United States Forest Research Articles

Bailouts and the Preservation of Competition: The Case of the Federal Timber Contract Payment Modification Act

We estimate the value of competition in United States Forest Service (USFS) timber auctions, in the context of the Reagan administration's bailout of firms that faced substantial losses on existing contracts. We use a model with endogenous entry by asymmetric firms, allowing survivors to respond to the exit of bailed-out firms by entering more auctions and for these marginal entrants to have lower values than firms that would choose to enter in any event, a selective entry effect. Observed asymmetries and selective entry contribute to us finding that the bailout may have increased USFS revenues in subsequent auctions quite substantially. (JEL D44, H81, H82, L73, Q23)

Application of the remote-sensing communication model to a time-sensitive wildfire remote-sensing system

ABSTRACTRemote sensing for hazard response requires a priori identification of sensor, transmission, processing, and distribution methods to permit the extraction of relevant information in timescales sufficient to allow managers to make a given time-sensitive decision. This study applies and demonstrates the utility of the Remote Sensing Communication Model (RSCM) to improve a tactical wildfire remote-sensing system to better meet the time-sensitive information requirements of emergency response managers in San Diego County, USA. A thermal infrared airborne remote-sensing system designed and operated by the United States Forest Service Pacific Southwest Research Station for active wildfire monitoring is documented and updated based on the RSCM. Analysis of the thermal infrared remote-sensing system in the context of the RSCM identified three configuration changes that can improve the effectiveness of the information produced when employed by wildfire incident commanders for suppression prioritization: (1) limit spectral sampling collection to a single waveband; (2) complete image processing steps on-board the aircraft; and (3) provide information on wildfire locations to incident commanders in the form of a static map.

Environmental Reviews and Case Studies: Eastern Hemlock Conservation: A Collaborative Approach to Prioritization through a Diverse Partnership

Eastern hemlock [Tsuga canadensis (L.) Carriere] is a valuable component of Allegheny Plateau forests in northwestern Pennsylvania and western New York. Since the 1950s, hemlock forests throughout the Central Appalachians have been under threat from a nonnative forest insect pest, the hemlock woolly adelgid (Adelges tsugae Annand). In 2012, to address this threat at the most meaningful scale, the United States Forest Service and The Nature Conservancy organized a diverse partnership to develop a strategy for landscape-level conservation of hemlock on the High Allegheny Unglaciated Plateau. The main goal of the partnership was to locate hemlock across the landscape regardless of land ownership and prioritize the hemlock for monitoring and protection from the adelgid. The priority Hemlock Conservation Areas that were identified by this partnership provide a guide for focusing limited financial and personnel resources, with the goal of protecting at least a portion of these areas from the impacts of the adelgid until more long-term management techniques are identified. To protect the important hemlock forests identified in this prioritization, a partnership of private and public land managers are forming a Cooperative Pest Management Area to continue this important collaboration, allocate scarce resources across the area, and allow private partners access to public funding for protection of priority hemlock on their lands. Environmental Practice 18: 94–105 (2016)

Contributing factors for drought in United States forest ecosystems under projected future climates and their uncertainty

