The American West as a social-ecological region: drivers, dynamics and implications for nested social-ecological systems

The concept of SESs is not new generally (Marsh 1864), nor to research on the American West specifically (for one example, see Ingram 1990). In the past two decades, however, there has been an upswell of scholarship aimed at building a more explicit recognition of the linkages between social and ecological systems both conceptually and empirically as a means of establishing a common framework from which to work toward global sustainability goals (Folke et al 2005, Ostrom 2009, Fischer et al 2015). Despite the increase in SES analyses, spatially explicit approaches for delineating, characterizing and analyzing SESs are still relatively rare (for a few examples, see Ellis and Ramankutty 2008, Martín-López et al 2017). Here we attempt to address to this gap, by characterizing the West as a social-ecological region, thereby providing a consistent place from which to further analyze and compare the intra- and inter-system dynamics of SESs nested within the region. In this conceptualization, there are many specific SESs nested within a region organized by a critical set of variables and influenced by cross-scale interactions (including with forces operating at much larger scales, like global climate variability and economic structures) (Gunderson and Holling 2002, Walker and Salt 2006).

To operationalize the West as a social-ecological region, we draw on definitions from Chapin et al (2009) to define three types parameters that characterize SES dynamics over space and time: exogenous factors, slow variables, and fast variables. Exogenous factors are those that 'remain relatively constant over long time periods and across broad regions and are not strongly influenced by short-term, small-scale dynamics' (Chapin et al 2009: 5). Exogenous factors, when taken together, set the parameters for a social-ecological region and provide a foundation for understanding dynamics within varying types of embedded SESs (Metzger et al 2010, Leslie et al 2015). Fast variables refer to aspects of SESs that change rapidly over space or time, and generally show much greater variation or instability than do slow variables. Major changes in fast variables can also be thought of as internal perturbations within an SES, which have as much potential to alter the state of the system as do external perturbations (e.g. unanticipated climate disturbances). Slow variables are those that remain relatively constant over years to decades, (often what are referred to in ecology as 'state' variables), and we thus engage with slow variables only to describe consistent characteristics of specific SESs.

We conceptualize the West as a social-ecological region defined principally by three key exogenous factors that differentiate it from other regions of the United States: aridity, topography, and a unique political economy of land ownership, tenure and management (figure 1). We also highlight several fast variables that are associated with contemporary SES dynamics within the West, including changes in population density, economic activity, and natural hazards such as wildfire and drought. Figure 1 presents a conceptual visualization of the nested nature of social-ecological regions and SESs, and their multi-scalar dynamics. In addition to the regional exogenous factors that drive SES dynamics in the West, we recognize that there are extra-regional, macro-scale drivers of change (e.g. climatic change, global markets) that influence the West in specific ways and that interact with the exogenous factors and fast and slow variables. We define and discuss these macro-scale drivers throughout the rest of this paper as appropriate and highlight how they condition the characteristics of both the region and the specific SESs nested within the West.

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Using publicly available data, we identify indicators of each exogenous variable that we hypothesize defines the West, and then employ cluster analysis to explore the co-occurrence of average 'levels' of each variable. We are testing the hypothesis that the West as it is understood in the popular imagination is in fact a region that can be characterized as more arid, more topographically complex, and with more public land than other regions of the country. As an indicator of aridity, we use climate water balance data (Dobrowski et al 2013) and a measure of water deficit (in mm). As an indicator of topography, we use WorldClim Global Climate Data V1 (Hijmans et al 2005), and refactor the elevation data to create an index of topographic complexity, calculated the range of elevation in a moving window around each gridcell and transformed that range into a 0–1 index (with values approaching 0 indicating more complexity or variation). Finally, as an indicator of the political economy of land, we use a measure of the proportion of land per county that is owned by the federal government using the Gap Analysis Program Protected Areas Database v 10.3 (Gergeley and McKerrow 2013). The political economy of land tenure and management in the West includes federal policies that reserved large expanses of surface and subsurface resources for state ownership and management, and privileged a particular set of beneficiaries while dispossessing Native communities of their land and associated resources (White 1991, Wilkinson 1993, Robbins 1999, Gaido 2002, Hixson 2013, Bonds and Inwood 2016). Political economy cannot be measured directly, and so we use the proxy of federal land ownership to represent the 'footprint' of this legacy on the West (Spence 1999, Vincent et al 2017).

