Ecological partnership: Restoring Pinyon woodlands on the Navajo Nation, USA

Abstract

Pinyon woodlands in the semi-arid southwestern United States developed in response to environmental factors and historical human interactions, providing sustenance and traditional ecological benefits to Native Nations, such as the Navajo (Diné). Historically, Diné communities practiced land stewardship through seasonal movements and resource management, ensuring ecosystem resilience. However, the constraints imposed by European colonization led to transformative changes in their livelihoods and environments. Encompassing 71,000 km², pinyon-juniper woodlands comprise 89 % of forested area on the Navajo Nation reservation, providing crucial ecosystem services and cultural resources. Since reservation establishment in 1868, increased tree density has diminished understory plant communities and elevated woodland susceptibility to wildfires, compromising overall forest health. Recognizing the imperative for ecological restoration, a collaborative effort between Diné College and Northern Arizona University (NAU) was established in 2018 to develop a pinyon woodland research site on the Diné College campus in Tsaile, Arizona, on the Navajo Nation reservation. We assessed the effectiveness of restoration thinning treatments in reinstating historical woodland structure, modifying fuels for fire mitigation, and engaging students in ecological practices. Thinning resulted in a 62 % reduction in tree density and a 25 % reduction in basal area, altering the woodland structure to reflect historical conditions more accurately. This alteration mitigated the risk of high-intensity wildfires while preserving the age structure of older trees (oldest dating back to 1435 C.E.). Forest floor fuels were low throughout the study, as thinned wood was removed, and activity fuels were immediately treated with chipping. The active participation of Diné College and NAU students, interns, and faculty throughout the study contributed to a cohesive approach in advancing our goals. The comprehensive training empowered students to contribute meaningfully to fieldwork and data collection, aligning with Diné College's mission to enhance post-secondary student learning and development for the benefit of the Diné. By integrating contemporary and culturally sensitive perspectives, our study sheds light on the effectiveness of restoration thinning treatments, emphasizing the delicate balance between ecological resilience and cultural preservation for the Navajo Nation.