United States Forest Research Articles

Can Forest Managers Plan for Resilient Landscapes? Lessons from the United States National Forest Plan Revision Process.

The United States Forest Service, a federal agency entrusted with managing 78 M hectares of national forestlands under a broad multiple-use mandate, has seen recent shifts in policy direction emphasizing ecological restoration, consideration of climate change impacts, and a focus on managing for resilient landscapes. The process of revising the comprehensive plans guiding national forest management presents opportunities to reorient objectives, activities, and commitments toward these goals. Here we analyze case studies of three national forests that have completed the forest plan revision process since 2014: the Francis Marion National Forest in coastal South Carolina, the Kaibab National Forest in northern Arizona, and the Rio Grande National Forest in southern Colorado. We analyze plan revision participants' perspectives on the opportunities and barriers to reorienting national forest management toward resilient landscapes and the broader political, social, and institutional factors that influence these dynamics. Key opportunities included better promoting resilient landscape objectives by revising fire management guidelines, incorporating scientific data and modeling from multiple agency and non-agency partners, and building opportunities for adaptive management via long-term trust networks. Major barriers included inconsistent higher-level support for resilience objectives, an emphasis on meeting narrow quantitative performance targets, and under-investments in monitoring.

Feral Horse Space Use and Genetic Characteristics from Fecal DNA

ABSTRACTFeral horses (Equus ferus caballus) in the western United States are managed by the Bureau of Land Management (BLM) and United States Forest Service in designated areas on public lands with a goal of maintaining populations in balance with multiple uses of the landscape. Small, isolated populations can be at risk of extirpation from stochastic events and deleterious genetic effects resulting from inbreeding and reduced heterozygosity. The genetic diversity of feral horse herds is periodically monitored using blood or hair samples collected during management gathers (i.e., occasions when the herd is rounded up). We conducted a study to examine genetic characteristics of the feral horse population at the BLM Little Book Cliffs Herd Management Area (HMA) in Colorado, USA, using non‐invasively collected fecal samples. Additionally, we explored whether genotypes could be used to document space use and potential sub‐population development. We used a random sampling scheme, walking transects in sampling areas covering most of the HMA to find and collect fecal samples of all ages, except those that were deteriorating. We collected >1,800 fecal samples from across the study area in May, August, and October 2014. We then identified unique individuals using a suite of microsatellite loci. Our estimates of genetic diversity from fecal samples were higher than those reported from blood and hair samples taken during recent horse gathers, likely because our sample size and spatial distribution was larger. Genotypes revealed that some individuals were found only in certain parts of the study area and at a higher proportion than random; thus, they could be considered residents in those sampling areas. Using discriminant function analyses, we detected 5 genetic groups in the sample population, but these did not correspond to individuals in specific parts of the study area. Our results support the use of fecal DNA to augment direct observations of horse presence and could be used to detect habitat use and areas of high density. Non‐invasive techniques such as fecal DNA sampling can help managers decide whether new individuals need to be translocated to a closed population to maintain genetic diversity without the human safety and animal welfare concerns associated with gathers and invasive techniques. © 2021 The Wildlife Society.

Contemporary status, distribution, and trends of mixedwoods in the northern United States

As interest in managing and maintaining mixedwood forests in the northern United States (US) grows, so does the importance of understanding their abundance and distribution. We analyzed Forest Inventory and Analysis data for insights into mixedwood forests spanning 24 northern US states from Maine south to Maryland and westward to Kansas and North Dakota. Mixedwoods, i.e., forests with both hardwoods and softwoods present but neither exceeding 75%–80% of composition, comprise more than 19 million hectares and more than one-quarter of the northern US forest. They are most common in the Adirondack – New England, Laurentian, and Northeast ecological provinces but also occur elsewhere in hardwood-dominated ecological provinces. These mixtures are common even within forest types nominally categorized as either hardwood or softwood. The most common hardwoods within those mixtures were species of Quercus and Acer, and the most common softwoods were species of Pinus, Tsuga, and Juniperus. Although mixedwoods exhibited stability in total area during our analysis period, hardwood saplings were prominent, suggesting widespread potential for eventual shifts to hardwood dominance in the absence of disturbances that favor regeneration of the softwood component. Our analyses suggest that while most mixedwood plots remained mixedwoods, harvesting commonly shifts mixedwoods to either hardwood- or softwood-dominated cover types, but more specific information is needed to understand the causes of these shifts.

