Field Assessment of Sensitive Plant Occurrences at Craters of the Moon National Monument and Preserve

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Craters of the Moon National Monument and Preserve (‘the Monument’) lies along the Great Rift Zone of central Idaho on the northern edge of the Snake River Plain. It encompasses 111,393 ha (275,260 ac) managed by Bureau of Land Management (BLM), and 187,539 ha (463,420 ac) managed by the National Park Service. Within the Monument bounds, about 3300 ha (8000 ac) are managed by Idaho Department of Lands, and about 2600 ha (6400 ac) are private. The Monument is best known for its volcanic features, but it also harbors a substantial diversity of native plants, including several sensitive species. With funding from BLM, we targeted 15 sensitive or potentially sensitive taxa that were suspected or known to occur in the Monument. We compiled location data from herbarium records, our own database of rare plant occurrences, and the ‘Checklist of Vascular Plants—Craters of the Moon National Monument and Preserve (CRMO) Arco, Idaho, USA’ (Popovich 2006). We also examined records within a buffer of approximately 8 km (5 mi) around the Monument. We conducted field assessments of the sensitive plant occurrences from Spring 2016 through Summer 2018. Our fieldwork occurred primarily from early-May to mid-July, and focused on each targeted species when it was in flower or fruit. In the field, we used a handheld Garmin GPS unit to record search routes and waypoints of targeted plants. For each individual or cluster of plants, we collected data on population size, site characteristics, associated species, and disturbances. Here, we present the results of our field assessments. We present general information on each species in a separate guide (Miller and Kinter 2020). <br>

We determined that five of the sensitive taxa reported from the Monument prior to our study were misidentified: Allium aaseae and/or Allium anceps, Asclepias subverticillata, Coryphantha sp., Downingia bacigalupii, and Penstemon montanus var. idahoensis. Their correct identifications are Allium sp. nov. (a single new species), Asclepias fascicularis (a milkweed of interest, but not a sensitive species), Pediocactus simpsonii (a sensitive species), Porterella carnosula (a sensitive species), and Penstemon montanus var. montanus (not sensitive), respectively. At 16 of the 29 locations we assessed, we found the targeted species: Antennaria arcuata (1), Asclepias fascicularis (1), Astragalus atratus var. inseptus (3), Astragalus oniciformis (7), Eriogonum ovalifolium var. focarium (2), Primula cusickiana var. cusickiana (1), and Pyrrocoma insecticruris (1). We also documented a new population of Eriogonum ovalifolium var. focarium located north and south of Highway 20/26/93 near milepost 229. Astragalus oniciformis, Eriogonum ovalifolium var. focarium, and Primula cusickiana var. cusickiana were observed within the Monument boundary; Antennaria arcuata, Asclepias fascicularis, and Astragalus atratus var. inseptus were outside the boundary but within the buffer; Pyrrocoma insecticruris was outside the boundary and buffer, but we believe it could occur within the Monument. Although our research did not emphasize surveying for new populations, we occasionally surveyed when we encountered habitat that seemed particularly promising, e.g., potential habitat for Phacelia inconspicua at the southeast end of Snowdrift Crater, and potential habitat for Allium sp. nov. and Eriogonum ovalifolium var. focarium at Ant Butte. We did not find any new populations of these or other sensitive species on BLM land.

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Reference Code: U20KIN01IDUS <br>

Full Citation: Kinter, C.L., and J.J. Miller. 2020. Field Assessment of Sensitive Plant Occurrences at Craters of the Moon National Monument and Preserve. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise. 46 pp. plus appendices. <br>

Location: ELECTRONIC FILE - BOTANY: MULTIPLE SPECIES <br>

Keywords: Craters of the Moon National Monument and Preserve, Snake River Plain, Element Occurrence, habitat, Idaho, rare plant conservation, sensitive species, Idaho native plants, Allium, onion, Antennaria arcuata, arching pussytoes, Asclepias fascicularis, narrowleaf milkweed, Astragalus atratus var. inseptus, mourning milkvetch, Astragalus oniciformis, Picabo milkvetch, Eriogonum ovalifolium var. focarium, Craters of the Moon cushion buckwheat, Pediocactus simpsonii, Simpson’s hedgehog cactus, Phacelia inconspicua, obscure phacelia, Porterella carnosula, western porterella, Primula brodheadae, Brodhead’s primrose, Primula cusickiana, Cusick’s primrose, Pyrrocoma insecticruris, bugleg goldenweed <br>