Author: Otgonsuren Avirmed

Publisher:

Published: 2013

Total Pages: 79

ISBN-13: 9781303470646

Energy development is expanding rapidly in sagebrush ecosystems of Western North America. This ecosystem is a critical habitat for many obligate wildlife species, and contains substantial soil carbon. Although we have some knowledge about how wildlife species are affected by energy development, there is much that remains to be understood about how energy development affects sagebrush ecosystem structure and function. In my research, I explored 1) how fast sagebrush plant communities recover from oil and gas development; 2) how soil organic matter was impacted by historical oil and gas development; and 3) how oil and gas development and wind development affect ecosystem production. My results showed that some components of the sagebrush plant communities recover in ~ 90 years after oil and gas development, but other components to do not recover at all. Sagebrush density recovered in ~65 years, and both grass and shrub cover recovered to pre-disturbance levels in 30 years. However, there was no indication of any recovery of forbs, nor any trend toward recovery. Since forbs represent a critical component of the biological diversity of sagebrush systems, these results indicate that reclamation activities should target forbs to promote plant diversity in sagebrush ecosystems. Ninety years of oil and gas development had no effect on labile, recalcitrant, or total soil organic matter pools. Site specific conditions such as soils texture and shrub-induced heterogeneity explained substantial variance in soil organic matter pools, but the disturbance from oil and gas development showed no significant impact. While the disturbance had no effect on soil organic matter, it did eliminate the heterogeneity associated with individual shrubs. I found that shrub-induced heterogeneity recovered in about 45 years in loamy sand soils, but in sandy soils, heterogeneity did not recover. On the other hand, the insignificant effect of disturbance on soil organic matter leads us re-think modern well development practices: other studies on recent oil and gas sites show substantial losses of soil organic matter in soils that have been removed, stockpiled, and replaced, due to the physical disturbance of soils. This raises into question some of the current reclamation practices and their influence on soil organic matter, relative to pre-reclamation development. Evaluation of the landscape scale impacts of energy development did not show effects on aboveground production as measured by the annual integral of NDVI. Inter-annual variability had significant effects on both NDVI and seasonality of production. Wind farms, located in higher elevations tend to have higher production than oil and gas wells. More evaluation of remotely sensed indicators of ecosystem structure and function will be important, including growing season NDVI.