Individual fitness is decoupled from coarse‐scale probability of occurrence in North American trees

Habitat suitability estimated with probability of occurrence in species distribution models (SDMs) is used in conservation to identify geographic areas that are most likely to harbor individuals of interest. In theory, probability of occurrence is coupled with individual fitness so that individuals have higher fitness at the centre of their species environmental niche than at the edges, which we here define as ‘fitness‐centre' hypothesis. However, such relationship is uncertain and has been rarely tested across multiple species. Here, we quantified the relationship between coarse‐scale probability of occurrence projected with SDMs and individual fitness in 66 tree species native of North America. We used 1) field data of individuals' growth rate (height and diameter standardized by age) available from the United States Forest Inventory Analysis plots; and 2) common garden data collected from 23 studies reporting individual growth rate, survival, height and diameter of individuals originated from different provenances in United States and Canada. We show ‘fitness–centre' relationships are rare, with only 12% and 11% of cases showing a significant positive correlation for field and common garden data, respectively. Furthermore, we found the ‘fitness–centre' relationship is not affected by the precision of the SDMs and it does not depend upon dispersal ability and climatic breath of the species. Thus, although the ‘fitness–centre' relationship is supported by theory, it does not hold true in nearly any species. Because individual fitness plays a relevant role in buffering local extinction and range contraction following climatic changes and biotic invasions, our results encourage conservationists not to assume the ‘fitness–centre' relationship when modelling species distribution.

Distribution of Competition Potential Between Native Ungulates and Free‐Roaming Equids on Western Rangelands

ABSTRACTFree‐roaming equids (i.e., feral horses [Equus caballus] and burros [Equus asinus]) are widely distributed and locally abundant across the rangelands of the western United States. The 1971 Wild Free Roaming Horse and Burro Act (WFRHBA) gave the Bureau of Land Management (BLM) and United States Forest Service (USFS) the legal authority to manage these animals on designated public lands. To fulfill this responsibility, federal agencies established an Appropriate Management Level (AML), defined as the number of horses or burros that can be sustained on a given management unit under prevailing environmental conditions and land uses. Although the WFRHBA specifies that feral equids must be managed in ecological balance with other land uses, including conservation of native wildlife, population control measures such as gathers, contraception, and adoptions have failed to keep pace with intrinsic growth rates. Over 80% of federally managed herds currently exceed prescribed population levels, making the potential for competition between native ungulates and feral equids a growing concern among state wildlife agencies. Mule deer (Odocoileus hemionus), pronghorn (Antilocapra americana), elk (Cervus canadensis), and bighorn sheep (Ovis canadensis) are of ecological and economic value to the states where they occur, and all exhibit some degree of distributional, habitat, or dietary overlap with horses or burros. Notwithstanding the scale of the problem, to date there have been no range‐wide assessments of competition potential among native and feral ungulates for space, forage, or water. To address this need, we compiled demographic, jurisdictional, and species occurrence data collected from 2010–2019 by federal and state agencies. We used these data to map the distributions of 4 native ungulate species across federal equid management units (FEMUS) in 10 western states (n = 174). We then made within‐state rankings of the 50 units that were ≥2 times over AML and encompassed ≥3 native ungulates. Collectively, FEMUs covered approximately 225,000 km2, representing 18% of all BLM and USFS lands in affected states. Each FEMU supported ≥1 native ungulate and 14% contained all 4. The degree of overlap between native and feral species varied by state, ranging from <1% for mule deer in Montana, to 40% for bighorn sheep in Nevada. Oregon had the largest proportion of units that supported all 4 native ungulates (58%), whereas Montana and New Mexico had the fewest equids, but all populations were over target densities. Despite the perception that the problem of equid abundance is limited to the Great Basin states, high intrinsic growth rates and social constraints on management practices suggest all affected states should monitor range conditions and native ungulate demography in areas where forage and water resources are limited and expanding equid populations are a concern. © 2021 The Wildlife Society.

