US National Forests Research Articles

Modernizing the US National Fire Danger Rating System (version 4): Simplified fuel models and improved live and dead fuel moisture calculations

The US National Fire Danger Rating System (USNFDRS) supports wildfire management decisions nationwide, but it has not been updated since 1988. Here we implement new fuel moisture models, and we simplify the fuel models while maintaining the overall USNFDRS structure. Modeled and measured live fuel moisture content values were highly correlated (r2=0.629 with defaults and r2=0.693 when species and location optimized). We also consolidated fuel models to five fuel types that eliminated significant index cross-correlation. Index seasonality compared between old (V2) and new USNFDRS models (v4) across six US National Forests was very similar (ρ= 0.97). V4 was as good or better than V2 at predicting fire days in 92% of the cases tested and V4 effectively predicted wildfire days and large fire ignition days (AUCs 0.647 to 0.915). USNFDRS V4 can adequately depict spatial and temporal wildland fire potential and it can be adapted for worldwide use.

Southern Alaska's Forest Landscape Integrity, Habitat, and Carbon Are Critical for Meeting Climate and Conservation Goals

AbstractThe interdependent crises of climate change and biodiversity losses require strategic policies to protect, manage, and restore essential ecosystems. Here, we evaluate the relative importance of US national forests (NFs) for protection and conservation as natural climate and biodiversity solutions. We compared landscape integrity (degree of modification by humans), habitat for three keystone species, forest carbon density, accumulation, and total biomass carbon stocks across 154 NFs in the United States. Southern Alaska's Tongass and Chugach NFs hold disproportionally large amounts of high landscape integrity area among all NFs with 25.3% and 5.6% (total 30.9%) of all high (≥9.6) landscape integrity found on NF lands. The Tongass and Chugach store approximately 33% and 3% of all biomass carbon stocks that occur in NFs with high landscape integrity. These two NFs together account for about 49%, 37%, and 18% of all bald eagle, brown bear, and gray wolf habitat found on NF lands. Gray wolf habitat extent was 4% of the total or less on remaining NFs. The Tongass and Chugach were historically wetter and cooler among NFs, and are projected to experience much larger increases in precipitation and much lower increases in maximum temperatures over the coming century. Combined with relatively low recent occurrence of wildfire, this makes permanence more likely. The Tongass and Chugach forests, along with the Pacific Northwest's high carbon density forests should be a high priority for protection and conservation to meet climate and biodiversity goals given their landscape‐scale scarcity and high value.

Quantifying old-growth forest of United States Forest Service public lands

Old-growth forests are globally valued for their ecological attributes, cultural significance, and in many cases their rarity. Yet, defining and quantifying these forests has been a difficult task. This study developed an approach to consistently estimate extent of old-growth forest on United States Department of Agriculture (USDA) Forest Service National Forest System (NFS) lands, using NFS regional old-growth definitions applied to the US national forest inventory (conducted by the USDA Forest Service Forest Inventory and Analysis [FIA] program). This method was developed in response to a presidential order (EO#14072, April 22, 2022) and federal laws (e.g., Infrastructure Investment and Jobs Act, 2021; Inflation Reduction Act, 2022). We worked with NFS experts to obtain regionally approved criteria for establishing old growth status based on NFS definitions, assessments, and related documents. NFS regional old growth definitions focus on structural characteristics of forests with criteria for old growth status commonly including minimum abundance of large live trees (in eight of nine regions), tree or stand age (in eight of nine regions), and dead large tree density (in three of nine regions). Determining the regional criteria to use was straightforward for some NFS regions where old-growth forest definitions were specific, and in some cases, had already been applied to FIA data to quantify old-growth forest area. In other NFS regions, such as where definitions have never been applied in an operational manner, or where there were merely assessments of remnant old-growth forest conditions, determining exact criteria was more difficult. We estimate that there are approximately 10 million ha of old growth across NFS forests, as defined by NFS criteria, with the preponderance in the western US states. This study produces the first old-growth forest assessment at the national scale based on NFS definitions and FIA’s statistically-rigorous national forest inventory of the US. These methods can be repeated with future inventories or modified when definitions change to produce updated estimates of old-growth forest attributes, and such work is already underway.

