USDA Forest Service Research Articles

Forest Wetland Area and the Forest Sector Economy in the U.S. South

This article reviews current data on forest wetlands and their economic contributions in the South, ranging from Texas to Virginia. Based on USDA Forest Service Forest Inventory and Analysis (FIA) data, the wetland category comprised 17.7% of timber land area on all private and public lands in the South. This included 4.25 million ha of hydric sites; 0.77 million ha mesic wet; 9.55 million ha mesic, with only seasonal access; for a total of 14.57 million ha. The Natural Resource Inventory (NRI) for 2012 on private lands estimated that there were 14.71 million ha forested wetlands, which comprised 17.7% of all forested private forest area. The 2015 National Land Cover Data for the South estimated that there were 17.8 million ha of woody wetlands, which comprised 8% to 12% of the southern land area, and there were also 4.45 million ha of emergent herbaceous sites. About 10% of the southern timber forest sector would be based on harvests from wetland forests economy ($455 million per year), while the 17.7% of wetland land area would provide a proportional share of the annual nontimber forest products ($44 million) and payments for ecosystem services ($134 million). Wetlands also provide important nontimber forest products, and ecosystem services, which are beginning to develop active private and public markets.

First Report of ‘Candidatus Phytoplasma trifolii’-Related Strain of 16SrVI-A Phytoplasma Subgroup, Associated with Elm Yellows Disease in American Elm (Ulmus americana L.) in Ohio, U.S.A

During the investigation of the sudden and early onset of yellowing, followed by mortality of American elm (Ulmus americana L.) trees at the USDA Forest Service Northern Research Station in Delaware, Ohio, a phytoplasma of the clover proliferation group (16SrVI) was detected as the putative causal agent of the disease outbreak. Onset of symptoms was rapid and widespread, occurring in late July 2016 and affecting ∼60 trees across two elm research plantations. Symptoms included a general yellowing of individual tree canopies, epinasty of foliage throughout the canopy, phloem discoloration, and on a subset of trees, a strong odor of methyl salicylate (observed in phloem tissue extracted from the lower stem). Similar symptoms in elms have been attributed to the classic elm yellows ‘Candidatus Phytoplasma ulmi’ (16SrV-A) (Lee et al. 2004) and the Illinois elm yellows phytoplasma (16SrVI-C) (Jacobs et al. 2003). In July 2016, samples were collected from 12 symptomatic and 8 asymptomatic American elm trees. DNA from the leaf midrib and branch phloem was isolated and analyzed for phytoplasma via seminested polymerase chain reactions (PCR). PCRs were first primed by phytoplasma universal primer pair P5/P7 (Jomantiene et al. 1998), followed by P7 and the reverse complement of the universal phytoplasma primer R16R2 for amplification of the phytoplasma 16S-23 ribosomal (r) DNA (16S-23 rRNA gene) sequences as per Gundersen and Lee (1996). The predicted band size of the second PCR product is 487 base pair (bp). The product bands were isolated, purified, and sequenced using primer P7. Sequencing results of the PCR products indicated that nine of the symptomatic and one of the asymptomatic American elm trees tested were infected by a phytoplasma. A BLAST search of the DNA sequences indicated high similarities to members of the ‘Ca. P. trifolii’ group 16SrVI-A. The sequences of all 10 phytoplasma-infected trees were identical to each other. To further confirm that a strain of ‘Ca. P. trifolii’ was infecting the elms, a PCR product was cloned and sequenced. The 1,557 bp band was the product of primers P1a/P7, followed by PCR primers designed from the sequence of ‘Ca. P. trifolii’. This band was cloned into the pMiniT 2.0 vector. Plasmid sequencing used standard sequencing primers (SP6 and T7 promoters), the primers included with the vector, and finally, custom designed phytoplasma primers that eliminate other bacterial DNA from getting amplified. The entire plasmid clone was sequenced in both directions with four to six times of coverage per base. Determination of the phytoplasma classification group was based on the nucleotide sequence within the phytoplasma universal primers F2n/R2 PCR fragment within the 16Sr gene. Using iPhyClassifier, the online tool for phytoplasma classification and taxonomic assignment (https://plantpathology.ba.ars.usda.gov/cgi-bin/resource/iphyclassifier.cgi), the sequence similarity between the Delaware elm phytoplasma and ‘Ca. P. trifolii’ (GenBank accession no. AB279597.1) is 99.9% in the 16Sr region, which places the Delaware elm phytoplasma in the 16SrVI-A group. The sequence of the plasmid was deposited in GenBank under accession number MF385584. Elm decline and yellows diseases in North America have been associated with the Illinois elm yellows phytoplasma (16SrVI-C, GenBank accession no. AF268893.1) (Jacobs et al. 2003), ‘Ca. Phytoplasma ulmi’ (16SrV-A) (Lee et al. 2004), and phytoplasma in the aster yellows group (16SrI-C) (Lee et al. 1995).

