December 2012 Number 1 - Utah Native Plant Society

Utah Native Plant Society
Table 1. Statistical Summary of the Flora
of Cedar Breaks National Monument*
Category
Taxonomic Diversity
Species &
Varieties
Full Species
Only
No. of Taxa
Confirmed
Present
No. of Taxa
Reported
(not confirmed)
Total
347 7 354
335 5 340
Families 56 0 56
Biogeographic Diversity
Introduced 17 1 18
Native 330 6 336
Locally
Endemic
Regionally
Endemic
18 0 18
20 0 20
Disjunct 2 0 2
Peripheral 0 0 0
Sparse 6 0 6
Widespread 284 6 290
The number of taxa and plant families is based on Welsh and
others (2008). Biogeographic diversity categories refer to the
distribution of a species within Utah and the state’s contribution
to its overall global range (Fertig 2009b). Introduced taxa
are not native to Utah or North America but have become
naturalized (breeding on their own without human assistance).
Local Endemics have their entire global range restricted
to an area of less than 16,500 square km (ca 6370 sq
miles, or 1 degree of latitude x 2 degrees of longitude). Regional
Endemics have global ranges of 16,500-250,000
square km (an area about the size of Wyoming). Disjuncts are
isolated from the contiguous portion of their range by a gap
of more than 800 km (ca 500 miles). Peripherals are widespread
globally but occur at the margin of their contiguous
range in Utah and occupy less than 5% of the state’s area
(usually only within a few miles of the state border). Sparse
taxa occur widely across Utah or North America but their
range within Utah is small and patchy, with populations restricted
to specialized or uncommon habitats. Widespread
taxa have global ranges exceeding 250,000 square km and
occur over at least 10% of the state.
* See Addendum for additional species documented since
2009.
Breaks National Monument are presently listed as sensitive
by the US Forest Service or BLM and 14 were once
candidates for listing as Threatened or Endangered under
the US Endangered Species Act (Table 2).
During 2007-2008 we targeted 16 of Cedar Breaks’
rarest local endemics and CDC species of concern
(Table 2) for survey. The number of target species increased
to 18 with the discovery of extant populations of
Madsen’s daisy and the first records of Welsh’s aster
(Aster welshii) for the monument. We recorded at least
one population of 16 of the target species at 546 different
sampling points within Cedar Breaks National
Monument or the Ashdown Gorge Wilderness Area.
Since more than one target species was often present at
each location, we actually documented 1181 different
sample points for these species. For the clonal species
Salix arizonica we delineated 16 discrete polygons in
three main population clusters that cover a total area of
just over one hectare (Fertig and Reynolds 2009).
Ten of our target species occurred in over 10% of our
samples. These species were found mostly on the red or
white limey-sandstone layers of the Claron Formation
along the rim and slopes of the Cedar Breaks Amphitheater.
Cedar Breaks wild buckwheat (Eriogonum panguicense
var. alpestre) was the most widespread and
abundant of the rare species, being found in 36% of all
samples and having a population estimated at 35,200-
100,000 individuals (Fertig and Reynolds 2009). This
plant also has the smallest geographic range of any
taxon in our study, being known only from the Cedar
Breaks area within the monument and the adjacent
Dixie National Forest and Ashdown Gorge Wilderness.
Only three other species were estimated to have populations
of over 10,000 plants: Least lomatium (Lomatium
minimum), Markagunt aster (Aster wasatchensis var.
wasatchensis), and Least spring-parsley (Cymopterus
minimus). The least abundant and most restricted species
in the study area were Rosy cliff jamesia (known
from only about 100 plants in two main areas; Madsen’s
daisy (approximately 400 plants in three main areas),
Reveal’s paintbrush (Castilleja parvula var. revealii
with 500 plants in two main populations), Podunk
groundsel (Senecio malmstenii with about 1500 individuals
in five sites), and Welsh’s aster (with an estimated
1700 plants scattered along Ashdown and Rattle
creeks in the bottom of the amphitheater).
We were unsuccessful in relocating just one of the 18
target species, the Zion draba (Draba asprella var. zionensis).
This species is known from a single herbarium
specimen (Dickman s.n. CEBR) collected from “Cedar
Breaks National Monument” in 1977. Unfortunately,
nothing more precise is known about the original collection
site. Zion draba occurs commonly in Zion National
Park on Navajo Sandstone cliffs and canyons. Comparable
Navajo Sandstone outcrops are not exposed at Cedar
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