Standardized naming convention and classification system for critical loads of nitrogen and sulfur deposition

AbstractCritical loads (CLs) of atmospheric deposition have been used for multiple decades to assess the impacts of air pollutants on terrestrial and aquatic ecosystems. However, these CLs have been developed by different researchers, at different times, using different methods, and are named in different ways with varying levels of information and levels of specificity. In this study, we identified the elements that describe CLs and used them to develop and test a standardized CL naming convention and a complementary CL classification system applicable to all CLs. The CL naming convention consists of: the form of deposition; the biological receptor, response, and threshold; and chemical criterion and threshold, thereby clearly communicating what the CL is and what it protects. The CL classification system contains all the elements that define and describe a CL, but the CL classes are not fixed and are therefore, defined by the user. The application of the CL naming convention and classification system to an existing US CL database and national forest was successful, demonstrating not only the utility of the naming convention and classification system, but how both can also be used to guide future CL science.

Sustainability Language in Forest Management Plans: A Comparative Analysis for Public Forests of the US and Turkey

Forest management plans often suggest that economic, ecological, and/or social sustainability will be achieved if the proposed management actions are followed. Using forest plans developed by the US Department of Agriculture Forest Service and the Republic of Turkey, the purposes of this study were to (i) extract those statements that suggest sustainability will be achieved and (ii) assess whether there exist statistical differences between the two countries’ plans and the emphases of the findings. A content analysis and non-parametric statistical tests were employed to measure the frequency of a set of terms related to sustainability and to estimate significant differences in the use of sustainability terms in the plans sampled. Results suggest that ecological aspects are dominant in forest plans from both countries. While silviculture, sustained yield, and multiple use were the most frequently used terms in Turkish plans, the occurrences of conservation and recreation were significantly higher in US plans (p < 0.001). These findings suggest that the differences in the plans’ emphases could be attributable to the importance of Turkey’s forests for the wood production-related needs of Turkish society, whereas US national forests might no longer be seen as an important wood supply base but instead have been given a more “passive” forest use.

Multi-Objective Scheduling of Fuel Treatments to Implement a Linear Fuel Break Network

We developed and applied a spatial optimization algorithm to prioritize forest and fuel management treatments within a proposed linear fuel break network on a 0.5 million ha Western US national forest. The large fuel break network, combined with the logistics of conducting forest and fuel management, requires that treatments be partitioned into a sequence of discrete projects, individually implemented over the next 10–20 years. The original plan for the network did not consider how linear segments would be packaged into projects and how projects would be prioritized for treatments over time, as the network is constructed. Using our optimization algorithm, we analyzed 13 implementation scenarios where size-constrained projects were prioritized based on predicted wildfire hazard, treatment costs, and harvest revenues. We found that among the scenarios, the predicted net revenue ranged from USD 3495 to USD 6642 ha−1, and that prioritizing the wildfire encounter rate reduced the net revenue and harvested timber. We demonstrate how the tradeoffs could be minimized using a multi-objective optimization approach. We found that the most efficient implementation scale was a sequence of relatively small projects that treated 300 ha ± 10% versus larger projects with a larger treated area. Our study demonstrates a decision support model for multi-objective optimization to implement large fuel break networks such as those being proposed or implemented in many fire-prone regions around the globe.

Designing forest restoration projects to optimize the application of broadcast burning

Active forest restoration programs on western US national forests face multiple challenges to meet their broad ecological goals while designing projects that generate sufficient revenue to build and maintain private forest management capacity needed to expand the scale and scope of treatments. We explored ways to design projects where admixing of treatments along gradients of dry and moist mixed conifer forest types could maximize financial viability while including substantial area where broadcast burning could be applied in conjunction with other treatments. In general, we found that restoration treatments in dry forests that included density reduction thinning and broadcast burning resulted in a net projected cost ranging from $110 to $8000 per ha. By contrast, density reduction thinning in moist mixed conifer forests on more productive microsites generated significant commercial timber volume and projected revenue that ranged from $4000 to $20,000 per ha. We used spatial optimization methods to identify potential project areas that maximized revenue while meeting constraints to treat a minimum proportion of each project with broadcast burning. Multiple project area sizes were also explored to understand the effect of restoration scale on financial outcomes. We found that optimal projects in terms of generating revenue to subsidize density reduction and broadcast burning were 810 ha and contained >50% dry forest area. Larger projects and those with a higher percentage of dry forest area resulted in lower revenue, eliminating revenue when projects reached 2700 ha. Forest restoration programs can use these methods to plan and design restoration projects that are financially viable while addressing the broadcast burn backlog in dry forests that require relatively expensive fuel reduction treatments prior to re-introducing fire.

