INTRODUCTION

Sagebrush (Artemisia spp.) systems occur through most of the semi-arid western North America and is s considered one of the most imperiled ecosystems in the world (Knick et al 2003). Characterized by relatively low temperatures and precipitation, which comes primarily in the form of snow during the winter, the rate of ecosystem processes is relatively slow as evidenced by the life histories of the associated flora and fauna (Connelly et al. 2011).  However, the rate of change within sagebrush systems has periodically increased beyond natural processes. One example is when Europeans began to pioneer this semi-arid region and subsequently developed agriculture and infrastructure to support settlement.

Currently, only half of the historic distribution of sagebrush land cover persists (Schroeder et al. 2004). Along with the conversion of landscapes from natural sagebrush ecosystems to agricultural lands, Euro-American settlement has resulted in an influx of exotic flora and fauna species (U.S. Fish and Wildlife Service 2013). Countless acres within sagebrush ecosystems are compromised by the presence of exotic vegetation that reduces primary productivity and has resulted in a heightened ignition risk for wildfire – a disturbance for which sagebrush systems are generally not well-adapted. Juxtaposed to the threat of exotic vegetation with too frequent fire cycles, fire suppression has led to increases in conifer encroachment into western sagebrush ecosystems (75 FR 13910 2010). When considering both threats together, i.e., exotic vegetation with increased fire cycles and conifer encroachment, it is difficult to determine which conservation actions are best for the future of sagebrush landscapes.

In eastern portions of the sagebrush biome, a different set of threats predominate. As commodity prices increase private sagebrush lands are at increased risk to conversion to cultivated croplands. Additionally, energy development is a threat as oil and natural gas resources are abundant throughout much of the area. Infrastructural support for energy extraction (e.g., roads, powerlines, associated traffic), leads to fragmentation and direct loss of sagebrush habitats. Renewable energy, such as wind power, can also result in the disturbance and loss of sagebrush habitats and is an increasing threat primarily in eastern, but also throughout, sagebrush systems (U.S. Fish and Wildlife Service 2013).

Much of the remaining sagebrush biome is working agricultural lands, and is commonly used for grazing of domestic livestock.  Interestingly, evidence is mounting that the drivers of ecological function in this fragile system are not only beneficial to wildlife resources but have shared values with sustainable agricultural practices.  Recent unprecedented conservation efforts put forth to ensure long-term population viability of obligate sagebrush species such as sage-grouse (Centrocercus urophasianus; USFWS 2010), present a unique opportunity to evaluate both the biological and socio-economic outcomes of sagebrush conservation actions at a continental scale.

The fate of greater sage-grouse, an endemic and obligate of the sagebrush ecosystem, is directly linked to sagebrush (Connelly et al. 2011). As sagebrush has been lost or degraded, the distribution and abundance of the species have diminished commensurately (Schroeder et al. 2004). Sage-grouse are considered an umbrella species for sagebrush ecosystems, because their life-history requires a heterogeneous landscape of sagebrush species and habitat structure. A variety of sagebrush structure types are necessary for concealing and incubating nests, providing available forage in deep snow, or more open canopy mesic areas for young chicks (Hanser and Knick 2011). Thus, landscapes that contain all of these components are not only beneficial to sage-grouse, but provide resources for other sagebrush obligate and dependent species. Additionally, ecosystem services provided by intact and healthy sagebrush systems benefit society as well as these important species.

