The Institute for Applied Ecology (IAE) is a 501(c)(3) nonprofit organization with a mission to conserve native species and habitats through restoration, research, and education. Here, we describe some of our projects working with the Conservation Research Program at IAE. The Conservation Research Program conducts research and montioring of native species and ecosystems in order to determine population trends and effective methods for restoration and management, conducts research on invasive species in order to determine effective control methods, and develops plans for the management and restoration of native ecosystems.
Friday, September 7, 2012
Population dynamics of Mulford's milkvetch
Population monitoring at the South Alkali population. Vale, Oregon
Although Oregon is well known for
its coniferous forests, low valley prairies, and coastline that receive high amounts of rainfall, nearly
two thirds of the state exhibits semi-arid habitat conditions. Oregon’s
eastern desert region experiences greater seasonal fluctuation than the western
portion of the state and is inhabited by plants and animals that can tolerate
extreme differences in weather. The high desert receives
significant amounts of snow in the winter, but quickly dries out in the
spring. The characteristic plant
community in eastern Oregon consists of juniper
and sagebrush scrublands with bunchgrasses such as needle-and-thread grass (Hesperostipa comata) and Indian rice grass (Achnatherum hymenoides).
Astragalus mulfordiae (Mulford’s
milkvetch), listed as a Species of Concern by the US Fish and Wildlife Service, is
a member of the legume family (Fabaceae) native to the Snake River Plain of
Oregon and Idaho. In 1995, only 38
populations of Mulford’s milkvetch were known to occur in Oregon,
in addition to 34 populations in Idaho. It was estimated that, in total, there were
less than 12,000 living individuals. Mulford's milkvetch only occurs in desert
shrub communities on sandy substrates, such as lacustrine and alluvial
sediments. The plant relies on
environmental cues to initiate regrowth, but it can generally be seen flowering
between April and June. Flowers are
yellowish to white in color and measure 6-8 mm in length. Fruits usually mature in June and July.
Astragalus mulfordiae
IAE has
tracked Mulford's milkvetch populations in the BLM’s Vale district since 2008,
beginning with the establishment of monitoring plots to determine
the effects of ungulate and rodent grazing on the populations. Large animal exclosures and unfenced control
plots were established at five different sites around Vale, Oregon.
In the second year of monitoring, transects were established
in order to collect data on the plant community associated with
Mulford’s milkvetch. The monitoring
protocol used by IAE is consistent with the methods being used to monitor the
populations in Idaho,
allowing for comparable data sets.
During annual monitoring, data regarding plant life history stage
(reproductive, non-reproductive, seedling) and evidence of herbivory and disturbance were documented,
as well as quantitative data on plant size and number of inflorescences (flowering stems). Population trends were difficult
to discern after the first few years of monitoring, but continued monitoring may
provide more information about the effects of mammal grazing on the size and
health of the Mulford's milkvetch populations. Currently, there
appears to be high turnover of individual plants. The community sampling transects have
revealed ubiquitous invasive and non-native plants that could potentially compete with the native milkvetch. IAE
will continue to monitor these populations to increase understanding of population dynamics for this rare species, and to analyze the potential threats of
cattle grazing, rodent activity, encroachment of invasives, and ground disturbance.
Evidence of cattle activity adjacent to mammal exclosure
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