Observations of increasing global forest die-off related to drought are leading to more questions about potential increases in drought occurrence, severity, and ecological consequence in the future. Dry soils and warm temperatures interact to affect trees during drought; so understanding shifting risks requires some understanding of changes in both temperature and precipitation. Unfortunately, strong precipitation uncertainties in climate models yield substantial uncertainty in projections of drought occurrence. We argue that disambiguation of drought effects into temperature and precipitation-mediated processes can alleviate some of the implied uncertainty. In particular, the disambiguation can clarify geographic diversity in forest sensitivity to multifarious drivers of drought and mortality, making more specific use of geographically diverse climate projections. Such a framework may provide forest managers with an easier heuristic in discerning geographically diverse adaptation options. Warming temperatures in the future mean three things with respect to drought in forests: (1) droughts, typically already unusually hot periods, will become hotter, (2) the drying capacity of the air, measured as the vapor pressure deficit (VPD) will become greater, and (3) a smaller fraction of precipitation will fall as snow. More hot-temperature extremes will be more stressful in a direct way to living tissue, and greater VPD will increase pressure gradients within trees, exacerbating the risk of hydraulic failure. Reduced storage in snowpacks reduces summer water availability in some places. Warmer temperatures do not directly cause drier soils, however. In a hydrologic sense, warmer temperatures do little to cause “drought” as defined by water balances. Instead, much of the future additional longwave energy flux is expected to cause warming rather than evaporating water. Precipitation variations, in contrast, affect water balances and moisture availability directly; so uncertainties in future precipitation generate uncertainty in drought occurrence and severity projections. Although specific projections in annual and seasonal precipitation are uncertain, changes in inter-storm spacing and precipitation type (snow vs. rain) have greater certainty and may have utility in improving spatial projections of drought as perceived by vegetation, a value not currently captured by simple temperature-driven evaporation projections. This review ties different types of future climate shifts to expected consequences for drought and potential influences on physiology, and then explains sources of uncertainty for consideration in future mortality projections. One intention is to provide guidance on partitioning of uncertainty in projections of forest stresses.

Nonnative forest insects and pathogens in the United States: Impacts and policy options.

We review and synthesize information on invasions of nonnative forest insects and diseases in the United States, including their ecological and economic impacts, pathways of arrival, distribution within the United States, and policy options for reducing future invasions. Nonnative insects have accumulated in United States forests at a rate of ~2.5 per yr over the last 150 yr. Currently the two major pathways of introduction are importation of live plants and wood packing material such as pallets and crates. Introduced insects and diseases occur in forests and cities throughout the United States, and the problem is particularly severe in the Northeast and Upper Midwest. Nonnative forest pests are the only disturbance agent that has effectively eliminated entire tree species or genera from United States forests within decades. The resulting shift in forest structure and species composition alters ecosystem functions such as productivity, nutrient cycling, and wildlife habitat. In urban and suburban areas, loss of trees from streets, yards, and parks affects aesthetics, property values, shading, stormwater runoff, and human health. The economic damage from nonnative pests is not yet fully known, but is likely in the billions of dollars per year, with the majority of this economic burden borne by municipalities and residential property owners. Current policies for preventing introductions are having positive effects but are insufficient to reduce the influx of pests in the face of burgeoning global trade. Options are available to strengthen the defenses against pest arrival and establishment, including measures taken in the exporting country prior to shipment, measures to ensure clean shipments of plants and wood products, inspections at ports of entry, and post‐entry measures such as quarantines, surveillance, and eradication programs. Improved data collection procedures for inspections, greater data accessibility, and better reporting would support better evaluation of policy effectiveness. Lack of additional action places the nation, local municipalities, and property owners at high risk of further damaging and costly invasions. Adopting stronger policies to reduce establishments of new forest insects and diseases would shift the major costs of control to the source and alleviate the economic burden now borne by homeowners and municipalities.

Pattern and Drivers of White-Tailed Deer (Odocoileus virginianus) Herbivory on Tree Saplings across a Plateau Landscape

White-tailed deer (Odocoileus virginianus) populations are impacting long-term regeneration across eastern United States forests. Deer distribution and resulting herbivory patterns are variable across a landscape due to habitat patchiness and topography. It is poorly understood how features associated with topography control deer herbivory. We examined the heterogeneity of deer herbivory as it affects sapling densities across a single forest-type landscape on the Cumberland Plateau. The 1242 hectare site represented a peninsula of tableland that transitioned from developed land to forest and was surrounded on three sides by a bluff, irregularly punctuated by drainages. We examined the spatial variability of deer impacts on sapling density and modeled the relative importance of plateau accessibility features related to topography, proximity to edge, and deer culling as predictors of sapling variation. We used a stratified random design to sample sapling density across the landscape in 2012 and 2015. The intensity of deer herbivory on saplings varied, with the fewest saplings in forests surrounded by residential development. Our model predicted that plateau accessibility measures best determined sapling densities, followed by distance from edge and deer culling measures. Our results suggest that herbivory impacts may not be homogeneous in a contiguous uniform landscape if there are topographic barriers.