Development of a framework for understanding unsold timber offerings from the US National Forest System

Timber sales from the US National Forest System (NFS) can provide ecological and economic benefits. Unsold (“no-bid”) offerings can result in delays, additional costs, and missed targets. We used mixed methods, including analysis of administrative data, synthesis of research, and semi-structured interviews to understand situations considered “no-bid” offerings by different stakeholders. We measured prevalence, identified causes, and generated a framework for communicating interlinkages. From 2007 to 2020, the volume not sold at first offering was 11.9% nationally. However, a substantial amount is sold subsequently, leaving 2.7% never sold. Regions with the highest percentage never sold include Alaska, Southwestern, and Pacific Southwest. A new conceptual framework developed from a literature review and interviews with NFS and industry employees identified proximate causes and underlying factors. Proximate causes include road construction, equipment requirements, and timber condition; whereas underlying factors include staffing, communication, and appraisal methods. These insights can aid communication and help develop future strategies.

Estimating maximum stand density for mixed-hardwood forests among various physiographic zones in the eastern US

Quantifying maximum stand density is important to evaluate the potential stand density of the target population in forest management. However, most of the past research in the eastern US was mainly focused on planted monocultures, coniferous forests, a few commercially important species at the stand level, or in a particular geographic region. This study aimed to estimate the maximum stand density for mixed-hardwood forests across physiographic zones in the eastern US between two decades (1996–2009 and 2010–2021). Data used in analyses were collected from the US national forest inventory established and maintained by the USDA Forest Service’s Forest Inventory and Analysis (FIA) program.Results showed that the slope of the self-thinning lines varied among forest types. Estimating maximum stand density index (SDImax) from size-density relationships produced more precise estimates than using SDI-size curves. Among all forest types, elm-ash-cottonwood (Ulmus-Fraxinus-Populus) showed consistent SDImax estimates whereas other forest types varied by regions. New England had considerably higher SDImax in aspen-birch (Populus-Betula), oak-hickory (Quercus-Carya) and oak-pine (Quercus-Pinus) forests than other physiographic zones. Most of the combinations showed consistent SDImax between two time periods. Only six combinations showed a significant gain (4–14% increase), which was likely driven by the growth of the same dominant species groups. The findings of this work provided not only additional insights of maximum stand density in the region, but also a methodology for forest ecologists and managers to quantify SDImax for a variety of forest types.

Making the US national forest inventory spatially contiguous and temporally consistent

Signatories to the United Nations Framework Convention on Climate Change (UNFCCC) are required to annually report economy-wide greenhouse gas emissions and removals, including the forest sector. National forest inventory (NFI) is considered the main source of data for reporting forest carbon stocks and changes to UNFCCC. However, NFI samples are often collected asynchronously across regions in intervals of 5–10 years or sub-sampled annually, both introducing uncertainties in estimating annual carbon stock changes by missing a wide range of forest disturbance and recovery processes. Here, we integrate satellite observations with forest inventory data across the conterminous United States to improve the spatial and temporal resolution of NFI for estimating annual carbon stocks and changes. We used more than 120 000 permanent plots from the US forest inventory and analysis (FIA) data, surveyed periodically at sampling rate of 15%–20% per year across the US to develop non-parametric remote sensing-based models of aboveground biomass carbon density (AGC) at 1 ha spatial resolution for the years 2005, 2010, 2015, 2016, and 2017. The model provided a relatively unbiased estimation of AGC compared to ground inventory estimates at plot, county, and state scales. The uncertainty of the biomass maps and their contributions to estimates of forest carbon stock changes at county and state levels were quantified. Our results suggest that adding spatial and temporal dimensions to the forest inventory data, will significantly improve the accuracy and precision of carbon stocks and changes at jurisdictional scales.

Ecosystem Management & the Evolution of Ideas at the US Forest Service

In the early 1990s, ecosystem management was touted as an emerging new paradigm for US national forest planning, but by the end of the decade the phrase had virtually disappeared from public discussion of the subject. The purpose of this article is to understand what legacy, if any, that ecosystem management left on national forest management. While Klyza (1996) has arguably offered the leading viewpoint on how policy ideas influence change in national forest management, this article relies more heavily on insights from the work of Carstensen (2011) and other scholars who view policy idea change as an evolutionary process. Ultimately, it is concluded that ecosystem management was one component of a longer-term evolution in ideas that culminated most recently in the promulgation of the 2012 forest planning rules.

Disturbance shapes the US forest governance frontier: A review and conceptual framework for understanding governance change.

