Fire has played an important role in the evolutionary environment of global ecosystems, and Indigenous peoples have long managed natural resources in these fire‐prone environments. We worked with the Navajo Nation Forestry Department to evaluate the historical role of fire on a 50 km2 landscape bisected by a natural mountain pass. We used fifty 5‐ha circular plots to collect proxy fire history data on fire‐scarred trees, stumps, logs, and snags in a coniferous forest centered on a key mountain pass. The fire history data were categorized into three groups: All (all 50 plots), Corridor (25 plots closest to Buffalo Pass drainage), and Outer (remaining 25 plots, farther from pass). We assessed spatial and temporal patterns of fire recurrence and fire‐climate relationships. The landscape experienced frequent fires from 1644, the earliest fire date with sufficient sample depth, to 1920, after which fire occurrence was interrupted. The mean fire interval (MFI) for fire dates scarring 10% or more of the samples was 6.25 years; there were 13 large‐scale fires identified with the 25% filter with an MFI of 22.6 years. Fire regimes varied over the landscape, with an early reduction in fire occurrence after 1829, likely associated with pastoralism, in the outer uplands away from the pass. In contrast, the pass corridor had continuing fire occurrence until the early 20th century.Synthesis. Fires were synchronized with large‐scale top‐down climatic oscillations (drought and La Niña), but the spatially explicit landscape sampling design allowed us to detect bottom‐up factors of topography, livestock grazing, and human movement patterns that interacted in complex ways to influence the fire regime at fine scales. Since the early 20th century, however, fires have been completely excluded. Fuel accumulation in the absence of fire and warming climate present challenges for future management.

Fire regimes in North American forests are diverse and modern fire records are often too short to capture important patterns, trends, feedbacks, and drivers of variability. Tree‐ring fire scars provide valuable perspectives on fire regimes, including centuries‐long records of fire year, season, frequency, severity, and size. Here, we introduce the newly compiled North American tree‐ring fire‐scar network (NAFSN), which contains 2562 sites, >37,000 fire‐scarred trees, and covers large parts of North America. We investigate the NAFSN in terms of geography, sample depth, vegetation, topography, climate, and human land use. Fire scars are found in most ecoregions, from boreal forests in northern Alaska and Canada to subtropical forests in southern Florida and Mexico. The network includes 91 tree species, but is dominated by gymnosperms in the genus Pinus. Fire scars are found from sea level to >4000‐m elevation and across a range of topographic settings that vary by ecoregion. Multiple regions are densely sampled (e.g., >1000 fire‐scarred trees), enabling new spatial analyses such as reconstructions of area burned. To demonstrate the potential of the network, we compared the climate space of the NAFSN to those of modern fires and forests; the NAFSN spans a climate space largely representative of the forested areas in North America, with notable gaps in warmer tropical climates. Modern fires are burning in similar climate spaces as historical fires, but disproportionately in warmer regions compared to the historical record, possibly related to under‐sampling of warm subtropical forests or supporting observations of changing fire regimes. The historical influence of Indigenous and non‐Indigenous human land use on fire regimes varies in space and time. A 20th century fire deficit associated with human activities is evident in many regions, yet fire regimes characterized by frequent surface fires are still active in some areas (e.g., Mexico and the southeastern United States). These analyses provide a foundation and framework for future studies using the hundreds of thousands of annually‐ to sub‐annually‐resolved tree‐ring records of fire spanning centuries, which will further advance our understanding of the interactions among fire, climate, topography, vegetation, and humans across North America.

Post-fire predictions of forest recovery under future climate change and management actions are necessary for forest managers to make decisions about treatments. We applied the Climate-Forest Vegetation Simulator (Climate-FVS), a new version of a widely used forest management model, to compare alternative climate and management scenarios in a severely burned multispecies forest of Arizona, USA. The incorporation of seven combinations of General Circulation Models (GCM) and emissions scenarios altered long-term (100 years) predictions of future forest condition compared to a No Climate Change (NCC) scenario, which forecast a gradual increase to high levels of forest density and carbon stock. In contrast, emissions scenarios that included continued high greenhouse gas releases led to near-complete deforestation by 2111. GCM-emissions scenario combinations that were less severe reduced forest structure and carbon stock relative to NCC. Fuel reduction treatments that had been applied prior to the severe wildfire did have persistent effects, especially under NCC, but were overwhelmed by increasingly severe climate change. We tested six management strategies aimed at sustaining future forests: prescribed burning at 5, 10, or 20-year intervals, thinning 40% or 60% of stand basal area, and no treatment. Severe climate change led to deforestation under all management regimes, but important differences emerged under the moderate scenarios: treatments that included regular prescribed burning fostered low density, wildfire-resistant forests composed of the naturally dominant species, ponderosa pine. Non-fire treatments under moderate climate change were forecast to become dense and susceptible to severe wildfire, with a shift to dominance by sprouting species. Current U.S. forest management requires modeling of future scenarios but does not mandate consideration of climate change effects. However, this study showed substantial differences in model outputs depending on climate and management actions. Managers should incorporate climate change into the process of analyzing the environmental effects of alternative actions.

Statistical descriptions of reconstructed fire regimes are often extrapolated from a composite of small forest stands to represent extensive geographical areas. However, statistical properties of fire regimes are scale‐dependent, thus causing some extrapolations from fine scale to coarse scale and comparisons between fire‐scar‐based reconstructions to be inappropriate. We assessed landscape fire regimes of the Sacramento Mountains, in southern New Mexico, using dendrochronological methods and a variety of fire statistics and analysis filters. We reconstructed historical and recent fire regimes for the Mescalero Apache Tribal Lands (MATL) at tree and site scale (25 ha). We then estimated the Sacramento Mountains historical and recent fire regimes by combining paleo fire data from this study with published data from the adjacent Lincoln National Forest (LNF). We applied filters to provide fire statistics that are relatively unbiased to the different spatial measurement extent of the studies. This is the first study to assess fire regime in the MATL over multiple spatial and temporal scales. The results show that frequent surface fires occurred at all scales in the Sacramento Mountains until fire was excluded from the landscape in the early 1900s. Historical fires were found to be synchronous with drought years, typically La Niña events, and often preceded by wet years. We did not find evidence supporting differences in fire regimes between the MATL and the LNF, suggesting that fire cessation following intensive Euro‐American settlement was widespread. The interruption of frequent surface fires, together with other changes in forest structure and climate, pose a significant threat to sustainability of forest ecosystems on Native American tribal lands.

The Mescalero Apache Tribal Lands (MATL) provide a diverse range of ecosystem services, many of which are of fundamental importance for the Mescalero Apache Tribe’s well-being. Managing forests on MATL, especially under climate change, involves prioritizing certain ecosystem services. We used an iterative survey of experts’ opinions to identify those ecosystem services that 1) have high utility—services that the Tribe uses, or could use, and are obtained directly or indirectly from the MATL; 2) are irreplaceable—services that cannot be provided by any other natural resource; and 3) are under a high level of threat—services at risk of declining or being lost directly or indirectly by climate change and thus are critical for management. Both scientists and practitioners identified water and cultural services as management priorities. Management recommendations to mitigate and adapt to climate change effects include reintroduction of fire in the landscape, assisted migration, creation of age/size mosaics across the landscape, and incorporation of green energy. Incorporating human perspectives into natural resource management is a critical component to maintain and adapt social–ecological systems to climate change, especially for Indigenous communities with inherent rights of sovereignty who are deeply connected to natural resources. This study demonstrates how knowledge systems are complementary: diverse perspectives related to values and threats of ecosystems can be incorporated to coconstruct ecosystem management decisions.