The complete genome sequence of a third distinct baculovirus isolated from the true armyworm, Mythimna unipuncta, contains two copies of the lef-7 gene

A baculovirus isolate from a USDA Forest Service collection was characterized by electron microscopy and analysis of its genome sequence. The isolate, formerly referred to as Pseudoletia (Mythimna) sp. nucleopolyhedrovirus #7 (MyspNPV#7), was determined by barcoding PCR to derive from the host species Mythimna unipuncta (true armyworm) and was renamed Mythimna unipuncta nucleopolyhedrovirus #7 (MyunNPV#7). The occlusion bodies (OBs) and virions exhibited a size and morphology typical for OBs produced by the species of genus Alphabaculovirus, with occlusion-derived virions consisting of 2-5 nucleocapsids within a single envelope. The MyunNPV#7 genome was determined to be 148,482bp with a 48.58% G+C nucleotide distribution. A total of 159 ORFs of 150bp or larger were annotated in the genome sequence, including the 38 core genes of family Baculoviridae. The genome contained six homologous repeat regions (hrs) consisting of multiple copies of a 34-bp imperfect palindrome. Phylogenetic inference from concatenated baculovirus core gene amino acid sequence alignments placed MyunNPV#7 with group II alphabaculoviruses isolated from other armyworm and cutworm host species of lepidopteran family Noctuidae. MyunNPV#7 could be distinguished from other viruses in this group on the basis of differences in gene content and order. Pairwise nucleotide distances suggested that MyunNPV#7 represents a distinct species in Alphabaculovirus. The MyunNPV#7 genome was found to contain two copies of the late expression factor-7 (lef-7) gene, a feature not reported for any other baculovirus genome to date. Both copies of lef-7 encoded an F-box domain, which is required for the function of LEF-7 in baculovirus DNA replication.

Hierarchical Bayesian models for small area estimation of county-level private forest landowner population

The National Woodland Owner Survey (NWOS), administered by the USDA Forest Service, provides estimates of private forest ownership characteristics and owners’ attitudes and behaviors at a national, regional, and state levels. Due to sample sizes prescribed for inference at the state level, there are insufficient data to support county-level estimates. However, county-level estimates of NWOS variables are desired because ownership programs and education initiatives often occur at the county level and such information could help tailor these efforts to better match county-specific needs and demographics. Here, we present and assess methods to estimate the number of private forest ownerships at the county level for two states, Montana and New Jersey. To assess model performance, true population parameters were derived from cadastral and remote sensing data. Two small area estimation (SAE) models, the Fay-Herriot (FH) and the FH with conditional autoregressive random effects (FHCAR), improved estimated county-level population mean squared error (MSE) over that achieved by direct estimates. The proposed SAE models use covariates to improve accuracy and precision of county-level estimates. Results show total forest area, and 2010 decennial census population density covariates explained a significant portion of variability in county-level population size. These and other results suggest that the proposed SAE methods yield a statistically robust approach to deliver reliable estimates of private ownership population size and could be extended to additional important NWOS variables at the county level.

A Land Use and Resource Allocation (LURA) modeling system for projecting localized forest CO2 effects of alternative macroeconomic futures

The United States has recently set ambitious national goals for greenhouse gas (GHG) reductions over the coming decades. A portion of these reductions are based on expected sequestration and storage contributions from land use, land use change, and forestry (LULUCF). Significant uncertainty exists in future forest markets and thus the potential LULUCF contribution to US GHG reduction goals. This study seeks to inform the discussion by modeling US forest GHG accounts per different simulated demand scenarios across a grid of over 130,000 USDA Forest Service Forest Inventory and Analysis (FIA) forestland plots over the conterminous United States. This spatially disaggregated future supply is based on empirical yield functions for log volume, biomass and carbon. Demand data is based on a spatial database of over 2300 forest product manufacturing facilities representing 11 intermediate and 13 final solid and pulpwood products. Transportation costs are derived from fuel prices and the locations of FIA plot from which a log is harvested and mill or port destination. Trade between mills in intermediate products such as sawmill residues or planer shavings is also captured within the model formulation. The resulting partial spatial equilibrium model of the US forest sector is solved annually for the period 2015–2035 with demand shifted by energy prices and macroeconomic indicators from the US EIA's Annual Energy Outlook for a Reference, Low Economic Growth, and High Economic Growth case. For each macroeconomic scenario simulated, figures showing historic and scenario-specific live tree carnon emissions and sequestration are generated. Maps of the spatial allocation of both forest harvesting and related carbon fluxes are presented at the National level and detail is given for both regions and ownerships.