Conflict in US forest management for decades centered around balancing demands from forested ecosystems, with a rise in place-based collaborative governance at the end of the twentieth century. By the early 2000s, it was becoming apparent that not only had the mix of players involved in forest management changed, but so had the playing field, as climate-driven disturbances such as wildfire and insect and disease outbreaks were becoming more extensive and severe. In this conceptual review paper, we argue that disturbance has become the most prominent driver of governance change on US national forests, but we also recognize that the governance responses to disturbance are shaped by variables such as discourses, institutional history and path dependence, and institutional innovation operating at different system levels. We review the governance changes in response to disturbance that constitute a new frontier in US federal forest governance and offer a conceptual framework to examine how these governance responses are shaped by multi-level factors.

Relative density of United States forests has shifted to higher levels over last two decades with important implications for future dynamics

Tree size-density dynamics can inform key trends in forest productivity along with opportunities to increase ecosystem resiliency. Here, we employ a novel approach to estimate the relative density (RD, range 0–1) of any given forest based on its current size-density relationship compared to a hypothetical maximum using the coterminous US national forest inventory between 1999 and 2020. The analysis suggests a static forest land area in the US with less tree abundance but greatly increased timber volume and tree biomass. Coupled with these resource trends, an increase in RD was identified with 90% of US forest land now reaching a biologically-relevant threshold of canopy closure and/or self-thinning induced mortality (RD > 0.3), particularly in areas prone to future drought conditions (e.g., West Coast). Notably, the area of high RD stands (RD > 0.6) has quintupled over the past 20 years while the least stocked stands (RD < 0.3) have decreased 3%. The evidence from the coterminous US forest RD distribution suggest opportunities to increase live tree stocking in understocked stands, while using density management to address tree mortality and resilience to disturbances in increasingly dense forests.

Planning for future fire: Scenario analysis of an accelerated fuel reduction plan for the western United States

Recent fire seasons brought a new fire reality to the western US, and motivated federal agencies to explore scenarios for augmenting current fuel management and forest restoration in areas where fires might threaten critical resources and developed areas. To support this effort, we modeled the scheduling of an accelerated forest and fuel management scenario on 76 western US national forests. Specifically, we modeled a 10-year ramp up of current forest and fuel management that targeted the source of wildfire exposure to developed areas and simulated treatment in areas that accounted for 77% of the predicted exposure. We used a sample of 30 future fire seasons to understand how the plan might be impacted by wildfires and treatment. We found that once fully implemented more than 20% of simulated fires on national forests overlapped fuel treatments, and that roughly 20% of the projects were burned prior to their implementation, suggesting that any plan will undergo significant revision during implementation. Treated areas intersected by wildfire accounted for twice the exposure than non-treated areas that also burned. The study demonstrates the use of scenario planning to design a fuel treatment program that targets wildfire exposure to developed areas, and the methods pave the way for expanded use of scenario planning science to analyze and communicate large scale expansion of current forest and fuel management initiatives.

Does conserving roadless wildland increase wildfire activity in western US national forests?

National forests in the western United States are divided roughly in half between lands without roads managed for wilderness characteristics and lands with an extensive road system managed for multiple uses including resource extraction. We investigated the influence of these land use designations on fire ignitions, fire extent, and fire severity over the last three decades. Although roadless areas experienced fewer fire ignitions and are generally cooler, moister, and higher elevation landscapes less conducive to fire, wildfire extent was far greater in these areas than in roaded areas. An area equivalent to approximately one-third of roadless areas burned in the last three decades, while an area equivalent to less than one-fifth of roaded areas experienced fire. Most of the largest fires that have burned on national forest land in recent years began in roadless areas. Despite greater fire extent in roadless areas, there was no significant difference in fire severity between roadless areas and roaded areas after accounting for biophysical differences between these management regimes. Although fire patterns in roadless areas may pose challenges to land managers, the available evidence suggests that the greater extent of fire in roadless areas may confer resilience to these landscapes in the face of climate change.

Demand for and Economic Value of Nonmotorized Boating Access in Rivers at US National Forests

AbstractNonmotorized boating (NMB) is a popular recreation activity in the US National Forest System. Previous studies on NMB were from an individual river or site, which limited aggregating benefit across the system or generalizing to rivers across the country. Further, whether and how site and river characteristics affect the use of rivers for NMB activities are unknown. This study combined trip data collected from visitor surveys across the system with spatially explicit data on river characteristics in a travel cost model, and in the analysis step, characterized the economic benefit of NMB access and evaluated the effect of site and river characteristics. Net economic benefit of NMB access was estimated to be in the range of $56 to $73 per trip, depending on the modeling assumptions used. When aggregated across visits over the country, the total annual economic value of NMB access in National Forest System ranged from $92 million to $120 million. Results further suggest that site and river characteristics including water velocity, ramp availability, and rapid level were significantly related to NMB demand. Results may be useful in highlighting the use and public value of NMB access in rivers and in understanding the importance of site and river characteristics.

