Trend Monitoring of Spalding’s catchfly (Silene spaldingii S.Watson) at Craig Mountain Key Conservation Area (KCA), Craig Mountain, Idaho

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Spalding’s catchfly (Silene spaldingii S.Watson) is a federally-listed Threatened plant species endemic to the mesic bunchgrass grasslands in eastern Washington, west-central Idaho, northeastern Oregon, and the intermontane valleys in Montana [U.S. Fish and Wildlife Service (USFWS) 2001]. Recovery actions for this Threatened species include the designation of Key Conservation Areas (KCAs) to maintain reproducing, self-sustaining populations of this species. Long-term trend monitoring is employed to determine whether populations are increasing, decreasing, or remaining stable over time. This monitoring requires the determination of the total number of plants at a site at a point in time and comparing it with counts of total plants at future points in time. Obtaining total plant counts for this species at a site is challenging, i.e., it has a dormant stage that is invisible belowground, a major aboveground stage that is small and located on the ground surface, and a large percentage of aboveground plants that disappear by flowering time (Hill 2012; Hill et al. 2014; Hill and Garton 2015, 2017). <br>

The largest KCA in Idaho is the Craig Mountain KCA within the Canyon Grasslands of the Snake and Salmon Rivers in west-central Idaho. This KCA currently consists of ~5,000 known plants across an area of ~3,500 acres and is comprised of five Spalding’s catchfly Element Occurrences (EOs): Garden Creek Ranch EO 6, Madden Creek EO 9, Captain John Creek EO 10, Billy Creek EO 16, and Eagle Creek EO 19. Two long-term trend monitoring studies, one for the Bureau of Land Management (BLM) initiated in 2002 and the other for USFWS initiated in 2004, are being conducted within 16 monitoring transects/plots in four of the Spalding’s catchfly EOs at the Craig Mountain KCA. The total number of plants at each site was determined by monitoring once in early June for two consecutive years (preferred method); however, a close estimate of total plants can be obtained in one year of monitoring. Obtaining accurate information depends on two critical criteria: 1) monitoring early in the growing season (first two weeks in June) when all plants emerging aboveground for the growing season are present before they start to disappear, and 2) counting all aboveground plants, including the approximately one-third of plants that emerge in the small rosette stage class (this requires close examination of the ground surface). Three trend monitoring readings with 6- to 7-year intervals between them have been conducted to date. Results of statistical analyses of these three trend readings demonstrate a significant decrease in plant numbers in the transects/plots for both studies over the past 13-15 years. This decrease is likely associated with cycles of high rodent activity and increases in the number of wildfires during this time period. <br>

To ensure continuity and accuracy and guide future trend monitoring at the Craig Mountain KCA, important criteria and protocols utilized for this monitoring are discussed. Methodologies, plot design layouts, and suggested field data forms for both the BLM study and the FWS study are provided, as well as a suggested logistical plan for monitoring all 16 transects/plots within the required time frame of the first two weeks in June. <br>

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Reference Code: U20HIL04IDUS <br>

Full Citation: Hill, J., J. Lichthardt, and L. Kinter. 2020. Trend Monitoring of Spalding’s catchfly (Silene spaldingii S.Watson) at Craig Mountain Key Conservation Area (KCA), Craig Mountain, Idaho. Idaho Natural Heritage Program, Idaho Department of Fish and Game, Boise, Idaho. 28 pp., plus appendices. <br>

Location: ELECTRONIC FILE - BOTANY: PLANT SPECIES: Silene spaldingii <br>

Keywords: BLM Study, Craig Mountain KCA, FWS Study, Key Conservation Area, rare plant conservation, Silene spaldingii, Spalding’s catchfly, trend monitoring <br>