Terrestrial Condition Assessment for National Forests of the USDA Forest Service in the Continental US

The terrestrial condition assessment (TCA) evaluates effects of uncharacteristic stressors and disturbance agents on land-type associations (LTAs) to identify restoration opportunities on national forest system (NFS) lands in the United States. A team of agency scientists and managers, representing a broad array of natural resource disciplines, developed a logic structure for the TCA to identify appropriate data sources to support analyses. Primary national data sources included observed insect- and pathogen-induced mortality, key critical loads for soil and the atmosphere, long term seasonal departures in temperature and precipitation, road densities, uncharacteristic wildfires, historical fire regime departure, wildfire potential, insect and pathogen risk, and vegetation departure from natural range of variability. The TCA was implemented with the ecosystem management decision support (EMDS) system, a spatial decision support system for landscape analysis and planning. EMDS uses logic models to interpret data, synthesizes information over successive layers of logic topics, and draws inferences about the ecological integrity of LTAs as an initial step to identifying high priority LTAs for landscape restoration on NFS lands. Results from the analysis showed that about 74 percent of NFS lands had moderate or better overall ecological integrity. Major impacts to ecological integrity included risk of mortality due to insects and disease, extent of current mortality, extent of areas with high and very high wildfire hazard potential, uncharacteristically severe wildfire, and elevated temperatures. In the discussion, we consider implications for agency performance reporting on restoration activities, and subsequent possible steps, including strategic and tactical planning for restoration. The objective of the paper is to describe the TCA framework with results from a national scale application on NFS lands.

Large-area hybrid estimation of aboveground biomass in interior Alaska using airborne laser scanning data

Use of data from airborne laser scanning (ALS) is a well-established practice for enhancing the accuracy of forest inventories in combination with ground-based observations. For regular monitoring of large areas, wall-to-wall ALS data is economically prohibitive. However, when data are acquired in a strip-sampling mode, ALS can support the estimation of forest resources on large areas such as counties, states, and nations. This study investigated the combined use of ALS data acquired along parallel strips and co-located field observations of live and standing dead trees to estimate aboveground biomass (AGB) at regional and sub-regional levels. The study area comprised the Tanana Inventory Unit (TIU) (138,566km2), located in interior Alaska, and four sub-regions (106–7282km2) within the TIU. The field data consisted of 1676 ground observations from six independent field campaigns. Ninety-four plots came from the Forest Inventory and Analysis (FIA) program of the USDA Forest Service. The FIA plots, each consisting of four 1/60ha subplots, were acquired using a probabilistic sampling design. The remaining ground observations were collected during field inventories across TIU, and consisted of 335 independent field plots and 257 clusters containing up to four plots each. The estimation procedure followed a two-phase sampling design grounded within a hybrid inferential framework, which combines design-based estimation for the first phase and model-based inference in the second phase. Post-stratified estimation by land-cover class indicated that the hybrid estimation obtained 11–55% better precision compared to direct (design-based) estimation based solely on field observations. When the field sample sizes were reduced to 25%, the standard errors for the hybrid estimation increased by 3 to 5pp. Direct and hybrid estimates were compared for two sub-regions, and the hybrid estimated AGBs were 6.4% and 13.3% larger than the direct estimates. On both these study sub-regions, the 95% confidence interval of the hybrid estimated mean AGB included the direct estimate of the mean and vice versa.

Ecosystem Service Supply and Capacity on U.S. Family Forestlands

Individuals and families collectively own more than 118 million ha of forestland in the USA. Using data from the USDA Forest Service’s National Woodland Owners Survey (NWOS), we characterize ecosystem services being produced on family forests as well as the beneficiaries who enjoy them. Approximately half of family forest owners provide one or more provisioning services. With the exception of logs, the provisioning services provided by the majority of owners are enjoyed directly by owners or their close associates (i.e., family, friends, and neighbors). Similarly, while more than half of family forest owners have provided recreational opportunities, a cultural service, to their close associates, fewer than 6% of owners have sold or provided recreational services to the general public. Regulating and supporting services are linked to the maintenance of long-term forest cover. Greater than 80% of family forest owners desire to maintain the forested condition of their land, whereas a much smaller percentage of these owners have entered into conservation easements or have collected money for conservation purposes. In addition, many owners have engaged in activities expected to increase the future capacity of their land to provide multiple ecosystem services, both excludable and non-excludable.

