Invasive exotic plant monitoring at Colorado National Monument: 2021 field season

Perkins, Dustin

doi:10.36967/2294260

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 2021. During monitoring conducted June 9–15, a total of 15 priority IEP species in 395 patches were detected on 53.6 kilometers (33.3 mi) of monitoring routes. An additional four species were detected in transects. Yellow salsify (Tragopogon dubius), ripgut brome (Anisantha diandra), jointed goatgrass (Cylindropyrum cylindricum), and tamarisk (Tamarix sp.) were the most commonly detected priority IEPs along monitoring routes, representing 74% of all priority patches. Except for ripgut brome and broad-leaf pepperwort (Cardaria latifolia), most patches of priority IEPs were than 40 m2. Ninety-five percent of tree patches were classified as seedlings or saplings, which require less effort to control than mature trees. Cheatgrass (Anisantha tectorum) was the most common IEP in transects, found in >63% of transects along every route surveyed. When segments of monitoring routes consistently surveyed from 2005 to 2021 were analyzed, Red Canyon, Wedding Canyon, and Fruita Canyon all had the highest number of IEPs per 100 meters during the entire monitoring period. Increases were driven by increases in jointed goatgrass on all three routes and yellow salsify (Tragopogon dubius) in Wedding Canyon and tamarisk in Red Canyon. Jointed goatgrass appears to be rapidly expanding, increasing from 8 patches in 2019 to 42 patches in 2021 (though the routes surveyed were not all the same). In addition, three species not seen in recent years—Canada thistle (Breea arvensis), bull thistle (Cirsium vulgare), and broad-leaf pepperwort—were detected, but in fewer than 10 patches each. These species should be prioritized for control. The No Thoroughfare, Ute Canyon, and Monument Canyon routes all have stayed relatively stable over time, but at least one patch of jointed goatgrass was found on each. Network staff plans to return to re-sample monitoring routes in 2023.

Invasive exotic plant monitoring at Colorado National Monument: 2021 field season

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