Changing land and people across the high divide : a land use transition analysis

The rangelands in the American West are changing as part of an ongoing land use transition. Exurban development in very rural places continues to expand, as ranching and managed livestock grazing declines. Traditional rural residents are frequent neighbors to telecommuting amenity migrants and urban recreationists, leading to new social interactions and intensified conflicts in rural spaces. There is widespread concern over the loss and fragmentation of rangeland habitat due to exurban development, but the ecological consequences of changing livestock grazing regimes is uncertain. One response to multi-faceted rural change in the American West has been the emergence of collaborative processes that bring multiple stakeholders together to maintain working landscapes, but the possibility of these approaches to resolve conflicts and guide rural transitions is still being tested. What are the drivers of a multi-faceted land use transitions on rangelands and what do the impacts and responses to those transitions mean for the future of rural spaces and ecologies? This dissertation sought to answer this motivating question by looking closely at the land use transition in one region of the American West—the High Divide in the Northern Rocky Mountains. Utilizing a social-ecological systems approach, I investigated the drivers, ecological impacts, and social responses to changes on rangelands. The second chapter of this dissertation asks how and why public lands grazing has changed on two National Forests in Idaho's High Divide. While the existing literature identifies broad-scale drivers of change on rangelands, few studies have looked closely at how livestock grazing has changed at regional scales and tied those changes to specific multi-level drivers. I created a spatially explicit grazing history since 1940 through a detailed analysis of United States Forest Service (USFS) management records. I used the full suite of records to qualitatively process-trace the proximate causes of changes in grazing and identify the decision-makers, and quantitatively tested which underlying factors were associated with changes in grazing. The forage annually consumed by livestock in our study area declined by 62% since 1940, the equivalent of about 33,000 fewer cows grazing on public lands for a three-month summer period. Livestock grazing was closed on 21% of the total study area. The reductions in grazing were mainly caused by land management and policy factors: evaluations of range condition (27%), carrying capacity estimates (21%) and legal and administrative requirements (14%) derived from the Endangered Species Act (ESA) and National Environmental Protection Act (NEPA). The socio-economic causes of ranch economics (14%) and amenity migration (8%) were comparatively small. Overlap with wilderness and proximity to amenity towns were significant spatial predictors of reductions in grazing. The research highlights that the fate of publicly-owned but privately-used rangelands largely depends on institutions that can reconcile the competing demands on these lands. In the third chapter, I investigated how changes in grazing regimes are impacting conifer encroachment into rangelands using a natural experiment design and image analysis of very high-resolution aerial photos. The dynamic interface between forest and rangelands is an important facet of global change, and many factors simultaneously drive shifts over time. In the drylands of the American West, forests and rangelands are both under pressure as past histories of land use and fire suppression collide with increasing incidence of drought, catastrophic wildfire, and disease pressure due to climate change. This research is the most comprehensive investigation of conifer cover change in the Northern Rocky Mountains to date. I employed a novel research design that contributes to the ecological literature on woody plant encroachment more broadly. Despite losses due to fire, net conifer cover increased by 13% since 1955. Contrary to a widely held view, reduction in stocking rates of livestock did not drive conifer encroachment. Changing from sheep to cattle grazing between 40 and 70 years ago was associated with increased conifer cover. Fire was the most significant driver of conifer cover change in the landscape, with recent fire driving forest loss and older fires driving forest expansion. Finally, in the fourth chapter, I present a single case study of collaboration in a public forest planning context facing social and political polarization in the High Divide. Using participant observation, semi-structured interviews, and document review, I identify trade-offs and discuss lessons that inform the design and implementation of collaborative governance regimes. Collaborative governance has proliferated as a strategy to engage stakeholders in the complexity of environmental problems. However, collaboration has limitations and increasing polarization in many places could impact the ability to bring diverse stakeholders together. The case highlights the vulnerability of local collaboration to political shifts at other scales of government, but also shows how key collaboration dynamics related to facilitation, structure, representation, and shared learning interact with a polarized context to impact the trajectory of collaborative governance regimes

Advisor: Anderson Michelle
Lambin Eric F.
Huntsinger Lynn