SAGEBRUSH ECOSYSTEM SERVICES AND SOCIETY

In light of the various threats, the human and economic dimensions for sagebrush system communities have unique and unprecedented landscape-level dimensions for the western U.S. (Sayre et al. 2012).  Recent theoretical work by Bestelmeyer and Briske (2012) documented the need for resilience-based management of rangelands and is arguably applicable to the sagebrush system specifically, but did not extend the integration of socio-economic components to a distilled threats framework. Some successful efforts are showing positive effects on decision-making outcomes by including local knowledge (e.g., rancher participation in program efforts; Lubell et al. 2013) as well as increasing collaborative capacity (Wilmer et al. 2017).  Integration of the human community impacts within the sagebrush system has multiple elements. Examples of this integration may include, 1) quantifiable economic relationships related to livestock production components (Ritten et al 2010); 2) the need to understand valuation of more qualitative components such as sense of place, community cohesion; 3) anxiety from the contemporary threat of litigation (Wulfhorst et al. 2006) ; and 4) broader trends of changes to culture and landscape structure (Nassauer 1995).

Human communities in the sagebrush system span a rural-to-urban continuum. However, rural communities are typically most directly and disproportionately affected by public lands policy and management of sagebrush systems, and often lack planning resources, resulting in gaps between small municipalities and larger ecosystem services expectations. Moreover, community motivations, incentives, and behaviors to adapt to shifting public policies relating to natural resource management needs (e.g., sage-grouse conservation) vary substantially. In this context, threats to the sagebrush ecosystem can manifest in human dimensions in the form of increased stress or anxiety, impacts to morale and cohesion, intergenerational change affecting management and land-use, as well as perceived constraints on livelihood scenarios. Effects to each scale within the human communities – individuals, families, organizations – manifest relative to social and economic relationships that are based on public lands resource management for western landscapes.

The economic returns of grazing are highly dependent on annual forage production.  The increased presence of exotic annual species, especially cheatgrass (Bromus tectorum), alters both the amount and timing of forage production in these systems.  Cheatgrass specifically limits season of use in that it is palatable to domestic livestock for only in the spring and fall, and limits native forage species, resulting in reduced native biomass production later in the grazing season. Likewise, conifer encroachment into grazing lands negatively impacts both the production of perennial grasses and forbs, and shortens growing seasons due to decreased soil water availability (Miller et al. 2017),  and access to forage production (Schmelzer et al 2014).  The impact of this phenomena results in decreased returns to livestock producers, which ultimately negatively impacts rural communities. Further, changes to precipitation patterns can have a negative impact on livestock production. Cow/calf producers that are forced to liquidate breeding stock in the face of reduced annual forage are impacted as retaining heifers post-drought results in at least a two-year lag before reaching calf sales levels prior to any liquidation. Given forage production responses to growing season precipitation, wetter years do not have the same positive impacts that dryer years have (non-linear response to precipitation). Thus, if annual precipitation becomes more variable, as is predicted under some climate forecasts, the benefits of some wetter years are overshadowed by the increased threats of dryer years and increased evapotranspiration (Polley et al. 2013).

Increasing commodity prices may make sagebrush conversion for cultivation economically viable, potentially creating a conflict on private lands between economic development and habitat conservation.  Fragmentation and loss of sagebrush due to energy development and supporting infrastructure may have negative impacts to agricultural producers through loss of net primary productivity (Allred et al. 2015).  Alternatively, some forms of energy production may increase water availability (e.g. coal bed methane ponds) or provide an additional economic resource to individual landowners (e.g. annual rental fees for wind turbines).  The benefits and costs from energy development,  and resulting conservation efforts implemented for sagebrush dependent species, on land users and owners, and associated economies is poorly understood.

The sagebrush biome provides many other benefits to society beyond forage for livestock production including maintenance of rural economies and lifestyles. Management of these systems is complex as often the trade-offs between these other services (e.g., habitat for wildlife, plant biodiversity, water quality, and resistance to soil erosion), are often not well understood.  While decisions such as the timing and intensity of livestock grazing, and energy development can impact the provision of these other services, exogenous factors such as weather and fire can dramatically shape system evolution over time. Further complicating the problems of management of these large systems is that many of the accrued associated benefits are not market-based making profit-motivated decisions difficult. There are also benefits to people that are not directly tied to the landscape. This landscape is also often defined as a mix of private and public land holdings, with management decisions rarely being coordinated at the landscape level.