December 2012 Number 1 - Utah Native Plant Society

Calochortiana December 2012 Number 1
Washington County, Red Cliffs Desert Reserve, the
Shivwits Band of the Paiute Tribe, Zion National Park,
Utah Native Plant Society, Utah Natural Heritage Program,
School and Institutional Trust Lands Administration,
The Nature Conservancy, and more.
Spatial Landscape Modeling: The Land Manager’s
Tool Box
Elaine York and Louis Provencher, The Nature Conservancy,
Salt Lake City, UT.
Abstract: Facilitated by The Nature Conservancy, the
Spatial Landscape Modeling Project quantitatively modeled
the reference and current conditions for seventeen
major vegetation types in the Grouse Creek Mountains
and Raft River Mountains, a 1.1 million acre landscape
in northwest Utah. Partners – including Utah Partners
for Conservation and Development, Bureau of Land
Management, Sawtooth National Forest, Utah Division
of Wildlife Resources, National Resources Conservation
Service, Quality Resource Management, and private
landowners – shared management data to explore effectiveness
of current management and developed computer-generated
alternative management scenarios to
consider options for optimal land health. Cutting-edge
technology from remote sensing, GIS analysis and partner-informed
computer models produced a number of
tools to assist land managers in their understanding of
large-scale vegetation dynamics, long-term management
options and the importance of management cooperation
across land-ownership borders.
An Update on Ecological Investigations of the
Shivwits Milk-Vetch (Astragalus ampullarioides),
Washington County, Utah
Mark E. Miller and Rebecca K. Mann, formerly US
Geological Survey, Southwest Biological Science Center,
Kanab, UT; Rebecca Lieberg, Cheryl Decker and,
Kathy Davidson, Zion National Park, and Harland Goldstein
and James D. Yount, U.S. Geological Survey,
Earth Surface Processes Team, Denver, CO
Abstract: The Shivwits milk-vetch (Astragalus ampullarioides)
is one of four federally protected plant species
restricted to particular geologic substrates at the edge of
the Colorado Plateau and Mojave Desert in Washington
County, Utah. Since 2006, the U.S. Geological Survey
and National Park Service (Zion National Park, ZNP)
have been studying this species in relation to geology
and soils, herbivory, exotic plants, and mycorrhizal
fungi. Habitat studies in 2006 documented the species
on a new geologic substrate and across a broad range of
soils, expanding the concept of potential habitat. Consumption
of inflorescences by native herbivores reduced
reproductive output in a ZNP subpopulation by 90% in
2006 (low production year) and 75% in 2008 (high production
year). Preliminary analyses indicate no significant
effects of exotic red brome (Bromus rubens) biomass
on growth or reproductive output of established
milk-vetch plants in the same subpopulation during
spring 2008. Effects of brome biomass on seedling recruitment
remain unclear because low precipitation in
2006 and 2007 prevented seed collection required for
experimental studies. In 2007, median soil seed bank
density in plots at ZNP was 45.7 seeds m 2 , with an extremely
high density (2741 seeds m 2 ) in the plot with the
sandiest soil. Coarse textured soils in this plot may reduce
germination frequency, thereby resulting in longterm
seed accumulation. Overall, results to date indicate
that caging to exclude native herbivores may be the least
expensive way to improve the viability of extant populations
by enhancing reproductive output.
Population Genetic Structure of an Endangered
Utah Endemic Astragalus ampullarioides (Welsh)
Welsh (Fabaceae)
Jesse W. Breinholt, Utah Valley University, Orem, UT
and Brigham Young University, Provo, UT; and Renee
Van Buren, Olga R. Kopp, and Catherine L. Stephen,
Utah Valley University, Orem, UT
Abstract: The Shivwits milkvetch, Astragalus ampullarioides
(Welsh) Welsh, is a perennial herbaceous plant
in the family Fabaceae. This Utah edaphic endemic was
federally listed as Endangered in 2001 because of high
habitat specificity and low numbers of individuals and
populations. All known occupied habitat for A. ampullarioides
was designated as critical habitat by the US
Fish and Wildlife Service in 2006. We used AFLP
markers to assess genetic differentiation among the
seven extant populations and quantify genetic diversity
in each. Six different AFLP markers resulted in 217 unambiguous
polymorphic loci. We used multiple methods
to examine how population genetic structure in this species
has changed over time. The genetic data indicate
that, relatively recently, A. ampullarioides consisted of a
single large contiguous genetic unit that fragmented
over time into 3 genetic regions. These regions further
fragmented and extant populations have differentiated
through genetic drift. Populations exhibit low levels of
gene flow, even between geographically close populations.
We suggest plans for population establishment or
augmentation carefully consider the genetic makeup of
each of the extant populations.
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