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Tribal communities in the Pacific Northwest of the United States of America (USA) have long-standing relationships to ancestral lands now managed by federal land management agencies. In recent decades, federal and state governments have increasingly recognized tribal rights to resources on public lands and to participate in their management. In support of a new planning initiative to promote sustainable land management, we reviewed scientific publications to examine relationships between tribal social-ecological systems and public lands in the region. We identified key ecocultural resources, impacts to those resources, and associated forest ecosystems, and strategies that have been piloted to redress those impacts. We found that many factors stemming from colonization by Euro-Americans have engendered social-ecological traps that have inhibited tribes from continuing traditional land stewardship activities that supported their well-being and maintained ecological integrity. These long-standing factors include legal and political constraints on tribal access and management; declining quality and abundance of forest resources due to inhibition of both natural disturbance and indigenous tending regimes; competition with nontribal users; species extirpations and introductions of invasive species; and erosion of tribal traditional ecological knowledge and relationships that are important for revitalizing resource use. As a consequence, both supply and demand for these forest resources have been reduced, as have the resilience and diversity of these ecosystems. Simply permitting resource harvest by tribal members does not sufficiently address the underlying constraints in ways that will promote tribal well-being. Escaping these traps will require addressing a gamut of ecological and social constraints through cooperative restoration efforts between land management agencies and tribes, several of which we highlight as examples. Because tribally focused restoration strategies generally align with broader strategies suggested to restore national forests in the region, they can foster both tribal well-being and ecological sustainability.

Climate change will accelerate forest mortality due to insects, disease, and wildfire. As a result, substantial resources will be necessary where and when forest managers seek to maintain multiple management objectives. Because of the increasing managerial requirements to offset climate change and related disturbances, the uncertainty about future forest conditions is magnified relative to climate change alone. We provide an analytical approach that quantifies the key drivers of forest change—climate, disturbance, and forest management—using scenarios paired with simulation modeling to forecast and quantify uncertainties in the Lake Tahoe Basin of California and Nevada (USA), a montane seasonally dry conifer forest. We partitioned uncertainty among climate change (including associated changes to wildfire and insect outbreaks), forest management (including thinning, prescribed fire, and fire suppression), and other sources using a fully factorial experimental design and analysis of variance. We focused on three metrics that are important for forest management objectives for the area: forest carbon storage, area burned at high severity, and total area burned by wildfire. Management explained a substantial amount of variance in the short term for area burned at high severity and longer term carbon storage, while climate explained the most variance in total area burned. Our results suggest that simulated extensive management activities will not meet all the desired management objectives. Both the extent and intensity of forest management will need to increase significantly to keep pace with predicted climate and wildfire conditions.

Forest managers working in dry forest ecosystems must contend with the costs and benefits of fire, and they are seeking forest management strategies that enhance the resilience of forests and landscapes to future disturbances in a changing climate. An interdisciplinary science team worked with resource managers and stakeholders to assess future forest ecosystem dynamics, given potential climatic changes and management strategies, across a 23,000-ha landscape in the Lake Tahoe basin of California and Nevada in support of the Lake Tahoe West Restoration Partnership. We projected forest growth and fire dynamics using a landscape change model, upon which the science team layered additional modeling to evaluate changes in wildlife habitat, water, and economics. Managers and stakeholders used the findings of this integrated modeling effort to inform the design of a landscape restoration strategy that balanced risks and benefits based on a robust scientific foundation. The results, published in this Special Feature, suggest that a continuation of status quo management would be less effective at protecting and improving desired outcomes than more active and extensive management approaches. In addition, the types of management activity also affected ecosystem outcomes. Results from across the studies in this special feature suggest that thinning and prescribed fire were complementary, although they resulted in somewhat different effects, and that low-severity use of fire had the greatest array and magnitude of ecosystem benefits. A notable exception was carbon storage, which declined with more active management and prescribed fire in particular. We highlight key findings from this Special Feature and summarize key challenges and some lessons learned in our experience of co-producing science. In short, science-management partnerships require cooperation, patience, and skill, but they are effective in increasing the capacity of land managers to navigate in an environment of rapid change and increasing uncertainty.

Because of past land use changes and changing climate, forests are moving outside of their historical range of variation. As fires become more severe, forest managers are searching for strategies that can restore forest health and reduce fire risk. However, management activities are only one part of a suite of disturbance vectors that shape forest conditions. To account for the range of disturbance intensities and disturbance types (wildfire, bark beetles, and management), we developed a disturbance return interval (DRI) that represents the average return period for any disturbance, human or natural. We applied the DRI to examine forest change in the Lake Tahoe Basin of California and Nevada. We specifically investigated the consequences of DRI on the proportion of high-severity fire and the net sequestration of carbon. In order to test the management component of the DRI, we developed management scenarios with forest managers and stakeholders in the region; these scenarios were integrated into a mechanistic forest landscape model that also accounted for climate change, as well as natural disturbances of wildfire and insect outbreaks. Our results suggest increasing the frequency of disturbances (a lower DRI) would reduce the percentage of high-severity fire on landscape but not the total amount of wildfire in general. However, a higher DRI reduced carbon storage and sequestration, particularly in management strategies that emphasized prescribed fire over hand or mechanical fuel treatments.