Increasing Synchronous Fire Danger in Forests of the Western United States

AbstractWidespread fire activity taxes suppression resources and can compound wildfire hazards. We examine the geographic synchronicity of fire danger across western United States forests as a proxy for the strain on fire suppression resource availability. Interannual variability in the number of days with synchronous fire danger, defined as fire weather indices exceeding the local 90th percentile across ≥40% of forested land, was strongly correlated (r = 0.85) with the number of days with high strain on national fire management resources. A 25‐day increase in the annual number of days with synchronous fire danger was observed during 1979–2020. Climate projections show a doubling of such days by 2051–2080. Such changes will escalate the likelihood of years with extended periods of synchronous fire danger that have historically strained suppression efforts and contributed to additional burned area, therein requiring additional management strategies for coping with anticipated surges in fire suppression demands.

Region-wide assessment of fine-scale associations between invasive plants and forest regeneration

Invasive plants are widely spread throughout the forests of the southern United States (US) and are expected to rapidly increase their distributional ranges over the next few decades. Multiple studies have shown that invasive plants pose great challenges to forest regeneration at local spatial scales; however, little is known about how those local-scale impacts of invasive plants may collectively influence forest regeneration at a regional scale. In this study, we hypothesized that invasive plants influence forest regeneration across southern US forests by altering tree seedling and sapling abundance and diversity. We used a total of 52,690 southern US forestland plots surveyed between 2015 and 2019 by the Forest Inventory and Analysis (FIA) program of the US Department of Agriculture Forest Service. We compiled presence/absence data from 16 major invasive plant taxa and calculated the number, richness, and diversity of seedlings and saplings for all major tree species present in the dataset. We used Generalized Linear Models to examine the relationship of the selected invasive plants to tree seedlings and saplings. We then used principal component analysis to evaluate whether negative relationships appeared to be related to niche differences. We found that the presence of invasive plants generally was negatively associated with tree seedling and sapling abundance, and that these negative interactions appeared to be independent of niche associations. Moreover, fast-growing hardwood tree species had the fewest negative species-wise associations with invasive plants, which suggests that the influence of plant invasions on forest regeneration may be partly mediated by the functional traits of regenerating tree species. We also found that the invasive plants evaluated in this study differentially influenced seedling versus sapling abundance and diversity, which could have complex implications for decision-making related to forest management strategies. Ultimately, the potential impact of these invasive plants on tree regeneration is likely to hamper the sustainable management of southern US forests (natural and managed) by the reduction of extant biodiversity. Thus, invasive plants should be incorporated into management strategies to help ensure the persistence of native forest communities and the ecological services they provide.

Long-term effects of catastrophic wind on southern US coastal forests: Lessons from a major hurricane.

Threats posed by windstorms are an increasing concern to forest managers in the southern United States (US). Studies suggest that the southern US will experience an increase in the occurrence as well as the intensity of windstorms, such as hurricanes, in the future. However, forest managers may have difficulty preparing for this future because there is limited understanding of how windstorms affect the structure and composition of forests over the long term. In this study, we evaluated the impacts of Hurricane Ivan, which made landfall in September 2004 near Gulf Shore, Alabama, impacting forests in the western Florida Panhandle and southwestern Alabama. We acquired the United States Department of Agriculture Forest Inventory and Analysis (FIA) plot data available for the period from 2002 to 2018 for the Ivan-affected area and classified the plots into 4 categories: (1). ND (No Disturbance), (2). NDBH (No Disturbance but Harvested), (3). ID (Disturbance caused by Hurricane Ivan), and (4). IDAH (Disturbance caused by Hurricane Ivan and Harvested). The plots that were damaged by Hurricane Ivan (ID and IDAH plots) had significantly (α = 0.05) (1) higher basal area, (2) higher quadratic mean diameter and height, (3) more diverse tree species composition (species richness and Shannon diversity index), (4) denser stocking of seedling and saplings, (5) lower proportion of dead trees or saplings, and (6) higher live aboveground biomass than the plots that were not damaged by the hurricane (ND and NDBH plots). Diverse stands were not necessarily more windstorm resistant. Species diversity in the overstory may not improve forest resistance to hurricane damage but may improve its resilience following the hurricane. The study suggests that managing stand structure through density management and stand improvement could be critical to windstorm resilience and resistance in the southern US forests.