A review of the relationships between drought and forest fire in the United States.

The historical and presettlement relationships between drought and wildfire are well documented in North America, with forest fire occurrence and area clearly increasing in response to drought. There is also evidence that drought interacts with other controls (forest productivity, topography, fire weather, management activities) to affect fire intensity, severity, extent, and frequency. Fire regime characteristics arise across many individual fires at a variety of spatial and temporal scales, so both weather and climate - including short- and long-term droughts - are important and influence several, but not all, aspects of fire regimes. We review relationships between drought and fire regimes in United States forests, fire-related drought metrics and expected changes in fire risk, and implications for fire management under climate change. Collectively, this points to a conceptual model of fire on real landscapes: fire regimes, and how they change through time, are products of fuels and how other factors affect their availability (abundance, arrangement, continuity) and flammability (moisture, chemical composition). Climate, management, and land use all affect availability, flammability, and probability of ignition differently in different parts of North America. From a fire ecology perspective, the concept of drought varies with scale, application, scientific or management objective, and ecosystem.

Effects of an ongoing oak savanna restoration on small mammals in Lower Michigan

Oak (Quercus spp.) savannas have declined drastically in the midwestern United States since European settlement. Oak savanna restoration projects are primarily driven by species closely linked to this habitat type, such as the federally endangered Karner blue butterfly (Lycaeides melissa samuelis). However, it is essential that other species are monitored during restoration. Small mammals, due to their importance in ecosystem function, are particularly useful to study. The United States Forest Service is currently conducting an oak savanna restoration in the Manistee National Forest in Lower Michigan using forest thinning and prescribed burning. To understand management impacts on small mammal communities, we live trapped small mammals in each of the mechanically thinned plots (i.e., bulldozer, masticator, and shear cutter) and control plots in five blocks over six years (2008–2013), as well as measured vegetation variables each year. Initially, we used a permutation multivariate analysis of variance (perMANOVA) to determine if there were treatment and year interactions for both small mammal community assemblages and vegetation variables. We then compared changes in small mammal diversity, relative abundance, and vegetation variables among treatments using exploratory randomized block design analysis of variances (ANOVAs). Canopy cover was significantly lower in bulldozer and shear cutter thinned plots than control plots five years following thinning. We observed significant treatment by year interactions in how the small mammal community responded. A large increase in relative abundance of white-footed mice occurred one year post-thinning in all treatments. Within 1–2years of treatment, thirteen-lined ground squirrels and meadow jumping mice, both open-canopy grassland species became established on thinned plots. The retention of brush piles in bulldozer and shear cutter plots provided important refuge habitat for small mammals following thinning. Restoration efforts were beneficial to the small mammal community overall and promoted grassland species to immigrate into the restored area.

Estimating mercury emissions resulting from wildfire in forests of the Western United States

Understanding the emissions of mercury (Hg) from wildfires is important for quantifying the global atmospheric Hg sources. Emissions of Hg from soils resulting from wildfires in the Western United States was estimated for the 2000 to 2013 period, and the potential emission of Hg from forest soils was assessed as a function of forest type and soil-heating. Wildfire released an annual average of 3100±1900kg-Hgy−1 for the years spanning 2000–2013 in the 11 states within the study area. This estimate is nearly 5-fold lower than previous estimates for the study region. Lower emission estimates are attributed to an inclusion of fire severity within burn perimeters. Within reported wildfire perimeters, the average distribution of low, moderate, and high severity burns was 52, 29, and 19% of the total area, respectively. Review of literature data suggests that that low severity burning does not result in soil heating, moderate severity fire results in shallow soil heating, and high severity fire results in relatively deep soil heating (<5cm). Using this approach, emission factors for high severity burns ranged from 58 to 640μg-Hgkg-fuel−1. In contrast, low severity burns have emission factors that are estimated to be only 18–34μg-Hgkg-fuel−1. In this estimate, wildfire is predicted to release 1–30gHgha−1 from Western United States forest soils while above ground fuels are projected to contribute an additional 0.9 to 7.8gHgha−1. Land cover types with low biomass (desert scrub) are projected to release less than 1gHgha−1. Following soil sources, fuel source contributions to total Hg emissions generally followed the order of duff>wood>foliage>litter>branches.