Smoke from wildfires has become a growing public health issue around the world but especially in western North America and California. At the same time, managers and scientists recommend thinning and intentional use of wildland fires to restore forest health and reduce smoke from poorly controlled wildfires. Because of the changing climate and management paradigms, the evaluation of smoke impacts needs to shift evaluations from the scale of individual fire events to long-term fire regimes and regional impacts under different management strategies. To confront this challenge, we integrated three widely used modeling tools to analyze smoke impacts across different management scenarios within a future of changing climate. We applied this multi-stage framework to a case study analysis in the Lake Tahoe basin, in which managers proposed scenarios that involved varying levels of hand- and mechanical-thinning treatments and prescribed fires. We began by using the LANDIS-II model to project daily emissions of fine particulate matter from wildland fires under various climate and management scenarios over a century. We also modeled dispersion and health impacts based upon individual wildfire events selected to be representative of different management scenarios. For those events, we modeled smoke conveyance to downwind communities from representative future fires using the BlueSky smoke dispersion model. Lastly, we estimated human health impacts resulting from the modeled smoke using the U.S. Environmental Protection Agency's BenMAP model. Our results suggest that emissions from wildfires will substantially increase in future decades; however, increased levels of forest thinning could substantially reduce those emissions and harmful health impacts from large wildfires. We also found that increased use of prescribed burning could reduce the health impacts associated with large wildfires but would also increase the frequency of low levels of emissions. Furthermore, the modeling results suggested that individual prescribed fires could have substantial health impacts if dispersion conditions are unfavorable. Our results suggest that increased management is likely to yield important benefits given expected increases in wildfire activity associated with climate change. However, there remain many challenges to projecting the effects of alternative management regimes, especially ones that involve substantial increases in intentional burning.

Rapid environmental changes challenge the resilience of wildlands. The western portion of the Lake Tahoe Basin in California is an important ecological and cultural hotspot that is at risk of degradation from current and future environmental pressures. Historical uses, fire suppression, and a changing climate have created forest landscape conditions at risk of drought stress, destructive fire, and loss of habitat diversity. We prospectively modeled forest landscape conditions for a period of 100 years to evaluate the efficacy of 5 unique management scenarios in achieving desired landscape conditions. Management scenarios ranged from no management other than fire suppression to applying treatments consistent with historical fire frequencies and extent (i.e., regular and broadscale biomass reduction). We developed a decision support tool to evaluate environmental and social outcomes within a single framework to provide a transparent set of costs and benefits. Results illuminated underlying mechanisms of forest resilience and provided actionable guidance to decision makers. Sixteen attributes were assessed in the model after assigning weights to each. We found that removing forest biomass across the landscape, particularly when accomplished using extensive fire-based removal techniques, led to highly favorable conditions for environmental quality and promoted overall landscape resilience. Environmental conditions resulting from extensive fire-based biomass removal also had nominal variation over time, in contrast with strategies that had less extensive and/or used physical removal techniques (e.g., mechanical thinning). Our analysis provides a transparent approach to assess large datasets with complex and interacting variables. Ultimately, we aim to provide insights into the complexities of maintaining optimal conditions and managing landscapes to promote ecosystem resilience in a changing world.

Wildfires play an important ecological role in fire-adapted landscapes throughout California. However, there is a growing awareness that large wildfires in increasingly populated areas incur costs that may not be acceptable to society. Various forest management strategies have been proposed that seek to reduce the prevalence and severity of wildfires in areas where these costs are high. In this study we estimate the financial costs of various hypothetical forest management scenarios in the Lake Tahoe West landscape of Northern California. The objective of the study was to quantify trade-offs and cost constraints that would affect the feasibility of each scenario. The scenarios ranged from minimal forest management to several options for more intensive fuels management that relied to varying degrees on thinning and prescribed burning. We assessed stand-level costs associated with thinning, prescribed burn management, and timber and biomass transport, as well as revenues from timber and energy chips sold. Using modeled fire occurrence and severity metrics, we also used historical wildfire data to estimate plausible fire suppression costs. Our findings suggest that increased forest management, through the use of either hand/mechanical treatments or prescribed fire, can reduce fire suppression costs relative to recent practices by more than US$400,000 per year. These more intensive management scenarios differ in their cost-effectiveness. Scenarios that increase the use of prescribed fire appear to be the more cost-effective management interventions available with annual costs roughly half as much as a scenario focused on increased hand and mechanical thinning. The results are useful for understanding the financial implications of modifying forest management practices designed to lower the private and social costs of wildfire in the region.

