Evaluating trade-offs of hazardous fuel reduction in Navajo Nation woodlands

Abstract Background Pinyon-juniper woodlands are increasingly vulnerable to severe wildfires due to altered fire regimes, fuel accumulation, and the decline of traditional Indigenous management practices. On the Navajo Nation, where these woodlands hold both ecological and cultural significance, evaluating the effectiveness of fuel reduction treatments is essential for adaptive fire management. Results We experimented with thinning a persistent woodland and utilized the Fire and Fuels Extension (FFE) of the Forest Vegetation Simulator (FVS) to model fire behavior after thinning with a diameter cap of 25 cm, as well as two simulated thinning scenarios with diameter caps 35 cm and 50 cm. All treatments reduced crown fire potential and canopy fuel loss to varying degrees; however, the least intensive treatment (25 cm) left stand densities sufficient to support crown fire under severe weather conditions. Conclusions The findings underscore the need to strike a balance between fuel treatments and ecological and cultural priorities. Low-intensity thinning retains culturally relevant structure and old-growth characteristics but may fail under severe fire weather conditions. More intensive treatments (35 and 50 cm) substantially reduced fire behavior metrics but introduced trade-offs. Although the 25-cm diameter cap was based on ecological research, observations from community members about dense woodlands and sparse understory highlight the need for treatment mosaics that take culturally important trees and areas into consideration. Increased thinning intensity may be valuable in areas with high values-at-risk, such as the wildland-urban interface, to mitigate crown fire potential and protect communities. Managers could use the range of thinning treatments tested to create a strategic mosaic of fuel reduction across the landscape. This study offers critical insight into the trade-offs associated with restoration and fuel treatment strategies in culturally and ecologically important woodlands.