Invasive exotic plant monitoring in Capitol Reef National Park: 2020 and 2021 field seasons

Abstract

Invasive exotic plant (IEP) species are a significant threat to natural ecosystem integrity and biodiversity. 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 moni-toring protocols to be implemented as part of its long-term monitoring program. From June 5 to July 29, 2020, and May 30 to June 2, 2021, network staff conducted surveys for priority IEP species along the Oak Creek, Pleasant Creek, and State Route 24 monitoring routes at Capitol Reef National Park. We detected 834 patches of 11 priority IEP species along 67.9 kilometers (42.2 miles) of three monitoring routes. There were more patches of tamarisk along State Route 24, and a higher percentage of large patches, than in previous years. This indicates that previously identified IEP patches have expanded and grown. Field bindweed (Convolvulus arvensis) and Russian olive (Elaeagnus angustifolia) along State Route 24 have both increased in prevalence since monitoring began. Tamarisk (Tamarix sp.) was the most prevalent prior-ity IEP species on all three routes. On Oak and Pleasant creeks, there were fewer than three patches of all other IEPs. On State Route 24, there were 30 or more patches of Russian olive, quackgrass (Elymus repens), field bindweed, and blue mustard (Chorispora tenella). IEP prior-ity species were found on 71%, 47%, and 62% of transects along Oak Creek, Pleasant Creek, and State Route 24, respectively. Yellow sweet-clover (Melilotus officinalis) was the most fre-quently observed IEP on Oak Creek and Pleasant Creek. Percent cover was highest for yellow sweet-clover, Russian thistle (Salsola sp.), and tamarisk on Oak Creek, Pleasant Creek, and State Route 24, respectively. The NCPN plans to return to Capitol Reef in 2023 to continue the fourth rotation of invasive plant monitoring.