Invasive Exotic Plant Monitoring at Fossil Butte National Monument: 2024 Field Season

Ridges blanketed in native vegetation and open valleys define the landscape of Fossil Butte National Monument, reflecting the area’s natural beauty and ecological complexity.

NPS/Amy Washuta

Why Monitoring Matters

Invasive exotic plants (IEPs)—plants that are not native and can quickly spread in new areas—are growing across Fossil Butte National Monument (NM). Species like cheatgrass (Bromus tectorum) and creeping foxtail (Alopecurus ventricosus) are widespread and can crowd out native vegetation, degrade wildlife habitat, and alter the park’s natural scenery. These plants disrupt ecosystems and reduce plant diversity, including the presence of native pollinators. Monitoring IEPs helps park managers target control efforts, protect native species, and maintain ecosystem health. This update highlights current trends, high-risk areas, and ongoing challenges.

At-a-Glance

• 812 infestations of 14 priority invasive plant species were recorded in 2024.
• Cheatgrass and creeping foxtail accounted for 68% of all priority patches.
• Cheatgrass was the most frequently detected species, found on 23 of 137 transects.
• Common hound’s tongue, woolly mullein, and sowthistle were newly detected, despite being on the priority list since 2008.
• Quackgrass, black henbane, and yellow sweet clover have all increased from 2021 to 2024.

What We Found

In 2024, Northern Colorado Plateau Network (NCPN) crews recorded 812 patches of 14 priority invasive plant species along 65.1 kilometers (40.4 miles) of monitoring routes in the monument (Table 1). Cheatgrass and creeping foxtail were the most widespread species. These plants were commonly found along roads and drainages, especially near the Main Park Road, which had the highest infestation density.

What's a priority "IEP"?

Priority invasive species are those identified by park and NCPN staff as having the greatest potential to harm park ecosystems and are the focus of early detection and control efforts.

Table 1. Species observed and infestation size class detected along all monitoring routes, Fossil Butte NM, June 21–25, 2024. NOTE: Orchard grass (Dactylis glomerata) is not a priority species.

Common Name Scientific name	Total # of Infestations	1 to Few Plants	Few Plants– 40 m²	>40– 400 m²	>400– 1000 m²	>1000 m²
creeping foxtail Alopecurus ventricosus	240	6	75	123	28	8
Japanese brome Bromus japonicus	32	1	12	19	0	0
cheatgrass Bromus tectorum	310	0	44	263	1	2
whitetop Cardaria sp.	2	0	1	1	0	0
musk thistle Carduus nutans	19	7	11	1	0	0
Canada thistle Cirsium arvense	24	7	14	3	0	0
field bindweed Convolvulus arvensis	1	0	0	1	0	0
common hound’s tongue Cynoglossum officinale	2	1	1	0	0	0
orchard grass Dactylis glomerata	1	1	0	0	0	0
flixweed Descurainia sophia	33	6	22	5	0	0
quackgrass Elymus repens	73	3	26	44	0	0
black henbane Hyoscyamus niger	20	10	9	1	0	0
yellow sweet-clover Melilotus officinalis	55	14	16	22	3	0
sowthistle Sonchus sp.	1	1	0	0	0	0
woolly mullein Verbascum thapsus	1	1	0	0	0	0
Total	813	58	231	483	32	10
Priority Species, Total	812	57	231	483	32	10

Patterns differed across species and sites. Routes like Main Park Road (22.1 patches/km), West Fork Chicken Creek (18.1 patches/km), and Chicken Creek (16.3 patches/km) had the highest infestation densities. In contrast, Eagle Nest Point Road had no priority species detected in 2024.

Cheatgrass was the most widespread species in transects, present in 23 of 137 transects. While it was frequently encountered, its average cover across all transects was relatively low at 0.06%, with slightly higher presence along the Main Park Road.

What’s a “transect”?

A transect is a straight line that researchers follow, stopping at regular points to record observations about plants, soil, wildlife, or other natural features.

Some species showed notable changes. Japanese brome (Bromus japonicus) declined sharply from previous years, while common hound’s tongue (Cynoglossum officinale), woolly mullein (Verbascum thapsus), and sowthistle (Sonchus sp.) were detected for the first time since monitoring began in 2008.

Despite progress in some areas, infestations remain concentrated along key routes and disturbed areas, underscoring the need for continued monitoring and targeted control. Early detections and shifts in species presence highlight the value of ongoing surveillance across Fossil Butte’s most vulnerable areas.

How We Collected the Data

Crews surveyed 25 monitoring routes from June 21–25, 2024, covering approximately 65.1 kilometers (40.4 miles) (Figure 1). They recorded invasive plant locations, species, and patch sizes. Most routes followed roads, trails, and drainages—areas most likely to be invaded due to frequent disturbance.

Figure 1. Overview of invasive exotic plant monitoring routes at Fossil Butte National Monument, June 21–25, 2024.

NPS/Aneth Wight, Eliot Rendleman

Narrative description of the map showing invasive plant monitoring routes at Fossil Butte NM

Roads and trails shown include the Main Park Road and Ruby Point Road in black and the Chicken Creek Nature Trail and Historic Quarry Trail in purple.

Drainages mapped in blue include Chicken Creek, North Dam Fork, West Fork, East Fork, Smallpox Creek, Matate, Wasatch Saddle, and Red Hill. Additional drainages shown are Moose Bones Canyon, Sage Grouse Lek, Fossil Butte Northwest, Fossil Butte Middle, and Fossil Butte South.

The map legend in the lower left identifies route types with color-coded lines: blue for drainages, black for roads, and purple for trails. The monument boundary is outlined in green. The legend also includes a north arrow, a scale bar in kilometers and miles, and an inset map for location context.

Consistent methods were used to estimate how likely it was to detect each plant species in the field, helping ensure accuracy across different routes and survey teams. Teams walked along each route and documented all visible infestations within a 10–16 meter-wide area, based on the effective detection swath width. Quadrats were placed at set intervals along survey lines to estimate plant cover and soil characteristics.

What’s a “quadrat”?

A quadrat is a small square frame used to closely examine and measure the plants and ground cover in a specific spot.

What Comes Next

Invasive plant densities and species composition differed by route. Main Park Road, West Fork Chicken Creek, and Chicken Creek had the highest densities of priority invasive plants in 2024, while Eagle Nest Point Road had no detections. Cheatgrass and creeping foxtail were the most common priority species, while Japanese brome declined sharply compared to previous years, suggesting progress from ongoing control efforts.

Park managers can use these findings to better detect, manage, and prevent the spread of invasive plants at Fossil Butte National Monument.

---

Information in this article was summarized from Invasive exotic plant monitoring at Fossil Butte National Monument: 2024 field season by D. Perkins. Content was edited and formatted for the web by E. Rendleman.