At the top of figure 2 we present the distribution of each of the three variables separately, as they are originally measured. We then refactor those measures to the county level to conduct cluster analysis. Cluster analysis was performed using the k-means algorithm, since all three variables are continuous measures. We used multiple fit statistics to guide our decision about the best-fitting number of clusters (Martín-López et al 2017). We chose to interpret three clusters based on average silhouette method, which is a measure of cohesion across all three variables among cases (counties) within each cluster. Average silhouette width of the three-cluster solution presented here is roughly 0.57, which is generally considered a reasonable fit (for an overview of cluster analysis methods, see Chatfield and Collins 2018). Details of multiple fit statistics, cluster averages and boxplots to show the distribution of each variable within each cluster are provided in the supplementary material. All analysis was conducted in R (R Core Team 2019) using the cluster (R version 2.0.9) (Maechler et al 2019) and factoextra (R version 1.0.5) (Kassambara and Mundt 2017) packages. Map visualizations were done in ArcGIS Desktop (version 10.7) software.

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Figure 2 shows the distribution by county of the three cluster classes that operationalize the three key exogenous variables which, we hypothesize, together define the American West. The red counties (Cluster ID 3) are those with high aridity, high topographic complexity, and a large proportion of federally owned land. As can be seen from the map, this cluster of counties largely aligns with both popular conceptions and past research that defines the West as a contiguous geographic region that lies west of the 100th meridian. However, there are also counties that have more water than is the norm (Cluster ID 2)—largely those areas along the Pacific Coast—and counties having more water, less topography and less federal land (Cluster ID 1). The results in figure 2 also demonstrate that there are places elsewhere in the United States characterized by the presence of high topographic relief, high aridity and high proportions of federal ownership (Cluster ID 3), largely in Appalachia and areas around the Great Lakes. What makes the West a region then, is a set of exogenous variables that co-vary across a large contiguous area—a social-ecological region.

Within the West, as defined analytically and presented visually in figure 2, there are many fast variables that create highly heterogeneous conditions across the region and are conditioned by the exogenous factors identified above. In this section, we explore and describe variation social and ecological variables reflective of dominant narratives about the new and old West, and the natural hazards pressures facing the region (Otterstrom and Shumway 2003, Winkler et al 2007, Schoenagel et al 2017, Anderson et al 2018). We select two social and two ecological variables: population change over the past eight years (2010–2017 US Census Bureau 2017), dominant economic activity as of 2015 (ERS 2017), large fire activity from 1984–2016 (USGS and USFS 2018), and total number of weeks in which drought occurred from January 2015 to January 2019 (NDMC, USDA and NOAA 2019). Population change, economic activity and drought data are at the county level, whereas data on large fire activity are polygons representing the perimeters of the fire.

The maps in figure 3 demonstrate that fast variables vary within and across the West (maps include a mask that highlights areas that fall in the West as defined in the cluster analysis and map in figure 2). The maps in figure 3 show that on the ecological side, drought is a consistent characteristic of the region, with most of the region experiencing drought for almost half of the total period measured. Fire activity is more variable, with a much higher density and total area of fire sites in the northern Rocky Mountains and the extreme southwest. On the social side, figure 3 shows pockets of relatively high population gain, a few specific places of high population loss, and many counties with moderate gain or loss. Importantly, population gain and loss occurs in a patchwork fashion, in contrast to other parts of the country with large contiguous areas of population loss and small pockets of gain. A similar patchwork exists for dominant economic activity, with recreation scattered along the Rocky Mountain front, mining existing in the Intermountain interior, and very little manufacturing anywhere in the region.

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Taken together, the maps in figure 3 provide a starting point for understanding where there is potential variation in some key SES dynamics across the West. For example, population change is highly variable from county to county within the region, and many counties have remained relatively stable in terms of population (challenging the rapid urbanization narrative). Dominant economic activity within the West is much more varied than in other parts of the country and provides one representation of the existence of both the old and new West, side by side (see also Winkler et al 2007). On the ecological side, drought (the impact on human systems of aridity) is a consistent characteristic of most of the region and represents the extreme operationalization of aridity, which as an exogenous variable has shaped the biophysical landscape over longer time horizons. Drought ebbs and flows on an annual basis, and has consequences for agricultural and recreational livelihoods, while aridity is a consistent feature of the region to which SESs have adapted over time. Large fire activity, increasing in severity and driving human decision-making in the West, appears to also cluster in certain parts of the region more than others, making it an acute driver in specific locations but not necessarily a key management concern across the entire region (Anderson et al 2018).

