Invasive exotic plant monitoring at Fossil Butte National Monument: 2021 field season

Abstract

Invasive exotic plant (IEP) species are one of the biggest threats to natural ecosystem integrity and biodiversity, and controlling them is a high priority for the National Park Service. The Northern Colorado Plateau Network (NCPN) selected the early detection of IEPs as one of 11 monitoring protocols to be implemented as part of its long-term monitoring program. This report represents work completed during the 2021 field season at Fossil Butte National Monument (NM). From June 26 to 29, 2021, we recorded a total of 12 different priority IEP species during monitoring. A total of 763 priority IEP patches were recorded along 61.9 kilometers (38.5 mi) of 22 monitoring routes. Summer cypress (Bassia scoparia) was detected for the first time on monitoring routes along the Main Park Road. The highest densities of IEP patches were detected in several drainages and one trail: Sage Grouse Lek Drainage (32.7 patches/km), East Red Hill Drainage (19.4/km), Moose Bones Canyon (19.4/km), Main Park Road (19.0/km), West Fork Chicken Creek (17.6/km), Chicken Creek (15.0/km), Smallpox Creek (13.5/km) and the Historic Quarry Trail (11.1/km). The Fossil Butte Northwest, Wasatch Saddle, and North Dam Fork of Chicken Creek drainages were the only routes free of priority IEPs in 2021. Cheatgrass (Bromus tectorum), creeping foxtail (Alopecurus arundi-naceus), and Japanese brome (Bromus japonicus) were the most widespread species. Creeping foxtail continues to increase parkwide and along the Main Park Road and southern drainages. The two brome species have declined somewhat since 2018, but these species can fluctuate widely based on precipitation. Flixweed (Descurainia sophia), whitetop (Cardaria sp.), and quackgrass (Elymus repens) all appear to have declined since 2018 and their previous highs in earlier years. Control efforts by park staff are likely helping to prevent some IEP increases in the park. Network staff plan to return to Fossil Butte NM for an eighth round of monitoring in 2023.