven listed endemic plant species
will be successful only when these characteristics
are known and disturbed environments are appropriately
managed. Five additional at-risk plant species have been
identified as species of concern at Ash Meadows, bringing
the total to 12 targeted species for rare plant studies
(Tables 1, 2).
Beginning in 2007, BIO-WEST conducted the first
comprehensive inventories of rare, endemic and listed
plant species that occur within Refuge boundaries. The
purpose of the rare plant studies was to obtain a baseline
of existing ecological conditions and rare plant distributions
as a foundation for future monitoring of changes in
the status of rare plant species. The information provided
by these studies will assist with planning future
habitat-restoration activities and can be correlated with
wildlife studies to understand benefits and potential detriments
resulting from these management strategies.
Floristic field surveys were initiated in March 2007
and continued through late October 2008. Survey methods
and intensity depended on the size of the area, investigator
skill, size of the target species, and topography.
Prior to conducting the field surveys, the area was
analyzed to determine potential habitat for each species
of interest. Potential habitat types for each species were
identified in part by literature, background maps provided
by Refuge staff, and observations from field visits
in prior years. An intuitive controlled survey (the most
commonly used and efficient method of surveying for
rare plant abundance), was initially employed in 2007.
The data from these initial surveys were used to design
a more detailed methodology for surveying the distribution
each target species during the 2008 field season.
Surveyors at each population documented the estimated
number of individuals, plant phenology, population distribution
in terms of approximate area, and associated
vegetation. As a general rule plant occurrences less than
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