Invasive exotic plant monitoring in Colorado National Monument: 2017 field season

Gommermann, Luke; Perkins, Dustin; Washuta, Amy

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. This report represents work completed at Colorado National Monument during 2017. During monitoring conducted June 1–7, a total of 20 IEP species were detected on monitoring routes and transects. Of these, 11 were priority species that accounted for 590 separate patches. IEPs were most prevalent along riparian areas. Yellow sweetclover (Melilotis officinale), yellow salsify (Tragopogon dubius), and woolly mullein (Verbascum thapsus) were the most commonly detected priority IEPs, representing 86% of all priority patches. Patches of less than 40 m2 were typical of nearly all priority IEP species except yellow sweetclover. A patch management index (PMI) was created by combining patch size class and percent cover for each patch. A large majority (89%) of priority IEP patches were assigned a “Very Low” PMI, indicating small and/or sparse patches where control is generally still feasible. The number of patches of Russian olive (Elaeagnus angustifolia) and Siberian elm (Ulmus pumila) continued to decrease compared to those observed in the first year of NCPN monitoring (2009) and earlier (2003) survey efforts by Utah State University. Patches of tamarisk (Tamarix sp.) rose slightly in number from 2015. In addition, 92% of the tree patches were classified as seedlings or saplings, which require less effort to control than mature trees. Cheatgrass (Anisantha tectorum) had the highest average percent cover (1.1%) and highest frequency (64%) of all IEPs across all transects. When treated and untreated extra areas in the West Entrance area were compared, the treated area had more species per quadrat, higher overall percent cover, and nearly three times as many patches per hectare than the untreated area—but the patches were generally of a lower PMI, indicating they were likely newer and potentially easier to control. Park staff should consider adding revegetation efforts shortly after invasive plant control to prevent new establishment of invasive plants. Comparing segments of monitoring routes conducted between 2003 and 2017 or 2009 and 2017 indicated woolly mullein and yellow sweetclover were increasing, while tamarisk and Russian olive were decreasing. Network staff will return to re-sample all monitoring routes in 2019.

Invasive exotic plant monitoring in Colorado National Monument: 2017 field season

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