Across the United States, wildfire severity and frequency are increasing, placing many properties at risk of harm or destruction. We quantify and compare how different forest management strategies designed to increase forest resilience and health reduce the number of properties at risk from wildfire, focusing on the Lake Tahoe Basin of California and Nevada. We combine landscape change simulations (including climate change, wildfire, and management effects) with scenarios of current and plausible fuel treatment activities and parcel-scale fire risk analysis. Results suggest that more aggressive fuel treatment activities that treat more area on the landscape, whether through mechanical and hand thinning or prescribed fire, dramatically lower the fire probability in the region and lead to a corresponding lower risk of property loss. We estimate that relative to recent practices of focusing management in the wildland–urban interface, more active forest management can reduce property loss risk by 45%–76%, or approximately 2600–4900 properties. The majority of this risk reduction is for single family residences, which constitute most structures in the region. Further, we find that the highest risk reduction is obtained through strategies that treat a substantially greater area than is currently treated in the region and allows for selective wildfires to burn for resource objectives outside of the wildland–urban interface. These results highlight the importance of more active forest management as an effective tool in reducing the wildfire risk to capital assets in the region.

Wildfires in many western North American forests are becoming more frequent, larger, and severe, with changed seasonal patterns. In response, coniferous forest ecosystems will transition toward dominance by fire‐adapted hardwoods, shrubs, meadows, and grasslands, which may benefit some faunal communities, but not others. We describe factors that limit and promote faunal resilience to shifting wildfire regimes for terrestrial and aquatic ecosystems. We highlight the potential value of interspersed nonforest patches to terrestrial wildlife. Similarly, we review watershed thresholds and factors that control the resilience of aquatic ecosystems to wildfire, mediated by thermal changes and chemical, debris, and sediment loadings. We present a 2‐dimensional life history framework to describe temporal and spatial life history traits that species use to resist wildfire effects or to recover after wildfire disturbance at a metapopulation scale. The role of fire refuge is explored for metapopulations of species. In aquatic systems, recovery of assemblages postfire may be faster for smaller fires where unburned tributary basins or instream structures provide refuge from debris and sediment flows. We envision that more‐frequent, lower‐severity fires will favor opportunistic species and that less‐frequent high‐severity fires will favor better competitors. Along the spatial dimension, we hypothesize that fire regimes that are predictable and generate burned patches in close proximity to refuge will favor species that move to refuges and later recolonize, whereas fire regimes that tend to generate less‐severely burned patches may favor species that shelter in place. Looking beyond the trees to forest fauna, we consider mitigation options to enhance resilience and buy time for species facing a no‐analog future. Wildfires in many western North American forests are becoming more frequent, larger, and more severe due to changes in climate and past fire suppression. We propose a new life history framework for wildlife response to frequency, intensity, and patch size of wildfire disturbances. Finally, we consider forest management strategies that might enhance the resilience of wildlife under transient future conditions.

Land managers in the Lake Tahoe basin are considering increasing the use of prescribed fire and forest thinning to restore conditions that will be more resilient to wildfires. However, such restorative treatments also constitute disturbances that could increase sediment and nutrient loads. We examined whether the water-quality impacts from future treatments are likely to be lower compared to the potential impacts from future wildfires under various climate change scenarios. We applied an online interface for the Water Erosion Prediction Project (WEPP) model in combination with a landscape change model (LANDIS-II) to evaluate the effects of different combinations of thinning and prescribed burning on fine sediment (< 2 mm), very fine sediment (< 16 µm), and phosphorus over time. First, we generated results based on historic weather data for soil disturbance conditions, including: an undisturbed baseline, a uniform thinning treatment; a uniform prescribed fire treatment; and uniform low, moderate, and high wildfire burn severity. Residual ground cover declined in that order, and expected loads of sediment and phosphorus increased. We then combined the estimated loads from hillslopes with projected management-disturbance regimes across each decade of the next century. We found that expected sediment and phosphorus loads were lower under the scenario that emphasized thinning, whereas scenarios that increased prescribed burning resulted in loads that were comparable to scenarios that involved less treatment. These results reflect the finding from the WEPP analysis that prescribed burning is expected to reduce ground cover more than is thinning. Our analysis supports efforts to increase fuel reduction treatments to mitigate future wildfires, but it also suggests that preventative treatments may not avoid a long-term decline in water quality as wildfires increase with climate change.