Employing resilience in the United States Forest Service

The concept of resilience has permeated the discourse of many land use and environmental agencies in an attempt to articulate how to develop and implement policies concerned with the social and ecological dimensions of natural disturbances. Several distinct definitions of resilience exist, each with its own concepts, focus and contexts related to land use policy and management. This often makes understanding the inherent objectives of policies and related principles challenging. The United States Forest Service (USFS) is one example where ambiguity and uncertainty surrounding the use of resilience permeates the content of documents in various areas of the agency. The objective of this paper is to investigate how the USFS employs the term resilience as a means to communicate strategies for managing forest lands. We perform a content analysis of 121 USFS documents including budgetary justification reports, research findings (i.e., journal articles, book chapters and technical reports), public releases, and newsletters to analyze both the rise and specific use of the term resilience in the USFS. Our analysis, which is guided by definitions of resilience in the social-ecological systems literature, reveals that the ambiguity surrounding the use of resilience in the academic literature is reflected in the content of USFS documents. However, we also find that often criticized versions of resilience (namely engineering resilience) are minimally employed by the USFS, and instead the agency focuses on the notion of ecological resilience in which natural disturbances are seen as an important component of the landscape. In some cases, the USFS employs notions of social-ecological resilience, however, the extent to which specific components of social-ecological resilience are integrated into management strategies appears minimal. The findings from this study suggest that clarity regarding the type and function of resilience needs to improve in USFS documents, and that the agency should evaluate the existing question in the SES literature of resilience of what to what?

Governing adaptation across scales: Hotspots and hesitancy in Pacific Northwest forests

The observed and anticipated impacts of climate change interacting with the responses of actors and institutions to these changes are together poised to transform and reconfigure resource management systems across scales. Within many if not most resource management agencies, the number of programs and initiatives designed to adapt to the expected impacts of climate change has risen sharply over the past decade. This article examines the implementation of such climate adaptation initiatives in the context of the United States Forest Service (USFS). Based on semi-structured interviews (N=25), this paper provides an empirical account of how USFS aquatic resources managers and specialists working at regional and sub-regional levels within the Pacific Northwest region (PNW) are responding to adaptation planning directives established at the federal level, as well as how managers are advancing their own unit-level initiatives. Results illustrate a spectrum of engagement with adaptation across the region. In addition to the expected influence of limited human and financial capacity and institutional constraints, key factors perceived by managers as shaping engagement across the region include the attitudes of key actors, and legacies of (mis-) trust (with respect to the stability of the climate mandate). In contrast, managers did not perceive technical information as a major barrier to adaptation. These observations highlight the asymmetry between the widespread emphasis on the role of technical information in shaping adaptation relative to the often overlooked, but influential role of nonmaterial factors (like attitudes and trust). Findings are discussed in the context of deepening understanding about the interrelated roles of material and nonmaterial barriers in shaping currently unfolding adaptation efforts.

Landsat Image Analysis of Tree Mortality in the Southern Sierra Nevada Region of California during the 2013-2015 Drought

The United States Forest Service (USFS) observed marked increases in tree mortality in the southern Sierra Nevada foothills and mountains of California using aerial monitoring surveys in April 2015. Aircraft flew over 4 million acres of forested land and found that about 20 percent of forest stands had detectable mortality, totaling 10.45 million dead trees. In this study, Landsat satellite imagery was analyzed at over 90% of these high tree mortality sites in the southern Sierra to understand how the three consecutive years (2013-2015) of extreme drought conditions compared to changes in forest stand growth rates dating to the mid-1980s across this region. Results showed that changes in Landsat droughtsensitive indices from the years 2011 to 2015 closely matched patterns of tree mortality across USFS April 2015 aerial survey locations in the southern Sierra Nevada. The historically low snow year of 2015 could have essentially reset the average forest canopy density for many forests in the region to late 1980s levels, due to drought-related mortality, combined with numerous large stand-replacing wildfires. The corresponding patterns and trends in Landast droughtsensitive indices with observed tree mortality rates can better inform region-wide assessments of forest growth trends and enable long-term drought impact monitoring.

