This topic focuses on factors that influence sagebrush ecosystem resilience to disturbance and resistance to nonnative invasive annual grasses and the distribution and relative abundance of sage-grouse populations in order to help address persistent ecosystem threats, such as invasive annual grasses and wildfire, and anthropogenic threats, such as oil and gas development and cropland conversion, to develop effective management strategies. Note that these threats can interact with each other; for example, oil and gas development can increase the spread of invasive annual grasses and potential for wildfire, and invasive annual grasses can increase the difficulty of restoring sites impacted by oil and gas development.
The primary geographic areas of focus of this lesson are Management Zones I, II, and VII (Northwestern Great Plains, Wyoming Basins, Southern Rockies), shown in this map (Chambers et al. 2016, Figure 1). Greater Sage-Grouse are not equally distributed across this portion of the sage-grouse range; Doherty et al. (2011) estimated that about 64% of eastern sage-grouse habitat is in Wyoming, 24% in Montana, and 8% in Colorado. The eastern range contains the entire geographic range of the Gunnison Sage-Grouse (Centrocercus minimus), though similar management considerations apply to that restricted-range species.
The eastern range differs from the western range in the magnitude of ecosystem versus anthropogenic threats and encompasses a different set of climatic regimes and vegetation types. Of particular importance for fuels management, the annual grass/fire cycle and increased fire frequency are not yet as problematic in the eastern range as in the Great Basin and western portion of the range, but conversion to invasive annual grasses is an increasing problem in some areas (Chambers et al. 2016). However, increasing land conversion and development in the eastern range fragments habitat and promotes establishment of invasive species such as cheatgrass, which may lead to increasing wildfire. Therefore, fuels management considerations such as those from the Great Basin can be expected to increase in the future as development of all kinds increases.
Figure 1 Click the image for a printable verison.
Many reviews of the effects of anthropogenic threats on sage-grouse are available (for example, Knick and Connelly 2011, Hanser et al. 2011, Manier et al. 2014). Examples of such threats found in the eastern range include energy development, conversion to cropland, livestock grazing, mining, and urban, suburban, and exurban development (Chambers et al. 2016). This topic focuses on persistent ecosystem threats and the secondary effects of land use and development on ecosystems such as invasion of nonnative species since these are the ones for which vegetation management is most important. The same types of ecologically-based approaches used to manage persistent ecosystem threats can be used to minimize impacts and increase restoration effectiveness of habitats affected by land use and development. Handbooks and guides for implementing fuels management are available for the western portion of the sagebrush biome that can be adapted to the eastern portion of the sagebrush biome (Miller et al. 2014, 2015; Pyke et al. 2015a, b, 2017).
Concerns of fire and fuels managers in the eastern range include large fires in or adjacent to sage-grouse habitats, increases in woody plant expansion, and increases in the extent of nonnative annual grass populations. Currently there is little evidence of the same type of feedback cycle between wildfires, annual grasses, and larger fire size as exists in the western portion of the range (see Invasive Species lesson). However, managers are aware of this potential and are monitoring trends in fire size, post-fire community composition, and rehabilitation success to detect the development of this type of cycle and adapt management to ensure positive future trends.
Proactive fuels management practices in the eastern range differ from those in the western range. For example, roadside linear fuel breaks are seldom used in the eastern range, while they are more commonly used in the western range. While conifer expansion in the western range is largely pinyon and juniper species, expanding conifers in the eastern range include limber pine (Pinus flexilis), Douglas fir (Pseudotsuga menziesii), and ponderosa pine (Pinus ponderosa). In addition, successional advancement of mountain shrubs (e.g., gambel oak [Quercus gambelii], serviceberry [Amelanchier spp.], curlleaf mountain mahogany [Cercocarpus ledifolius], snowberry [Symphoricarpos spp.], cliff fendlerbush [Fendlera rupicola]) in the Southern Rockies (MZ VII) into sagebrush communities is treated as a vegetation management issue.
Mechanical treatments of expanding conifers, which include mastication and chainsaw treatments, are increasingly used in the eastern range. Prescribed burning is a fuels management tool which is selectively applied in the eastern range to: (1) reduce downed woody fuels resulting from mechanical treatments; (2) treat expanding conifers; (3) convert conifer woodlands to shrub-steppe; (4) reduce the dominance of mountain shrub communities to favor sagebrush; (5) create age class and structural diversity within sagebrush communities; and (6) restore riparian systems through multi-phased treatments. Managers need to be cognizant of the tradeoffs related to sagebrush removal through burning, and apply this tool in consultation with wildlife managers and in consideration of site conditions. Additional fuels management practices in the eastern range include monitoring and treating areas with invasive annual grass populations with herbicides and seedings where insufficient perennial grasses and forbs exist for recovery and installing fuels breaks, which can complement fire suppression effectiveness.
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