Overcoming barriers to native shrub establishment on abandoned oil and gas pads on the Colorado Plateau
Maxwell, Logan M.
Dryland ecosystems are increasingly disturbed by human land use practices such as oil and gas extraction. These operations degrade fragile landscapes through removing vegetation and topsoil, which can lead to increased soil compaction and salinity. If affected sites are abandoned after use without reclamation efforts, recovery of native shrubs may take decades. Thus, understanding the barriers to native plant growth and recovery are important for implementing restoration techniques. Using a chronosequence approach to survey abandoned oil and gas pads in Wyoming sagebrush and blackbrush habitats, I evaluated the physiological status of mature shrubs (i.e., predawn water potentials and photosynthetic rates), soil compaction and salinity on abandoned oil and gas pads, compared to off pad reference sites to determine if these qualities changed differentially over time. I also determined whether soil compaction or salinity affected shrub water and photosynthetic processes. In both sagebrush and blackbrush communities, predawn and mid-day water potentials were higher on pads, whereas shrub density was reduced. Plant and soil qualities did not change with time since abandonment, except for blackbrush surface soil moisture which was less dry over time. Increased soil compaction reduced predawn water potentials for plants on pads in blackbrush communities. Salinity was higher on sagebrush pads, but it did not negatively affect shrub physiological status. However, increased salinity in blackbrush communities negatively affected photosynthetic rates for plants on pads. Over time, plant density did not increase, suggesting that there is little dispersal of new recruits away from parent plants. Although poor soil conditions may affect some physiological indicators for mature plants, there is also a lack of shrub density increase over time. The current patterns of establishment suggest that there are low dispersion distances away from established plants, suggesting that new germinants may be affected more by poor soil qualities.
Restoration, Oil and gas disturbance, Wyoming sagebrush, Blackbrush
Maxwell, L. M. (2021). <i>Overcoming barriers to native shrub establishment on abandoned oil and gas pads on the Colorado Plateau</i> (Unpublished thesis). Texas State University, San Marcos, Texas.