Institutional changes drive land use transitions on rangelands: The case of grazing on public lands in the American West

Livestock grazing on natural rangeland vegetation is one of the most extensive land uses on the earth, with important implications for livelihoods, food security and the environment. Factors such as population growth and urban development, a shift from resource-based to service-based economies, and intensification in the livestock industry change the extent and practice of grazing worldwide. We investigated how and why livestock grazing on public lands changed since 1940 in the High Divide region of the Northern Rocky Mountains through a detailed analysis of United States Forest Service (USFS) rangeland management records. Based on a 90-year land use history, we process-traced the proximate causes of changes in grazing, identified the decision-makers, and statistically tested which underlying factors were associated with changes in grazing. The forage annually consumed by livestock in our study area declined by 62% since 1940, the equivalent of about 33,000 fewer cows grazing on public lands for a three-month summer period. Livestock grazing was closed on 21% of the total allotment area. The reductions in grazing were mainly caused by land management and policy factors: evaluations of range condition (27%), carrying capacity estimates (21%) and legal and administrative requirements (14%) derived from the Endangered Species Act (ESA) and National Environmental Protection Act (NEPA). The socio-economic causes of ranch economics (14%) and amenity migration (8%) were comparatively small. Overlap with wilderness and proximity to amenity towns were significant spatial predictors of reductions in grazing. The fate of publicly-owned but privately-used rangelands largely depends on institutions that are able to reconcile the competing values and demands that influence how they are managed.

"Greed for Land": W. W. Ashe and the Environmental Roots of the 1921 Flood in Central Texas

"Greed for Land":W. W. Ashe and the Environmental Roots of the 1921 Flood in Central Texas Char Miller (bio) Click for larger view View full resolution W. W. Ashe circa 1926. Photograph courtesy of Will Ashe Bason. [End Page 62] In 2010–11, the San Antonio River Authority (SARA) spent an estimated $4 million retrofitting the Olmos Dam (built between 1925 and 1927); workers drilled sixty-eight top-to-bottom holes in the dam and in each inserted cable tendons that were then anchored in bedrock, tightened, and sealed. This project was a consequence of floods in 1998 and 2002, during which a worrisome volume of water had roared down Olmos Creek, which at thirty-two square miles serves as the upper reaches of the San Antonio River—its headwaters. Each time, the floodwaters had piled up behind the aging detention dam and submerged US 281, San Antonio's vital north-south highway. Concerned about the dam's stability, engineers also were struck by how fast the rampaging flow had moved downstream. The two concerns were related and directly connected to US Route 281: it is a key thoroughfare for those commuting daily from their homes in the northern suburbs to work in the downtown core (and beyond). These commuters live in subdivisions that extend along and radiate out from the highway, and they shop in the many malls and strip centers platted at each exit. By the late 1990s, Olmos Creek's upper basin had been built out and what once had been a landscape of oaks, junipers, and grassland had been made impervious with every roof, gutter, street, and parking lot. These intertwined developments accelerated the movement [End Page 63] of water across this concertized terrain, forcing SARA to retrofit the Olmos Dam.1 W.W. Ashe (1872–1932), who had been a witness to the 1921 flood that had hammered San Antonio and led to the construction of the Olmos Dam in the first place, would not have been surprised that early twenty-first century engineers discovered there was a tight link between upstream conditions and downstream dangers. That is precisely what he had warned would happen if the city's public officials and business elite—the dam's lead advocates—did not better manage the environment north of where the flood-retention infrastructure was to be built. Ashe was not concerned about concrete, but cattle. Yet for all their differences, the inanimate building material and the four-legged ruminant had this in common: they flattened the land. As a scientist and researcher, Ashe, who was working for the United States Forest Service in 1921, had been studying the interplay between high country watersheds and valley communities that depended on them since the 1890s.2 He had begun this work while employed by the North Carolina Geological Survey, under whose aegis he examined how deforestation and overgrazing contributed significantly to the frequency and intensity of floods in the Appalachian Mountains. He assessed these and other anthropogenic factors in an 1897 path-breaking volume, Timber Trees and Forests of North Carolina, which he co-authored with forester Gifford Pinchot and who as first chief of the Forest Service later hired Ashe to work for the federal agency.3 He noticed that degraded land increased erosion, and that this erosion filled streams with silt. When heavy rains pounded cutover mountains and chewed-up hills, creeks quickly filled with debris-driving floodwaters, a churning force that carried uprooted trees and bushes, boulders, rocks, and gravel. This dangerous energy plowed up farmlands, undercut bridges, and slammed into river towns and cities. To combat the damage that such floods routinely produced in the Appalachians from New England to the Deep South, grassroots organizations championed legislation that would enable the federal government to purchase denuded land from willing sellers with the goal of regenerating forest and grass cover. After more than a decade of debate, activists in the North and South managed to secure congressional approval for what is known as the Weeks Act (1911). One crucial element of this bill was [End Page 64] the creation of the National Forest Reservation Commission, which would determine which...

