Weed Establishment and Persistence after Water Pipeline Installation and Reclamation in the Mixed Grass Prairie of Western North Dakota

Weeds in reclamations interfere with success by: 1) competing with desirable species seeded during revegetation; 2) preventing recolonization of reclamations by native species; and 3) reducing the integrity of landscapes by expanding from reclamations into adjacent, intact areas. In the Bakken oilfield of western North Dakota, dispersed reclamation activity and increased traffic may provide many opportunities for weeds to spread. To determine the potential for disturbance and reclamation to increase resident weed populations and introduce new weed species, we tracked twenty-one weed (non-native/ruderal/invasive) species over a four-year period after the installation of a 1.8 km livestock water pipeline and subsequent land reclamation on a historic ranch in western North Dakota. We included areas of historic (early 20th century homestead) and recent (prairie dog town) landscape disturbances and tracked weed frequency and density in the disturbed pipeline and in the directly adjacent intact prairie. Most of the weeds in the pipeline were non-persistent populations of naturalized species. Our data show that although naturalized weeds may respond positively to disturbance, they can quickly return to pre-disturbance levels. However, disturbance may have resulted in the introduction of one new noxious weed, Hyoscyamus niger (black henbane). Agropyron cristatum (crested wheatgrass), an invasive, non-native perennial grass that reduces native plant diversity and forage value, was also introduced. This study demonstrates the importance of prevention of weed dispersal during disturbance and reclamation, contamination-free seed sources, and post-reclamation follow up to control any weeds that may have been introduced as a result of pipeline development