Novel insights on population and range edge dynamics using an unparalleled spatiotemporal record of species invasion.

Quantifying the complex spatial dynamics taking place at range edges is critical for understanding future distributions of species, yet very few systems have sufficient data or the spatial resolution to empirically test these dynamics. This paper reviews how data from a large-scale pest management programme have provided important contributions to the fields of population dynamics and invasion biology. The invasion of gypsy moth (Lymantria dispar) is well-documented from its introduction near Boston, Massachusetts USA in 1869 to its current extent of over 900,000km2 in Eastern North America. Over the past two decades, the USDA Forest Service Slow the Spread (STS) programme for managing the future spread of gypsy moth has produced unrivalled spatiotemporal data across the invasion front. The STS programme annually deploys a grid of 60,000-100,000 pheromone-baited traps, currently extending from Minnesota to North Carolina. The data from this programme have provided the foundation for investigations of complex population dynamics and the ability to examine ecological hypotheses previously untestable outside of theoretical venues, particularly regarding invasive spread and Allee effects. This system provides empirical data on the importance of long-distance dispersal and time-lags on population establishment and spatial spread. Studies showing high rates of spatiotemporal variation of the range edge, from rapid spread to border stasis and even retraction, highlight future opportunities to test mechanisms that influence both invasive and native species ranges. The STS trap data have also created a unique opportunity to study low-density population dynamics and quantify Allee effects with empirical data. Notable contributions include evidence for spatiotemporal variation in Allee effects, demonstrating empirical links between Allee effects and spatial spread, and testing mechanisms of population persistence and growth rates at range edges. There remain several outstanding questions in spatial ecology and population biology that can be tested within this system, such as the scaling of local ecological processes to large-scale dynamics across landscapes. The gypsy moth is an ideal model of how important ecological questions can be answered by thinking more broadly about monitoring data.

Klamath Tribes: Managing Their Homeland Forests in Partnership with the USDA Forest Service

Klamath Tribes: Managing Their Homeland Forests in Partnership with the USDA Forest Service

Working to Address Complex Forest Issues: A Collaborative Case Study between the Mescalero Apache Nation and USDA Forest Service

Working to Address Complex Forest Issues: A Collaborative Case Study between the Mescalero Apache Nation and USDA Forest Service

Translating national level forest service goals to local level land management: carbon sequestration

The USDA Forest Service has many national level policies related to multiple use management. However, translating national policy to stand level forest management can be difficult. As an example of how a national policy can be put into action, we examined three case studies in which a desired future condition is evaluated at the national, region, and local scale. We chose to use carbon sequestration as the desired future condition because climate change has become a major area of concern during the last decade. Several studies have determined that the 193 million acres of US national forest land currently sequester 11 to 15% of the total carbon emitted as a nation. This paper provides a framework by which national scale strategies for maintaining or enhancing forest carbon sequestration is translated through regional considerations and local constraints in adaptive management practices. Although this framework used the carbon sequestration as a case study, this framework could be used with other national level priorities such as the National Environmental Protection Act (NEPA) or the Endangered Species Act (ESA).

Comparison of USDA Forest Service and Stakeholder Motivations and Experiences in Collaborative Federal Forest Governance in the Western United States.

In the United States, over 191 million acres of land is managed by the United States Department of Agriculture Forest Service, a federal government agency. In several western U.S. states, organized collaborative groups have become a de facto governance approach to providing sustained input on management decisions on much public land. This is most extensive in Oregon, where at least 25 "forest collaboratives" currently exist. This affords excellent opportunities for studies of many common themes in collaborative governance, including trust, shared values, and perceptions of success. We undertook a statewide survey of participants in Oregon forest collaboratives to examine differences in motivations, perceptions of success, and satisfaction among Forest Service participants ("agency participants"), who made up 31% of the sample, and other respondents ("non-agency") who represent nonfederal agencies, interest groups, citizens, and non-governmental groups. We found that agency participants differed from non-agency participants. They typically had higher annual incomes, and were primarily motivated to participate to build trust. However, a majority of all respondents were similar in not indicating any other social or economic motivations as their primary reason for collaborating. A majority also reported satisfaction with their collaborative-despite not ranking collaborative performance on a number of specific potential outcomes highly. Together, this suggests that collaboration in Oregon is currently perceived as successful despite not achieving many specific outcomes. Yet there were significant differences in socioeconomic status and motivation that could affect the ability of agency and nonagency participants to develop and achieve mutually-desired goals.

