USFWS Grant for Enhancing Cultivation Protocols for Applegate’s Milkvetch Recovery

Applegate’s milk-vetch (Astragalus applegatei) is one of Oregon’s rarest and most endangered plant species. Only a few sites remain, all confined to a very local area within or near Klamath Falls, Oregon. All but one of these appear to be declining due to significant habitat deterioration or fragmentation. The establishment of new (or augmented) populations, through the transplanting of individuals cultivated off-site, may be an important tool for maintaining the numbers and distribution of the species. Previous research on the topic has established favorable protocols for A. applegatei seed collection and germination, identified important basic edaphic requirements necessary for its ex situ cultivation (i.e., mycorrhizal/bacterial), and explored methods for selecting potential transplant sites and outplanting cultivated individuals.

The federal Recovery Plan for A. applegatei calls for increasing our knowledge of cultivation and outplanting techniques (Task 3.2) as well as the establishment of wild population reserves (Task 1.54), to promote the long-term survival of the species. Earlier field efforts have resulted in stores of viable seed, taken from the smaller extant A. applegatei populations on non-federal land. These were previously used in growing young plants for potential outplanting at suitable sites in the Klamath Falls area. In the 1990’s many of these plants died after outplanting attempts (plants used were typically <1 year old), and others (in a recent cultivation project) succumbed to fungal disease in the greenhouse. Additional seeds will be collected under this proposal in 2008, in consultation with USFWS (focusing on the two largest known and recently discovered sites for the species), and tested for viability and germinability. These seeds will then be used to grow a new round of greenhouse starts in soils inoculated with native mycorrhizae, and under a lowered humidity regime that should minimize disease-related mortality. The goal will be to grow and maintain containerized plants for future outplanting at one or more appropriate sites in the Klamath Basin (in consultation with USFWS). In past outplanting projects, the use of younger plants (i.e., those in their first year, usually 6-8 months old) was correlated with high mortality, even though transplants were reproductive and believed large enough (1-2 dm across minimum) to survive. Ensuing discussions with USFWS have since established a preference among project participants for keeping plants in cultivation for a minimum of two years before outplanting, to increase root/shoot biomass ratios and enhance mycorrhizal inoculation, thereby increasing the likelihood of survival and reducing transplant shock. The introduction of experimental populations of A. applegatei, via the outplanting of individuals cultivated ex situ, is considered vital to its recovery. To date this has been a challenging undertaking for this taxon. The work proposed here would make use of previously collected seed as well as seed to be gathered in 2008, to hopefully develop a stock of greenhouse-grown individuals for the potential establishment of one or more reserve populations within the natural range of the species, as called for in the Recovery Plan. Ideally, plants will be grown for at least 2 years before outplanting. Timeline Spring and summer 2008 Initial project consultations Early summer through fall 2008 Field assessments; seed and soil inoculant collections June—December, 2008 Seed scarification and germination; seedling potting; general cultivation work December 31, 2008 written summary provided to USFWS