December 2012 Number 1 - Utah Native Plant Society

Calochortiana December 2012 Number 1
Figure 9. First large-scale reintroduction site for Sentry
milkvetch.
240 seeds sown in the restored parking lot area adjacent
to the Maricopa Point population in July 2011, 51% survive.
Fourteen have set seed on site and produced 58
seedlings. In addition, another 44 milkvetch seedlings
have become established from seed that either washed
in from the adjacent Sentry milkvetch population or
were present in the soil seed bank and germinated. Of
seeds planted in 2011, 15.8% produced seedling plants
that are now alive. In total, there are now 181 sentry
milk-vetch plants growing in this reintroduction site
where habitat beneath a parking lot removed in 2008
was uncovered and restored.
We seeded a second reintroduction area at Maricopa
Point in 2012. Two additional seeding trials were carried
out at the Maricopa Point reintroduction areas in
July 2012 with 518 seeds. We also tested seeding techniques
and watering regimens for this species that will
provide information for continued large-scare reintroduction
efforts.
Finally, we have received a three-year National Park
Service grant to complete installation and establishment
of two new reintroduction plantings. This funding will
continue the momentum of successful reintroduction
efforts. If we can successfully establish these two new
populations and maintain the two large naturally-occurring
sentry milk-vetch populations, Grand Canyon National
Park will be well on its way to downlisting the
species within the next ten years.
Additional References
Busco, J., E. Douglas, and J. Kapp. 2011. Preliminary
pollination study on Sentry milk-vetch (Astragalus
cremnophylax Barneby var. cremnophylax), Grand Canyon
National Park’s only Endangered plant species.
The Plant Press 35(1):11-12.
Falk, M., J. Busco, L. Makarick, and A. Mathis.
2011. The return of the “Watchman of the Gorge.” Endangered
Species Bulletin, Summer 2011. Pp. 40-41.
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