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Cheatgrass beside the tracks at Golden Spike National Historical Park. NPS.
Invasive exotic plants are among the most serious threats to national park resources. The Northern Colorado Plateau Network (NCPN) watches for them where they usually arrive first: along roads, trails and waterways.
Why and how
Invasive exotic plants (IEPs) are species whose introduction "does or is likely to cause economic or environmental harm or harm to human health." They spread quickly, displace native plants and leave gaps that ripple through the ecosystem. Caught early, small populations can be eradicated, cheaply.
In eight park units, the NCPN lists priority species for each park, surveys set routes on a rotating schedule, and sets up plots to track trends. Each patch gets a Patch Management Index (PMI) — patch size × weed cover — from very low to very high, read together with species and patch counts.
Golden Spike, 2018
On July 2–4, 2018, crews surveyed 20 km (12.4 mi) of 13 routes and 42 transects.
- 17 invasive species in all; seven priority species in 73 patches; three more species only in transects.
- 96% of patches rated very low or low PMI — local control or eradication looks feasible.
- Scotch thistle was the most common priority species, 51% of patches, followed by field bindweed, rush skeletonweed and moth mullein.
- Broad-leaf pepperwort and Canada thistle turned up (one patch each) for the first time since 2014.
| Species | |
|---|---|
| Scotch thistle (Onopordum acanthium) | priority |
| Field bindweed (Convolvulus arvensis) | priority |
| Rush skeletonweed (Chondrilla juncea) | priority |
| Moth mullein (Verbascum blattaria) | priority |
| Canada thistle (Cirsium arvense) | priority |
| Dyer's woad (Isatis tinctoria) | priority |
| Broad-leaf pepperwort (Lepidium latifolium) | priority |
| Crested wheatgrass, cheatgrass, tumble mustard | transects only |
| Summer cypress, rattlesnake brome, Japanese brome, tansy mustard, yellow sweetclover, Russian thistle, yellow salsify | not priority |
Trends (patches per km):
| Year | Patches per km |
|---|---|
| 2010 | 2.33 |
| 2012 | 0.36 |
| 2014 | 4.96 |
| 2016 | 3.43 (67 patches) |
| 2018 | 3.74 (73 patches) |
The densest routes were the Hydro 1 (20.3 per km) and Last Cut (10.7) drainages and the Retired Service (11.5) and Facility (7.4) roads.
Invasive plant patches along Golden Spike's monitoring routes, July 2–4, 2018. NPS.
Network staff planned to resurvey all routes in 2020.
Sources
Based on "Invasive Exotic Plant Monitoring at Golden Spike National Historical Park, 2018," Northern Colorado Plateau Network, National Park Service, summarizing A. Washuta and D. W. Perkins's report; a work of the United States government in the public domain. Its Scotch thistle photograph, credited to the University of Connecticut through Bugwood.org, is left out.
Licence : CC0 1.0 (domaine public) · Adapté de www.nps.gov
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