Insights into the restoration and sustainable management of Emory oak: A southwestern cultural keystone species

Abstract Emory oak acorns are a critically important commodity for Western Apache Tribal Nations, both as a food source and also for cultural and ceremonial uses. The Apache people historically inhabited much of Emory oak's range, but these lands are now divided among many entities, with the majority of trees occurring off-reservation in public domains. Based on observations of diminished acorn production and seedling recruitment, Apache Elders called for restoration and improved management of Emory oaks on public lands to ensure the long-term availability of acorns for Western Apache Tribes. Ecological information is critical to effectively design restoration efforts and successfully manage Emory oak, but little is known about Emory oak’s current ecological status on the landscape. Here, we use Forest Inventory and Analysis (FIA) data to examine factors that influence Emory oak distribution, abundance, and demography, and relate findings to observations made by Tribal Elders. We found that Emory oak distribution was constrained by metrics related to water availability. Drought and fire occurred frequently in Emory oak habitats, highlighting the likely importance of these disturbance events in determining oak population dynamics. Emory oak growth was predicted by environmental variables related to water availability, like physiographic class and elevation, and population characteristics, like stand age and size, but not by land ownership classifications. Interestingly, no environmental variables explained patterns of seedling recruitment and mortality perhaps owing to the stochastic nature of these events and the coarse temporal scale of FIA data in AZ. Drier, warmer conditions projected by climate models was shown to reduce future suitable Emory oak habitat, particularly in central AZ. Restoration efforts should focus on increasing water availability for Emory oaks and reducing the likelihood of high intensity fires. This could be accomplished, in part, by thinning competing vegetation at Emory oaks stands and restoring historical fire regimes. Given projections that suggest drier regional climatic patterns, strategic seed augmentation aimed at enhancing population resilience through selection of drought-adapted genotypes may also be warranted. Data were insufficient to confirm Apache Elders’ observations of diminished acorn production and seedling recruitment, highlighting the need for comprehensive demographic analyses of Emory oaks in the Southwest.