December 2012 Number 1 - Utah Native Plant Society

Calochortiana December 2012 Number 1
Mexico. The dramatic and almost complete demise of
aridland ciénegas from aquifer depletion in the Chihuahuan
Desert of Texas left only two populations of Pecos
sunflower in a region that probably contained several.
Some of the New Mexico populations are also damaged
or threatened by aquifer depletion and nearly all are degraded
by exotic tree infestations (USDI-Fish & Wildlife
2008). Pecos sunflower was listed as a federally
threatened species in 1999 and its ciénega habitats are
finally receiving some management attention specific to
the needs of this plant.
Wright’s marsh thistle (Cirsium wrightii A. Gray)
sometimes occurs in the same New Mexican ciénegas
occupied by Pecos sunflower, but there appear to be
fewer thistle populations in the United States. It ranges
from southeastern New Mexico to southeastern Arizona
and northern Chihuahua and Sonora. The type locality
and single Arizona location at San Bernardino Ciénega
has not been seen again since that ciénega was dried by
down-cutting of the adjacent Black Draw. Some New
Mexico populations at Lake Valley, Sacramento Mountain
springs, and the City of Roswell (Country Club)
have also been extirpated (New Mexico Rare Plant
Technical Council 1999, Sivinski 1995, 2005). This is
clearly a threatened ciénega species in the United States;
however, the status of this plant in México is unknown.
A dismal trend of aridland spring loss in México (Contreras
and Lozano 2002, Unmack and Minckley 2008)
offers little hope that this species is faring better south
of the border. Cirsium mohavense (Greene) Petrak
(synonym = Cirsium virginense Welsh) is a related wetland
thistle that may be occupying the same sinking ship
in the Mojave Desert except that the Mojave thistle is
not exclusively a ciénega plant and also occurs in some
hanging garden and riparian habitats (Utah Native Plant
Society 2008).
Leoncita false foxglove (Agalinus calycina Pennell)
also co-occurs with Pecos sunflower and Wright’s
marsh thistle in a ciénega at Bitter Lake National Wildlife
Refuge in southeastern New Mexico. It is otherwise
only known from an extant population at the Diamond
Y Spring ciénega in western Texas, another historic and
ambiguous collection in western Texas, and an historic
collection in Coahuila (Poole et al. 2007). This is another
species with almost no data available on its status
in México. It seems to be exceedingly rare, but much
additional research must be accomplished to support the
initial appearance of rarity.
Additional botanical surveys of all ciénegas in the
southwestern United States and northern México will be
needed to fully understand ciénega plant distributions
and the threats to their habitats. Botanists should consult
southwestern ichthyologists, herpetologists and aquatic
invertebrate biologists who have been much more ag-
gressive in locating and gaining access to aridland
springs. They can help determine which springs support
ciénega habitats and may already know many of the
landowners.
MANAGEMENT CHALLENGES
Some remnant southwestern ciénegas have been acquired
by federal and state governments and The Nature
Conservancy as natural preserves or wildlife refuges.
These have usually been protected because of the rare or
endangered animals inhabiting the actual spring features,
but the rare ciénega plants also need to be considered
in preserve management. Ciénegas are productive
and dynamic biotic communities that have attracted use
by large herbivores for millions of years. A protective
fence and hands-off approach for preserve management
may only yield a ciénega that is overgrown, thatchy,
drying, and pest-ridden (Kodric-Brown and Brown
2007, Unmack and Minckley 2008). Needs for grazing
or fire prescriptions, aquifer protection or restoration,
and weed control calls for active management.
Restoration and management of ciénegas affected by
arroyo cuts that have lowered the potentiometric surface
of adjacent springs and seeps will require the very difficult
task of aggrading incised channels (Minckley and
Brunelle 2007, Turner and Fonseca 2008). The ground
water of a dead or damaged ciénega may still be close to
the surface, but requires significant sedimentation and
restoration of sheet flow to bring the potentiometric surface
back to ground level and re-establish a “living” ciénega.
On the other hand, former ciénegas supported by
spring aquifers that have been depleted by groundwater
pumping are unlikely to resume surface flow and become
“living” again for the foreseeable future.
Blue Hole Ciénega in Santa Rosa, New Mexico was
purchased by the State Forestry Division’s Endangered
Plant Program in 2005 to preserve critical habitat for the
endangered Pecos sunflower and Wright’s marsh thistle.
This 116-acre ciénega was about one-third infested with
Russian olive trees (plus salt cedar to a lesser extent),
suddenly ungrazed by livestock, and illustrative of some
vegetation management challenges in a ciénega preserve
(Figures 3 and 4).
Weed tree control was an immediate concern because
the entire ciénega was rapidly trending towards Russian
olive woodland. Inmate work crews with chainsaws and
backpack herbicide sprayers spent a total of 3,600 manhours
cutting trees, spraying stumps, and broadcasting
slash during the late summer and autumn months when
the soil surface was dry over much of the ciénega. Winter
to summer was an unsuitable period for weed control
because effective herbicides could not be used while the
soil surface was constantly wet or pooling water. The
initial percent kill for tree stumps was about 80%.
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