Estimating the Potential for Forest Degradation in the Eastern United States Woodlands from an Introduction of Sudden Oak Death

Research Highlights: This research identified areas of the eastern United States forests that may be at particular risk from Sudden Oak Death (SOD) if it becomes established in the region. The highest suitability for SOD occurs where there are both species at risk of serious infection and species that could spread SOD to new hosts. Background and Objectives: SOD, caused by Phytophthora ramorum, can cause serious damage to forests. Although SOD is not believed to exist in the wild in the eastern United States, the presence of potential P. ramorum hosts in the area has led to questions about the potential for its establishment there. The present project expanded on previous efforts by examining both the possibility and potential consequences of P. ramorum establishment based on the presence of suitable hosts. Materials and Methods: We developed a map of the potential severity of tree loss that could result from a P. ramorum establishment in the eastern United States as well as a habitat suitability index based on the density of P. ramorum susceptible and spreader host species. We also implemented a connectivity analysis method for determining patches important to the spread of P. ramorum in the Great Smoky Mountains National Park. Results: The Ozarks and Appalachians both had a high potential severity of infection due to their high percentage of susceptible species, but the Appalachians had a higher overall level of risk due to the presence of more spreader tree species in the area. Connectivity analysis in the Great Smoky Mountains National Park identified patches likely to be particularly important to P. ramorum spread. Conclusions: Analysis of the presence of potential P. ramorum hosts in the eastern United States identified suitable conditions for SOD establishment there, particularly in the Appalachians. Techniques developed in this research can identify critical areas for SOD spread at both landscape and regional scales.

Warmer and Drier Fire Seasons Contribute to Increases in Area Burned at High Severity in Western US Forests From 1985 to 2017

AbstractIncreases in burned area across the western United States (US) since the mid‐1980s have been widely documented and linked partially to climate factors, yet evaluations of trends in fire severity are lacking. Here we evaluate fire severity trends and their interannual relationships to climate for western US forests from 1985 to 2017. Significant increases in annual area burned at high severity (AABhs) were observed across most ecoregions, with an overall eightfold increase in AABhs across western US forests. The relationships we identified between the annual fire severity metrics and climate, as well as the observed and projected trend toward warmer and drier fire seasons, suggest that climate change will contribute to increased fire severity in future decades where fuels remain abundant. The growing prevalence of high‐severity fire in western US forests has important implications to forest ecosystems, including an increased probability of fire‐catalyzed conversions from forest to alternative vegetation types.

The Genetic Diversity of Cranberry Crop Wild Relatives, Vaccinium macrocarpon Aiton and V. oxycoccos L., in the US, with Special Emphasis on National Forests.

Knowledge of the genetic diversity in populations of crop wild relatives (CWR) can inform effective strategies for their conservation and facilitate utilization to solve agricultural challenges. Two crop wild relatives of the cultivated cranberry are widely distributed in the US. We studied 21 populations of Vaccinium macrocarpon Aiton and 24 populations of Vaccinium oxycoccos L. across much of their native ranges in the US using 32 simple sequence repeat (SSR) markers. We observed high levels of heterozygosity for both species across populations with private alleles ranging from 0 to 26. For V. macrocarpon, we found a total of 613 alleles and high levels of heterozygosity (HO = 0.99, HT = 0.75). We also observed high numbers of alleles (881) and levels of heterozygosity (HO = 0.71, HT = 0.80) in V. oxycoccos (4x). Our genetic analyses confirmed the field identification of a native population of V. macrocarpon on the Okanogan-Wenatchee National Forest in the state of Washington, far outside the previously reported range for the species. Our results will help to inform efforts of the United States Department of Agriculture Agricultural Research Service (USDA-ARS) and the United States Forest Service (USFS) to conserve the most diverse and unique wild cranberry populations through ex situ preservation of germplasm and in situ conservation in designated sites on National Forests.