Wildland Fire Impacts on Mercury in Fish

Wildland Fire Impacts on Mercury in Fish

Alternative interpretation and scale-based context for “No evidence of recent (1995–2013) decrease of yellow-cedar in Alaska” (Barrett and Pattison 2017)

In their analysis of resampled and remeasured plot data from the USDA Forest Service Forest Inventory and Analysis (FIA) program, Barrett and Pattison (2017, Can. J. For. Res. 47(1): 97–105, doi: 10.1139/cjfr-2016-0335 ) suggest that there is neither evidence of a recent regional decrease in yellow-cedar (Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little) live tree basal area nor a decrease in the species’ extent in southeastern Alaska. Here, we identify substantial, broad-scale agreement between their estimated extent of concentrated yellow-cedar mortality and that resulting from a complementary, existing body of research into yellow-cedar decline spanning 35 years. However, we also discuss concerns that the FIA remeasurement data used did not match the spatial distribution of the decline (e.g., excluding areas of known active decline in wilderness areas) and that the temporal coverage of FIA data (1990s to 2000s) was inappropriately compared with a cumulative decline map that spans several decades, meshing recent mortality with mortality that occurred up to a century ago. We provide an alternative explanation of Barrett and Pattison’s results in the context of ongoing yellow-cedar distribution and decline research in southeastern Alaska and support our interpretation by focusing on the temporal and spatial aspects of decline.

Monitoring Nontimber Forest Products Using Forest Inventory Data: An Example with Slippery Elm Bark

The USDA Forest Service Forest Inventory and Analysi (FIA) program collects data on a wealth of variables related to trees in forests. Some of these trees produce nontimber forest products (NTFPs) (e.g., fruit, bark and sap) that are harvested for culinary, decorative, building, and medicinal purposes. At least 11 tree species inventoried by FIA are valued for their bark. For example, slippery elm (Ulmus rubra Muhl.) is included in FIA forest inventories, and the bark is used for its medicinal value. Despite widespread use of NTFPs, little quantitative information about abundance, distribution, and harvest is available to support sustainable management. Methods for using the FIA database to monitor and explain the situation regarding selected NTFPs are presented. The focus is on using FIA data to assess for (1) geographic distribution, (2) abundance, (3) applicable metircs (e.g., square feet of bark, and (4) change over time.

The International Institute of Tropical Forestry: Antecedents and present influences on forest entomology in Puerto Rico

An overview of the evolution of the International Institute of Tropical Forestry and activities that have influenced present day forest entomology research and USDA-Forest Service cooperative forest health programs in Puerto Rico.

Biomass Estimates of Small Diameter Planted and Natural-Origin Loblolly Pines Show Major Departures from the National Biomass Estimator Equations

Agriculture and Food Research Initiative Competitive Grant from the USDA National Institute of Food and Agriculture [2009-35103-05356]; Southern Research Station of the USDA Forest Service; Arkansas Forest Resources Center

Dual-Filter Estimation for Rotating-Panel Sample Designs

Dual-filter estimators are described and tested for use in the annual estimation for national forest inventories. The dual-filter approach involves the use of a moving widow estimator in the first pass, which is used as input to Theil’s mixed estimator in the second pass. The moving window and dual-filter estimators are tested along with two other estimators in a sampling simulation of 152 simulated populations, which were developed from data collected in 38 states and Puerto Rico by the Forest Inventory and Analysis Program of the USDA Forest Service. The dual-filter estimators are shown to almost always provide some reduction in mean squared error (MSE) relative to the first pass moving window estimators.

Ecosystem services to enhance sustainable forest management in the US: moving from forest service national programmes to local projects in the Pacific Northwest

Ecosystem services are increasingly recognized as a way of framing and describing the broad suite of benefits that people receive from forests. The USDA Forest Service has been exploring use of an ecosystem services framework to describe forest values provided by federal lands and to attract and build partnerships with stakeholders to implement projects. Recently, the agency has sought placed-based applications of the ecosystem services framework to national forest management to better illustrate the concept for policymakers, managers and forest stakeholders. This framework includes describing the ecosystem services provided by forest landscapes, examining the potential trade-offs among services associated with proposed management activities, and attracting and building partnerships with stakeholders who benefit from particular services forests provide. Projects that describe objectives and outcomes using an ecosystem services framework are quickly gaining respect and could provide an optimal method of managing forests to better serve the needs of people. We describe how project-scale guidelines can be designed to address commonly recognized products such as timber and clean water, as well as critical regulating, supporting and cultural services. We present results from national programmes to forest plan assessments to project-scale applications that enhance the provision of ecosystem services and sustainable forest management at broad to local scales.