Photo © Michael Durham
Importance and Issues
Lemhi penstemon (Penstemon lemhiensis) is found in only four counties in Montana and in adjacent Lemhi County in Idaho. Only three populations have been reported to have more than 300 plants. Big Hole National Battlefield supports the largest known population of Lemhi penstemon. We estimate there are about 2,500 established Lemhi penstemon plants within the Battlefield.
The plant is reportedly in decline due to changes in fire regimes and resulting competition from native and non-native vegetation. Spotted knapweed (Centaurea stoebe) is a threat across the range of Lemhi penstemon and is increasing within the Battlefield.
Periodically estimating the population sizes and reproductive status of both Lemhi penstemon and spotted knapweed will help park managers and answer their questions about penstemon microsite requirements and penstemon and knapweed response to prescribed fire.
Monitoring Objectives
- Estimate the population size and determine population trend of established Lemhi penstemon plants within the Howitzer Hill, Horse Pasture, and visitor center subpopulations.
- Determine the number of basal rosettes per established plant and density of flower stems per established plant as a measure of reproductive vigor.
- Determine trends in the number of seedlings within intensively monitored plots in each of the three subpopulations.
- Estimate ground cover in intensively monitored plots in each of the three subpopulations in order to evaluate hypotheses about microsite habitat conditions, competition, and requirements for successful reproduction.
- Estimate the population size and determine population trend of spotted knapweed plants within the sampling frames of Howitzer Hill and the Horse Pasture.
Source: Data Store Saved Search 3293. To search for additional information, visit the Data Store.
Source: Data Store Saved Search 716. To search for additional information, visit the Data Store.
Source: Data Store Saved Search 877. To search for additional information, visit the Data Store.
Last updated: December 11, 2018