Historical reconstructions of California wildfires vary by data source

Historical data are essential for understanding how fire activity responds to different drivers. It is important that the source of data is commensurate with the spatial and temporal scale of the question addressed, but fire history databases are derived from different sources with different restrictions. In California, a frequently used fire history dataset is the State of California Fire and Resource Assessment Program (FRAP) fire history database, which circumscribes fire perimeters at a relatively fine scale. It includes large fires on both state and federal lands but only covers fires that were mapped or had other spatially explicit data. A different database is the state and federal governments’ annual reports of all fires. They are more complete than the FRAP database but are only spatially explicit to the level of county (California Department of Forestry and Fire Protection – Cal Fire) or forest (United States Forest Service – USFS). We found substantial differences between the FRAP database and the annual summaries, with the largest and most consistent discrepancy being in fire frequency. The FRAP database missed the majority of fires and is thus a poor indicator of fire frequency or indicators of ignition sources. The FRAP database is also deficient in area burned, especially before 1950. Even in contemporary records, the huge number of smaller fires not included in the FRAP database account for substantial cumulative differences in area burned. Wildfires in California account for nearly half of the western United States fire suppression budget. Therefore, the conclusions about data discrepancies and the implications for fire research are of broad importance.

Warm summer nights and the growth decline of shore pine in Southeast Alaska

Shore pine, which is a subspecies of lodgepole pine, was a widespread and dominant tree species in Southeast Alaska during the early Holocene. At present, the distribution of shore pine in Alaska is restricted to coastal bogs and fens, likely by competition with Sitka spruce and Western hemlock. Monitoring of permanent plots as part of the United States Forest Service Forest Inventory and Analysis program identified a recent loss of shore pine biomass in Southeast Alaska. The apparent loss of shore pine is concerning, because its presence adds a vertical dimension to coastal wetlands, which are the richest plant communities of the coastal temperate rainforest in Alaska. In this study, we examined the shore pine tree-ring record from a newly established plot network throughout Southeast Alaska and explored climate-growth relationships. We found a steep decline in shore pine growth from the early 1960s to the present. Random Forest regression revealed a strong correlation between the decline in shore pine growth and the rise in growing season diurnal minimum air temperature. Warm summer nights, cool daytime temperatures and a reduced diurnal temperature range are associated with greater cloud cover in Southeast Alaska. This suite of conditions could lead to unfavorable tree carbon budgets (reduced daytime photosynthesis and greater nighttime respiration) and/or favor infection by foliar pathogens, such as Dothistroma needle blight, which has recently caused widespread tree mortality on lodgepole pine plantations in British Columbia. Further field study that includes experimental manipulation (e.g., fungicide application) will be necessary to identify the proximal cause(s) of the growth decline. In the meantime, we anticipate continuation of the shore pine growth decline in Southeast Alaska.

Quantifying microbial ecophysiological effects on the carbon fluxes of forest ecosystems over the conterminous United States

