Invasive exotic plant monitoring at Dinosaur National Monument: Yampa River and the Echo Park and Mitten Park extra area, 2017 ﬁeld season

Washuta, Amy; Perkins, Dustin; Gommermann, Luke

Invasive exotic plant (IEP) species are a signiﬁcant threat 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. During surveys conducted along 76 transects from June 29 to July 6, 2017, NCPN staﬀ detected 11 priority IEP species and two non-priority species in a 92.1-hectare (228-acre) area along 76.0 kilometers of the Yampa River in Dinosaur National Monument. A total of 1,357 IEP patches were detected. Of those patches, 62.7% were smaller than 40 m2 and 96.9% had a patch management index (PMI) of very low/low. Patch management index is a new tool that combines the size and density of an patch to assess its scale. Very low or low PMI indicates that chances for eradication of these patches is possible. Tamarisk (Tamarix sp.) and yellow sweetclover (Melilotus officinalis) were widespread. Musk thistle (Carduus nutans), Russian knapweed (Centaurea repens), Canada thistle (Cirsium arvense), leafy spurge (Euphorbia esula), and broadleaf pepperwort (Lepidium latifolium) were also common along the Yampa River. Whitetop (Cardaria sp.) and black henbane (Hyocyamus niger) were found in 2017 but not in the 2010 survey of the same area. From 2010 to 2017, there were general increases in yellow sweetclover, musk thistle, and Russian olive (Elaeagnus angustifolia), and a decrease in broadleaf pepperwort. The number of tamarisk and leafy spurge patches increased, but this was at least partially offset by a decrease in their size and PMI. Cheatgrass (Bromus tectorum) increased substantially in frequency and percent cover within transects along the Yampa River from 2010 to 2017. In the Echo Park and Mitten Park extra area along the Green River, nine IEP priority species were detected in a 31.1-hectare (77-acre) search. Tamarisk and broadleaf pepperwort were the most widespread IEPs in these areas. Musk thistle, Canada thistle, yellow sweetclover, bull thistle (Cirsium vulgare), and Russian knapweed were also common. Comparisons to previous monitoring efforts on the Green River will be completed when the entire Green River section below the confluence has been surveyed.

Invasive exotic plant monitoring at Dinosaur National Monument: Yampa River and the Echo Park and Mitten Park extra area, 2017 ﬁeld season

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