Estimating Terrain Slope from ICESat-2 Data in Forest Environments

The global digital elevation measurement (DEM) products such as SRTM DEM and GDEM have been widely used for terrain slope retrieval in forests. However, the slope estimation accuracy is generally limited due to the DEMs’ low vertical accuracy over complex forest environments. The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) mission shows excellent potential for slope estimation because of the high elevation accuracy and unique design of beam pairs. This study aimed to explore the possibility of ICESat-2 data for terrain slope retrieval in the United States forests. First, raw ICESat-2 data were processed to obtain accurate ground surfaces. Second, two different methods based on beam pairs were proposed to derive terrain slopes from the ground surfaces. Third, the estimated slopes were validated by airborne LiDAR-derived slopes and compared with SRTM-derived slopes and GDEM-derived slopes. Finally, we further explored the influence of surface topography and ground elevation error on slope estimation from ICESat-2 data. The results show that the ground surface can be accurately extracted from all scenarios of ICESat-2 data, even weak beams in the daytime, which provides the basis for terrain slope retrieval from ICESat-2 beam pairs. The estimated slope has a strong correlation with airborne LiDAR-derived slopes regardless of slope estimation methods, which demonstrates that the ICESat-2 data are appropriate for terrain slope estimation in complex forest environments. Compared with the method based on along- and across-track analysis (method 1), the method based on plane fitting of beam pairs (method 2) has a high estimation accuracy of terrain slopes, which indicates that method 2 is more suitable for slope estimation because it takes full advantage of more ground surface information. Additionally, the results also indicate that ICESat-2 performs much better than SRTM DEMs and GDEMs in estimating terrain slopes. Both ground elevation error and surface topography have a significant impact on terrain slope retrieval from ICESat-2 data, and ground surface extraction should be improved to ensure the accuracy of terrain slope retrieval over extremely complex environments. This study demonstrates for the first time that ICESat-2 has a strong capability in terrain slope retrieval. Additionally, this paper also provides effective solutions to accurately estimate terrain slopes from ICESat-2 data. The ICESat-2 slopes have many potential applications, including the generation of global slope products, the improvement of terrain slopes derived from the existing global DEM products, and the correction of vegetation biophysical parameters retrieved from space-borne LiDAR waveform data.

Demographic shifts in eastern US forests increase the impact of late‐season drought on forest growth

While forest communities are changing as a result of global environmental change, the impacts of tree species shifts on ecosystem services such as carbon storage are poorly quantified. In many parts of the eastern United States (US), more xeric‐adapted oak‐hickory dominated stands are being replaced with mesic beech‐maple assemblages. To examine the possible impacts of this ongoing change in forest composition, we investigated how two wide‐ranging and co‐occurring eastern US species – Acer saccharum (sugar maple) and Quercus alba (white oak) – respond to interannual climate variability. Using 781 tree cores from 418 individual trees at 18 locations, we found late‐growing season drought reduced A. saccharum growth more than that of Q. alba. A gradient in the growth reduction across latitude was also found in A. saccharum, where southern populations of A. saccharum experienced greater reductions in growth during drought. Drought had a legacy effect on growth for both species, with drought occurring later in the growing season having a larger legacy effect. Consequently, as forests shift from oak to maple dominance, drought in the later part of the growing season is likely to become an increasingly important control on forest productivity. Thus, our findings suggest that co‐occurring species are responding to environmental conditions during different times in the growing season and, therefore, the timing of drought conditions will play an important role in forest productivity and carbon sequestration as forest species composition changes. These findings are particularly important because the projected increases in potential evapotranspiration, combined with possible changes in the seasonality of precipitation could have a substantial impact on how tree growth responds to future climatic change.

Deterioration Of Lipid Metabolism Despite Fitness Improvements In Wildland Firefighters

