December 2012 Number 1 - Utah Native Plant Society

Utah Native Plant Society
matic increases in the number of reproductively mature
individuals on the south-facing slopes of cinder cones in
the vicinity of Sunset Crater and Indian Flat (J.D.
Springer, personal observations, 2008 and 2009).
Although some P. clutei populations contain hundreds
or thousands of individuals, populations are often
widely dispersed, and there are a few major threats that
could jeopardize this species in the future. The entire
range of P. clutei has not yet been mapped; however, a
large portion of its known range falls within the Cinder
Hills OHV (off-highway vehicle) area (Figure 1). Most
of this area is not fenced and OHV use spills outside the
boundaries shown in the map. Although P. clutei appears
to benefit from disturbance, whether disturbance
is beneficial or detrimental depends on the type of disturbance
and the amount of impact. No quantifiable data
has yet been collected on the impacts of OHV activity
on this species, but anecdotal evidence points to OHVs
as a direct factor in adult P. clutei mortality (J.D.
Springer, personal observations, 2008). OHV activity
causes above- and belowground soil impacts, resulting
in decreased soil moisture, increased soil bulk density,
and increased water infiltration time, which have been
shown to negatively impact plant species in the area,
such as ponderosa pine (Kennedy 2005).
While OHV use and impacts can be controlled, potential
negative changes to P. clutei habitat from climate
change cannot. Climate models predict a more arid climate
in the southwestern U.S. in the coming decades
(Seager et al. 2007). This species already lives in a
harsh environment, and any major decreases in available
soil moisture could significantly impact its long-term
viability. Additional threats include potential hybridization
with other Penstemon species brought to the area
for horticulture or highway revegetation purposes, herbivory,
insect damage and urban expansion.
Determining the long-term population dynamics of
this species is integral to future conservation management
planning and points out the direct need for longterm
monitoring, particularly in the face of potential
climate change and unmanaged OHV use in the center
of its habitat. Teasing out whether P. clutei population
declines occur from disturbance, absence of disturbance,
senescence, competition, drought, climate change, interactive
effects, or other as yet undetermined factors will
be critical for understanding future conservation and
management needs for this species.
ACKNOWLDEGMENTS
We thank Deb Crisp, Barb Phillips, and Frank Thomas
(Coconino National Forest), Steve Rosenstock
(Arizona Game and Fish Department), Paul Whitefield
(National Park Service), and Susie Smith (Northern Arizona
University) for their assistance in gathering locations
and for their input on ecology and experimental
design; Scott Abella (UNLV and Public Lands Institute)
and Nancy Brian (National Park Service) for their review
of the manuscript; and Joe Crouse, Mark Daniels,
Chris McGlone, Mike Stoddard, Chelsea Green, Cat
McGowan, Don Normandin and students and staff of
the Ecological Restoration Institute at Northern Arizona
University for assistance with data collection, mapping,
greenhouse study maintenance and statistical analysis.
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