Surveying and Occurrence Assessments for Agastache cusickii (Cusick's giant-hyssop) and Agoseris lackschewitzii (pink agoseris) on the Caribou-Targhee National Forest

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Agastache cusickii (Cusick's giant-hyssop, Lamiaceae) and Agoseris lackschewitzii (pink agoseris, Asteraceae) are known from the Caribou-Targhee National Forest. Prior to our 2013 fieldwork, some of the occurrences had not been visited in many years, while others had never been formally documented using the Idaho Natural Heritage Program methodology. In the spring of 2013, we found six Element Occurrence (EO) records of A. lackschewitzii in the Idaho Fish and Wildlife Information System database, and five herbarium records for A. cusickii in the Consortium of Pacific Northwest Herbaria database that were located within the study area. We conducted field surveys and EO assessments from 5 to 9 August 2013, when both species were reported to be in flower. We visited known occurrences first, to obtain a search image for each targeted species and their habitats. For each subpopulation or site, we completed the appropriate portion of Idaho Natural Heritage Program's 'Rare Plant Observation Report Form.' This included estimating numbers of individuals and documenting site characteristics, including terrain and disturbances. Survey routes were recorded as Tracklogs.

We relocated four of the five A. cusickii sites, and found three new populations near Heart Mountain. Agastache cusickii sites ranged from <10 to >1000 individuals. Counts were estimated because the slopes were too steep and the substrate was too erosive to walk and map. We determined that the general landscape surrounding subpopulations of each EO was unfragmented, with ecological and hydrological processes intact, and the native plant community within the subpopulations was considered to be intact, with zero to low non-native plant cover and/or minimal anthropogenic disturbance, with the exception of one site (Skull Mountain). We observed two motorcycle trails and noxious and invasive weed species at the Skull Canyon site. Erosion, invasion of non-native species, and climate change are potential threats to A. cusickii habitat.

Six of the seven A. lackschewitzii EOs were relocated, and we surveyed potential habitat on Caribou-Targhee National Forest land near EO 14 in the Beaverhead Mountains. Agoseris lackschewitzii was past flowering during our occurrence assessments. We used keys in an attempt to verify that we were looking at A. lackschewitzii and not A. glauca that had gone to fruit. Though the botanical keys clearly separate A. lackschewitzii from A. glauca in fruit, we found complete overlap in the traits with A. glauca plants that were in fruit and flower. The condition of the area for each EO was still documented, and we determined that the general landscape surrounding subpopulations of each EO ranged from partially to moderately fragmented, with ecological and hydrological processes intact. The typical native plant community within the subpopulations was considered to be intact, with low to moderate non-native plant cover and/or low to moderate anthropogenic disturbance. Cirsium arvense (Canada thistle) was observed in five EOs, seeded grasses; Bromus inermis (smooth brome), Dactylis glomerata (orchardgrass), and/or Phleum pratense (timothy) were documented in two EOs, and an off-highway vehicle trail was observed in one EO. Human and livestock disturbance, noxious and weedy species invasion, and hydrologic regime alteration are threats to A. lackschewitzii habitat. In 2014, we revisited six of the seven A. lackschewitzii EOs from 14 to 17 July, and observed two populations. Sixty-six plants were counted in EO 8, and 14 plants were documented in the vicinity of EO 6 (Targhee Creek), which was a new subpopulation in the area. Effectively managing A. cusickii and A. lackschewitzii is dependent upon detecting and responding to disturbances and threats. Monitoring for rare and sensitive species on the Caribou-Targhee National Forest should be a priority.

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Reference Code: U14MIL03IDUS <br>

Full Citation: Miller, J. J. and C. L. Kinter. 2014. Surveying and Occurrence Assessments for Agastache cusickii (Cusick’s giant-hyssop) and Agoseris lackschewitzii (pink agoseris) on the Caribou-Targhee National Forest. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise. 29 pp. plus appendices. <br>

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

Keywords: Agastache cusickii, Agoseris lackschewitzii, Caribou-Targhee National Forest, eastern Idaho, element occurrence, pink agoseris, Cusick’s giant-hyssop, rare plant conservation <br>