Lemhi penstemon monitoring in Big Hole National Battlefield: 2013 annual report
Rodhouse TJ and Stucki DS. 2013. Lemhi penstemon monitoring in Big Hole National Battlefield: 2013 annual report. Natural Resource Technical Report. NPS/UCBN/NRTR—2013/805. National Park Service. Fort Collins, Colorado
Big Hole National Battlefield is home to the largest known population of P. lemhiensis, with estimates ranging from 1,362 to 2,973 established plants (excluding seedlings) over the study period beginning in 2009 (Stucki et al. 2013). In 2013, based on a spatially-extensive sample of 299 belt transects placed at random locations drawn from a spatially-balanced sampling algorithm (i.e., Generalized Random Tessellation Stratified [GRTS]), the population of established plants was estimated to be 2,688 (95% confidence interval 2,098-3,278), up slightly from the 2012 estimate but within the 2012 margin of error. The annual rate of increase in Lemhi penstemon density over the 5 years of study estimated from a regression model was 16%. In 2013, there was a very substantial decline in the number of spotted knapweed plants. This was immediately apparent during field work and verified during analysis. In 2012, the estimated spotted knapweed population had exploded to an estimated 17,000 plants. In 2013, the estimate was only 1,889 (95% confidence interval 1,250-2,528). The decline occurred in the Horse Pasture, where large new infestations were encountered in 2012. A redoubling of effort by park staff to apply herbicide on as many patches of knapweed as possible in 2012 is a likely explanation for this steep decline, with a possible contribution from weather. The winter of 2013 was much drier than in recent years and this may also have contributed to the decline.
- Type
- Published Report
- Authors
- Rodhouse, Thomas; Stucki, Devin
- Date of Issue
- 2013-10
- Publisher
- National Park Service
- Units
- BIHO , NRSS , UCBN
- Keywords
- Lemhi Penstemon Monitoring