There is a pressing need to develop earth system models (ESMs), in which ecosystem processes are adequately represented, to quantify carbon-climate feedbacks. In particular, explicit representation of the effects of microbial activities on soil organic carbon decomposition has been slow in ESM development. Here we revised an existing Q10-based heterotrophic respiration (RH) algorithm of a large-scale biogeochemical model, the Terrestrial Ecosystem Model (TEM), by incorporating the algorithms of Dual Arrhenius and Michaelis-Menten kinetics and microbial-enzyme interactions. The microbial physiology enabled model (MIC-TEM) was then applied to quantify historical and future carbon dynamics of forest ecosystems in the conterminous United States. Simulations indicate that warming has a weaker positive effect on RH than that traditional Q10 model has. Our results demonstrate that MIC-TEM is superior to traditional TEM in reproducing historical carbon dynamics. More importantly, the future trend of soil carbon accumulation simulated with MIC-TEM is more reasonable than TEM did and is generally consistent with soil warming experimental studies. The revised model estimates that regional GPP is 2.48 Pg C year−1 (2.02 to 3.03 Pg C year−1) and NEP is 0.10 Pg C year−1 (−0.20 to 0.32 Pg C year−1) during 2000–2005. Both models predict that the conterminous United States forest ecosystems are carbon sinks under two future climate scenarios during the 21st century. This study suggests that terrestrial ecosystem models should explicitly consider the microbial ecophysiological effects on soil carbon decomposition to adequately quantify forest ecosystem carbon fluxes at regional scales.

Space use by white‐headed woodpeckers and selection for recent forest disturbances

ABSTRACTWhite‐headed woodpeckers (Picoides albolarvatus) are important cavity excavators that recently have become the focus of much research because of concerns over population declines. Past studies have focused on nest site selection and survival but information is needed on factors influencing their space use when away from the nest. We examined space use by white‐headed woodpeckers during the nesting (May–Jul) and post‐nesting (Jul–Oct) periods and compared the role of environmental factors (e.g., landcover) and socio‐demographic factors (e.g., age, breeding success) in home range size and selection of location. Average size of 99% kernel home ranges was 125 ha (SD ± 59 ha; n = 19) in the nesting period and 137 ha (SD ± 70 ha; n = 30) in the post‐nesting period. Minimum convex polygons were generally comparable to or smaller than ranges reported from previous radio‐telemetry studies with this species. Although bird weight and age best explained variation in home range size compared to other factors, neither parameter estimate was significant in our models. Thus, even though weight and age were the most‐supported factors in our analysis, home range size was largely influenced by factors that we did not measure. We found that most woodpeckers selected home ranges within forest patches that had undergone a recent disturbance; these areas included forests that had recently been burned with prescribed fire by the United States Forest Service (82%) or subject to disease (16%). Most burned patches in our study were small (approx. 4.8 ha) and occurred within otherwise live forest but had nearly complete mortality of adult trees. We suggest that recent forest disturbances, especially mixed‐severity prescribed burns, may have been selected by white‐headed woodpeckers because they created snags for nesting and future studies should explore this hypothesis. Because home range size was variable and not linked with productivity, it should not be used as an indication of habitat quality without more detailed studies on causal factors that affect space use in this species. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Scale dependence of disease impacts on quaking aspen (Populus tremuloides) mortality in the southwestern United States.

Depending on how disease impacts tree exposure to risk, both the prevalence of disease and disease effects on survival may contribute to patterns of mortality risk across a species' range. Disease may accelerate tree species' declines in response to global change factors, such as drought, biotic interactions, such as competition, or functional traits, such as allometry. To assess the role of disease in mediating mortality risk in quaking aspen (Populus tremuloides), we developed hierarchical Bayesian models for both disease prevalence in live aspen stems and the resulting survival rates of healthy and diseased aspen near the species' southern range limit using 5088 individual trees on 281 United States Forest Service Forest Inventory and Analysis plots in the southwestern United States. We found that disease prevalence depended primarily on tree size, tree allometry, and spatial variation in precipitation, while mortality depended on tree size, allometry, competition, spatial variation in summer temperature, and both temporal and spatial variation in summer precipitation. Disease prevalence was highest in large trees with low slenderness found on dry sites. For healthy trees, mortality decreased with diameter, slenderness, and temporal variation in summer precipitation, but increased with competition and spatial variation in summer temperature. Mortality of diseased trees decreased with diameter and aspen relative basal area and increased with mean summer temperature and precipitation. Disease infection increased aspen mortality, especially in trees of intermediate size and trees on plots at climatic extremes (i.e., cool, wet and warm, dry climates). By examining variation in disease prevalence, mortality of healthy trees, and mortality of diseased trees, we showed that the role of disease in aspen tree mortality depended on the scale of inference. For variation among individuals in diameter, disease tended to expose intermediate-size trees experiencing moderate risk to greater risk. For spatial variation in summer temperature, disease exposed lower risk populations to greater mortality probabilities, but the magnitude of this exposure depended on summer precipitation. Furthermore, the importance of diameter and slenderness in mediating responses to climate supports the increasing emphasis on trait variation in studies of ecological responses to global change.

