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Title: Exploring the Drivers of Western Juniper Expansion in a Southwestern Idaho Watershed.
Abstract: Since the mid-1800s, western juniper (Juniperus occidentalis) has expanded into sagebrush steppe communities across southwestern Idaho, Washington, and Oregon, triggering shifts in habitat dynamics. Climate change in the Pacific Northwest is expected to increase annual temperatures and decrease precipitation. This shift is likely to promote expansion of juniper due to their extensive root systems that outcompete those of native shrub and herbaceous vegetation. Expansion of juniper raises concerns about potential impacts on biodiversity and ecosystem processes. Active studies of western juniper expansion are finding that juniper expansion can disrupt hydrologic cycles, plant regimes, and wildlife habitat. However, few studies have investigated the cause of juniper expansion; determining causality is key for determining management solutions from stakeholders. This study evaluates the impact of climate change and other primary disturbance factors (e.g., land management/land use and fire occurrence) on the expansion of juniper within a southwestern Idaho watershed, which is essential for improving present and future management of shrubland ecosystems. The primary goals of this study are to 1) map and date juniper to produce a disturbance map delineating the expansion of western juniper in the Reynolds Creek Experimental Watershed in SW Idaho; 2) understand the influence of anthropogenic climate change, fire occurrence, and land management/land use disturbance effects on juniper expansion and 3) translate that information into user-ready materials that can help develop long-term management plans for western juniper expansion into sagebrush steppe. By identifying past critical thresholds of western juniper expansion, land managers can optimize resource allocations, potentially reducing cost of future management. The conserved resources can then be directed towards initiatives aimed at assisting sagebrush steppe ecosystems in adapting to current and future disturbances. Insight gleaned from our research concerning the drivers of juniper expansion will inform efficient management solutions of sagebrush steppe communities in RCEW and across the northern Great Basin more broadly.
Advisors: Jen Pierce, Megan Cattau
Committee:Â David Wilkins, David Huber
Zoom Link: https://boisestate.zoom.us/j/99750183160