Agriculture is an important component of historical and contemporary cultural identity of the West, and in some areas of the West that have the highest population growth in the US, urban development is taking place directly on top of limited agricultural land. In Boise, Idaho, the seventh-fastest growing metropolitan region in the US, urban land area has increased by 10% in just ten years (Narducci et al 2019). Urbanization is driven in large part by population influx from other regions of the country because of this region's affordability and high quality of life (Sharf 2018). At the same time, agriculture and food processing generates 21% of Idaho's total economic output, and the Boise metro area has some of the state's best agricultural land. Research indicates that most people in the Boise area are worried about the rate of farmland loss (Som Castellano et al 2017). However, the ability of communities to adapt, by implementing zoning, easements, or smart-growth, is constrained by a predominant conservative political ideology of limited government and private property rights. This ideology stems from antipathy to the one of the defining features of the West—federal land ownership—as 62% of the state of Idaho is owned by the federal government. With declines in agriculture and no complementary increase in conservation planning, ecosystem services provisioning is also shifting (for example, groundwater levels can drop with increased exurban residential water consumption as compared to that of agriculture) (Narducci et al 2019, Quintas-Soriano et al 2018).

Conflicts over how to manage vast portions of the West have dominated regional discourse since the late 19th century. More recent vacillations over federal monument designation in southern Utah—specifically the creation and subsequent reduction in size of Grand Staircase Escalante (GSENM) and BENMs—serve to illustrate key ongoing tensions that define the West generally. These include vast public land ownership and management versus local autonomy, environmental protection versus extraction, and changing economic opportunities versus cultural desire to maintain early colonialist economic activities—all set against a backdrop of sensitive ecosystems and a legacy of Native dispossession by federal and state governments (Spence 1999, Petrzelka and Marquart-Pyatt 2012). At their inception, GSENM and BENM were large protected area designations overlaid on federal lands previously managed for multiple use values (timber, mining, recreation, range, and ecological value such as wildlife habitat). Presidents designated the monuments (Clinton 1996, Obama 2016) to protect unique desert ecosystems and geologic features as well as Native cultural heritage. The National Monument boundaries are overlaid on a rural landscape with a strong history of extraction as the dominant livelihood. Today, the economy of some parts of the region is dominated by a service industry that caters to amenity migration and tourism, but recent reductions in monument size and scope by President Trump represent an attempt to reinvigorate an extractive industry (Headwaters Economics 2017).

Water management in the West often requires balancing diverse economic, ecological and cultural values with priorities for what is most often a scarce resource. The Henry's Fork of the Snake River sustains angling and agriculture, the two main industries in the region, as well as ecosystem health (Lawson 2012, Auerbach et al 2014). The regional economy is strongly tied to water resources, which annually produces approximately $2 billion (USD) in agriculture production and over $30 million (USD) from angling (Loomis 2006). Stakeholders within the Henry's Fork watershed have taken a collaborative approach to managing a scarce resource (Van Kirk and Griffin 1997, Van Kirk 2011, IDEQ 2017, Van Kirk et al 2019). Political, cultural and economic differences among those who use the watershed for agriculture, recreation and conservation could generate conflict. However, a shared cultural identity around the unique location and long history of angling in the river has provided a constructive starting point for collaborative decision-making in the watershed. Local non-profit organizations such as the Henry's Fork Foundation and the Friends of the Teton River dedicate their mission to preserving, protecting, and sustaining the biodiversity found in the river (Van Kirk et al 2019). These civil society groups have worked very closely with irrigation groups such as the Idaho Water Resource Board and the Henry's Fork Watershed Council to preserve the multifunctionality of the river. Consequently, ecological and agricultural groups and tourism industry have learned the best ways to share water resources so that all watershed stakeholders receive the benefits the Henry's Fork River provides (Van Kirk et al 2019).

The West is characterized by a history of colonial dispossession of indigenous lands, much of which has been incorporated into federal land management systems (Spence 1999). The loss of these lands has often led to the disenfranchisement of tribal and indigenous communities in setting goals for their shared management across jurisdictional boundaries. The Karuk Tribe, located in the Mid-Klamath region of California, is working to integrate traditional knowledge systems for managing forest ecosystems, including the use of prescribed fire to manage forest health, into priorities and partnerships with the US Forest Service and state agencies. Managing forest health using traditional practices also have the future-looking goal of reducing climate vulnerabilities associated with more frequent high intensity fires expected for the region (Norgaard 2016). This effort to maintain the viability of forest ecosystems and the non-timber forest products that are culturally and economically important provides an example of the social-ecological complexity associated with the political economy of tribal governance and public forest land management in the West. Global climate variability as an extra-regional driver of change in the Klamath region is expected to increase the severity of forest fires in the region and thus exacerbate coordination challenges across jurisdictions (Westerling et al 2006). It remains to be seen whether the traditional knowledge systems of the Karuk Tribe will be adequately integrated into future cross-jurisdictional approaches to forest and fire management and whether they are employed to reduce present and future vulnerabilities.