Led By: Danielle Bilyeu Johnston
Study Area: Horsethief State Wildlife Area
Project Status: Ongoing
Rangeland restoration often fails because native plants do not have enough water to germinate or experience overwhelming competition from non-native annuals, or both.
In another CPW study, researchers discovered that creating rough, pothole-like soil surfaces and adding super-absorbent polymers to the soil helps to improve soil moisture and to reduce competition from non-native plants. Super-absorbent polymers (SAP), compounds that swell when wet, slowly release moisture over time, helping to keep soils wet over a longer period of time. In addition, researchers believe that rough soil surfaces trap seeds in areas where soil moisture is high; aggressive invasive are often less competitive in high-moisture environments.
However, researchers do not know how well these techniques will work together, on a large-scale, and in the presence of livestock and wildlife. Thus, this CPW initiated this study to further test the effectiveness of these techniques under different conditions.
In the previous CPW study, researchers created a rough soil surface using a mini-excavator – an inefficient and expensive process on a large scale. Thus, CPW, in collaboration with WPX Energy, developed a new piece of machinery. Dubbed the “pothole-seeder,” the machine creates mounds and holes in the soil when dragged over the ground. With the help of the pothole seeder, researchers quickly seeded four sample areas. Two of these sample areas also received a SAP treatment.
Pothole seeding worked well to establish diverse grasses and forbs at this site. 3 years post-treatment, pothole-seeded areas more perennial forb cover than unseeded areas. Effects of polymer amendment were not apparent, however.
Results and technology developed from this project will help wildlife managers quickly and effectively restore degraded rangelands.
2014, edge of treatment area. Cheatgrass is evident the untreated area on the right-hand side of the photograph.
Pre vs. Post Treatment Comparison