Energy Development Promotes Presence of Non-Native Plant Species in the Williston Basin

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The presence of non-native plant species is significantly greater adjacent to oil well pads than in non-developed areas of the Williston Basin, according to a first-of-its-kind U.S. Geological Survey study for this area.

Image: Invasives Williston
A stand of field sow thistle (yellow flowers; Sonchus arvensis), Canada thistle (purple flowers; Cirsium arvense), and Kentucky bluegrass (grass; Poa pratensis), all of which are non-native and growing near an oil well pad in Mountrail County, ND.Public domain

BOZEMAN, Mont. – The presence of non-native plant species is significantly greater adjacent to oil well pads than in non-developed areas of the Williston Basin, according to a first-of-its-kind U.S. Geological Survey study for this area. 

While previous studies have documented increased presence and abundance of non-native plant species in areas undergoing energy development, this was the first such assessment in the U.S. portion of the Williston Basin, which is experiencing rapid energy development and includes portions of Montana, North Dakota and South Dakota as well as Saskatchewan and Manitoba.

Noxious weeds and other non-native plant species compete with native plants for limited soil and water resources, degrade habitat, reduce forage for wildlife and livestock, and can reduce agricultural yields.  Those specifically identified as noxious weeds are designated by a federal, state or county government as injurious to public health, agriculture, recreation, wildlife or property.

“If the 58,485 oil wells expected in North Dakota were all installed on typical 5 acre well pads, it would equate to an area roughly the size of the city of Los Angeles.” said Todd Preston, research associate contractor at USGS and author of the study. “We wanted to assess whether or not this broad geographic level of disturbance may provide a pathway for the establishment of non-native plants.”

In the study, Preston conducted vegetation surveys at 30 oil well sites and 14 non-developed sites in native prairie environments across the Williston Basin. The number of individual non-native species and the amount of non-native plant cover was assessed at all sites. 

Non-natives were recorded at all 44 sites and were significantly greater at oil well sites compared to non-developed sites. The age of the oil well pad also had a significant influence on non-native plant species presence and cover.  Younger well pads had more non-native species relative to older well pads, likely due to how non-native plant species compete with native vegetation and other non-natives over time.

Image: Invasives Williston
A large strand of non-native prickly lettuce (Lactuca serriola) grows near a well pad in Dunn County, ND.Public domain

“Of the several non-native species that rapidly colonize the disturbed area around the well pad, some become established while others are unable to persist,” said Preston. “However, the presence and abundance of non-natives was still greater at the older wells compared to undeveloped sites, demonstrating that changes in vegetation communities are still visible a decade after well pad construction.”

In an effort to assist land managers, the study identified non-native species whose presence and/or abundance were significantly greater at oil well sites relative to non-developed sites.

“This study identified 11 non-native species, with 5 of these species listed as noxious weeds, that were more common or more abundant near oil wells, and these results could help land managers focus reclamation and weed control efforts for future energy development,” said Preston. 

The article, published in Environmental Monitoring and Assessment, is titled “Presence and Abundance of Non-Native Plant Species Associated with Recent Energy Development in the Williston Basin” and can be viewed online.  

This study was supported by the Plains and Prairie Pothole Landscape Conservation Cooperative.

More information about impacts of energy development on plains and pothole environments in the Williston Basin can be found on the USGS website.