Developing Woody Crops for the Enhancement of Ecosystem Services under Changing Climates in the North Central United States

Short rotation woody crops belonging to the genera Populus L., Salix L., Pinus L., and Eucalyptus LHer. have provided broad economic and ecological benefits throughout the world, including afforestation and reforestation along urban to rural gradients. Within the genus Populus, cottonwoods, poplars, aspens, and their hybrids (hereafter referred to as poplars) have been shown to exhibit favorable genotype × environment interactions, especially in the face of changing climates. Similar growth responses have been reported for Pinus, especially with white pine (Pinus strobus L.) in the North Central United States. This has led to current research priorities focused on ecosystem services for both genera. The Millennium Ecosystem Assessment (2005) defines cultural, supporting, provisioning, and regulating ecosystem services. The overarching objective of this paper was to synthesize information about the potential of poplars to provide multiple ecosystem services when grown at sites with varying soil and climate conditions across landscape gradients from urban to rural areas. Specific objectives included: 1) providing background of the United States Forest Service and its Research and Development branch, 2) integrating knowledge of current poplar breeding and development with biomass provisioning and carbon regulating ecosystem services as they relate to changing climates in the North Central United States, and 3) providing a case study illustrating this integration through comparisons of poplar with white pine. Our results were evaluated in the context of climate change mitigation, with specific focus on selection of favorable genotypes for sequestering atmospheric carbon and reducing fossil fuel carbon emissions.

Large carbon release legacy from bark beetle outbreaks across Western United States.

Warmer conditions over the past two decades have contributed to rapid expansion of bark beetle outbreaks killing millions of trees over a large fraction of western United States (US) forests. These outbreaks reduce plant productivity by killing trees and transfer carbon from live to dead pools where carbon is slowly emitted to the atmosphere via heterotrophic respiration which subsequently feeds back to climate change. Recent studies have begun to examine the local impacts of bark beetle outbreaks in individual stands, but the full regional carbon consequences remain undocumented for the western US. In this study, we quantify the regional carbon impacts of the bark beetle outbreaks taking place in western US forests. The work relies on a combination of postdisturbance forest regrowth trajectories derived from forest inventory data and a process-based carbon cycle model tracking decomposition, as well as aerial detection survey (ADS) data documenting the regional extent and severity of recent outbreaks. We find that biomass killed by bark beetle attacks across beetle-affected areas in western US forests from 2000 to 2009 ranges from 5 to 15TgCyr(-1) and caused a reduction of net ecosystem productivity (NEP) of about 6.1-9.3TgCy(-1) by 2009. Uncertainties result largely from a lack of detailed surveys of the extent and severity of outbreaks, calling out a need for improved characterization across western US forests. The carbon flux legacy of 2000-2009 outbreaks will continue decades into the future (e.g., 2040-2060) as committed emissions from heterotrophic respiration of beetle-killed biomass are balanced by forest regrowth and accumulation.

Watersheds as Natural Infrastructure: New Urban Water Report Analyzes Benefits

More than a decade ago, residents of New Mexico witnessed the devastation caused by the Cerro Grande fire. Perilous fuel loads from decades of fire suppression caused burning to last for two weeks, leaving in its wake a wasteland of destroyed homes, dead trees, and ash. One year after the fire, reservoir sediment accumulation was 140 times higher than the previous 57 years combined. Levels remained significantly elevated for five years, and costs to clean up damage to the water supply ran $17 million. Water managers in the city of Santa Fe, N.M., took heed and invested, alongside the United States Forest Service, in a forest fuel‐reduction strategy to protect its own watershed. This program helped the city avoid an estimated $22 million in potential damage.