Abstract
The sagebrush steppe ecosystem spans nearly 63 million hectares across the Great Basin and the Colorado Plateau in the western United States. Sagebrush steppe ecosystems support over 200 plant species that in turn support over 350 vertebrates, over 1000 invertebrates, and a range of socioeconomic activities. Native sagebrush steppe plant communities are characteristically dominated by sagebrush shrubs (Artemisia spp.) with a diverse understory of grasses and forbs. Pre-European settlement, fires in the sagebrush steppe were typically small (<500ha) and fire would return to a given area every 30-200 years. The size and frequency of historical fires partially enabled sagebrush steppe to maintain as sagebrush steppe by mitigating invasion of grasses and conifers. However, over the last century there have been several alterations to the historical balance between fire and sagebrush steppe plant communities. Much of the more xeric sagebrush steppe has seen an increase in fire frequency and size over the last century, largely due to invasive annual grasses. In addition to being caused by annual grass invasion, this shift in fire regime also promotes grass dominance – a phenomenon called the grass-fire cycle. The grass-fire cycle reduces sagebrush abundance and fragments the sagebrush steppe ecosystem, causing negative impacts to wildlife, soils, and grazing. To mitigate the grass-fire cycle, the Bureau of Land Management has installed hundreds of kilometers of linear fuel breaks to aid in fire suppression efforts and reduce roadside ignitions and wildfire spread. Linear fuel breaks are fuel reduction projects where current roadside vegetation is replaced with a selection of species that create less fuel load, continuity, and height, and remain green longer into the fire season. This effectively creates a less flammable roadside fuel bed that is less receptive to ignitions and dampens fire spread and intensity. Another valuable tool to aid in mitigating the grass-fire cycle is remote sensing. Several remote sensing products are readily available that provide information on land cover, biomass, and fire severity. This information can help managers make informed management decisions on when and where to prioritize hazardous fuels reduction and rehabilitation projects. This dissertation covers the evaluation of linear fuel breaks at meeting management objectives and goals and the potential of using remote sensing data to monitor live fuel moisture content.