Past and present individual-tree damage assessments of the US national forest inventory.

Identifying the signs and symptoms of pathogens, insects, and other biotic and abiotic agents provides valuable information about the absolute and relative impacts of different types of damage across the forest landscape. In the USA, damage collection protocols have been included in various forms since the initiation of state-level forest surveys in the early twentieth century; however, changes in the protocols over time have made it difficult for the data to be used to its full potential. This article outlines differences in protocols across inventory regions, changes in protocols over time, and limitations and utility of the data so that those interested in using the US national forest inventory database will better understand what data are available and how they have been and can be used.

Impacts of Climate Change on Hydroclimatic Conditions of U.S. National Forests and Grasslands

The conterminous United States includes national forests and grasslands that provide ecological, social, economic, recreational, and aesthetic services. Future climate change can alter long-term hydroclimatic conditions of national forests and grasslands and lead to negative consequences. This study characterizes shifts in hydroclimatology and basin characteristics of US National Forests (NFs) and National Grasslands (NGs) in response to climate change over the 21st century under the DRY, MIDDLE, and WET climate models with the representative concentration pathway (RCP) 8.5 emission scenario. Climatic projections for three climate models ranging from the driest to wettest conditions were obtained from the Multivariate Adaptive Constructed Analogs (MACA) dataset. Then, the variable infiltration capacity (VIC) model was used to model hydrological responses of the selected future climates. Changes in regional hydroclimatic conditions of NFs and NGs were assessed by the magnitude and direction of movements in the Budyko space. The Fu’s equation was applied to estimate changes in basin characteristics. The results indicate that NFs and NGs are likely to experience larger changes in basin characteristics compared to the average of the United States. In general, across the conterminous US, the NFs in mountainous regions are likely to have larger changes in hydroclimatic variables than NFs with lower elevation and NGs. Comparing Forest Service regions, Pacific Northwest, Intermountain, and Northern regions may have a less arid climate with lower freshwater availability. The Southwestern, Northern, Intermountain, and Rocky Mountain regions are likely to experience higher shifts in their basin characteristics. This study can help environmental scientists, and land and water managers improve future land management plans.

An Empirical Evaluation of the Impact of Collaboration on the Pace and Scale of National Forest Management in Idaho

Abstract It has been posited that US national forest administration is undergoing a governance transition characterized by an increase in the involvement and influence of non-state actors. One example of this new form of national forest governance is the use of multi-stakeholder collaborative efforts for planning and implementing projects. This has raised normative and positive questions about the value and effectiveness of such efforts and how they compare with more traditional public involvement and planning processes. This study attempts to address the latter questions by analyzing project-level planning and implementation data while comparing collaborative and traditional projects on a suite of metrics related to pace, scale, complexity, and legal outcomes. We used administrative data from the USDA Forest Service to conduct a quantitative analysis of projects over a 14-year period. We found that collaboratively developed projects were larger and more complex than traditional projects and were associated with greater planning efficiency. This analysis responds to the need to systematically assess the impact of collaborative governance and contributes to existing theories of governance, organizational learning, and policy implementation.

Shifting Perspectives in Assessing Socio-Environmental Vulnerability

Governments and institutions across the globe are conducting vulnerability assessments and developing adaptation plans to confront rapidly changing climatic conditions. Interrelated priorities, including the conservation of biodiversity, ecological restoration, sustainable development, and social justice often underlie these efforts. We collaborated with colleagues in an effort to help guide vulnerability assessment and adaptation (VAA) generally in Southeast Asia and specifically in the watershed of the Sirindhorn International Environmental Park (SIEP) in Phetchaburi Province, Thailand. Reflecting upon our experiences and a review of recent VAA literature, we examine a series of seven questions that help to frame the socio-ecological context for VAAs. We then propose a three-dimensional framework for understanding common orientations of VAAs and how they appear to be shifting and broadening over time, particularly in the USA. For example, key leaders in the SIEP project emphasized social development and community-based approaches over more ecology-centric approaches; this orientation was consistent with other examples from SE Asia. In contrast, many efforts for US national forests have evaluated vulnerability based on projected shifts in vegetation and have promoted adaptation options based upon ecological restoration. Illustrating a third, highly integrated approach, many VAAs prepared by indigenous tribes in the USA have emphasized restoring historical ecological conditions within a broader context of promoting cultural traditions, social justice, and adaptive capacity. We conclude with lessons learned and suggestions for advancing integrated approaches.