Wildland fire suppression presents a working environment that often exceeds an energy expenditure of 20 MJ/day. Despite high levels of chronic physical exertion, we have noted maladaptive alterations in adiposity and blood lipids in a small cohort of wildland firefighters (WLFF) over a short 3-month season. PURPOSE: To determine changes in clinical health metrics and serum lipids resulting from 5 months of seasonal wildland fire suppression. METHODS: We recruited 79 WLFF (72 males and 7 females from six crews (5 Hotshot crews, 1 Initial Attack crew) based in MT and CA and conducted a pre- and post-season observational study. After an overnight fast, nude body mass, blood pressure (BP), grip strength, and a step test (~VO2=20.7 mL/kg/min) for heart rate (HR) steady state were recorded. Blood samples were collected and analyzed for serum total cholesterol (CHOL), high density lipoprotein (HDL), low density lipoprotein (LDL), very low-density lipoprotein (VLDL), and triglycerides (TRIG). A 2-tailed dependent t-test was used to compare pre- and post-season values. Statistical significance was established at p<0.05. RESULTS: Body mass was increased (pre 77.4±9.7 vs post 78.4±9.5 kg, p<0.01). Systolic and diastolic BP decreased (pre 133±13/76±10 vs post 128±14/73±9 mmHG, p<0.001 and 0.05, respectively). Grip strength remained unchanged (pre 56.3±10.7 vs post 56.3±11.4 kg, p>0.05). There was a decrease in the HR response during the step test (pre 102±13 vs post 96±9 BPM, p<0.001). Serum CHOL and LDL did not change over the season (p>0.05). In contrast, serum TRIG (pre 73±35 vs post 92±55 mg/dl, p<0.0001) and VLDL (pre 14±7 vs post 18±11 mg/dl, p<0.0001) were significantly increased by the end of the season, p<0.001. Similarly, HDL was significantly reduced (pre 68±15 vs post 64±13 mg/dl), corresponding to an increase in the TC/HDL ratio (pre 1.2±0.8 vs post 1.6±1.3 (p<0.0001). CONCLUSIONS: Despite favorable changes in BP and aerobic fitness, there were maladaptive changes in serum lipids that occurred in conjunction with an increase in body mass. Further studies should explore the influence of diet, mental/emotional stress, and/or smoke exposure on the mechanisms responsible for the dysregulation of lipid metabolism in WLFF. Supported by the United States Forest Service, National Technology and Development Program

Assessment of Structural Value for Atrush Forest تقییم القیمة الترکیبیة لغابات أتروش

Using of Atrush forest as study site, to quantity the forest structure, environmental services and economic returns from the forest, located in the northern part of the Kaliqeyamat mountain range and the eastern part of the heights of the kaneMazi, while it is bordered by the western part of the center of Sub-District Atrush and the southern part is bordered by the Sheikhan District (Ain Sofni), which is within latitude (36°49'), (36°53'), south and longitude (43°17'), (43°27') north and at a height ranging from (669-1017) m, above sea level. The total area of forest (1415) km², and content more the trees of (Pinus brutia), (Pinus pinea), (Quercus ajelops), (Quercus infectoria), (Platanus orientalis) and (Ficus carica) as well as shrubs (Crataegus saligna), (Junipours occidentalis), (Salix babylonica) and (Prunus amygdalus), species grown naturally, the pine species most common type of coverage of these species is estimated at approximately (27.58%). Assessing the forest structure provides a picture of current extent and condition of Atrush forest. The data collected for forest sent to the United States Forest Service (USFS) to utilized in the i-tree Eco-program(http://www.epa.gov/airquality/benmap/index.htm). The result of this study indicated that carbon storage with in tree species were varying. In addition to that only seven have stored (20.51) tons of carbon, all other tree species had less than the amount. Understanding the species grown in the site, number of per hectare and fast-growing species provides the information needed for management and utilization of Atrush forest.

Using Satellite Imagery to Evaluate Bark Beetle-Caused Tree Mortality Reported in Aerial Surveys in a Mixed Conifer Forest in Northern Idaho, USA

Bark beetles cause significant tree mortality in western North America. The United States Forest Service coordinates annual insect and disease surveys (IDS) by observers in airplanes to map and quantify the tree mortality caused by beetles. The subjective nature of these surveys means that accuracy evaluation is important for characterizing uncertainty. Furthermore, the metric reported for quantifying tree mortality recently changed (2012–2018 depending in region) from killed trees per acre to percent tree mortality within damage polygons, posing challenges for linking older and newer records. Here we evaluated IDS severity estimates in a beetle-affected forest in northern Idaho, USA using fine-resolution satellite imagery, which permitted greater areal coverage than field data. We first used well-established methods to map beetle-caused tree mortality in two WorldView-2 (WV2) images with a high accuracy relative to field observations. Trees-per-acre measurements within collocated IDS polygons were then converted to percent mortality using three methods and evaluated with the WV2 maps. The overall accuracies for the three methods ranged from 35–38% (for methods that used five percent-mortality classes) and 49–56% (three classes). When IDS and WV2 estimates of mortality severity that were within ±15% of each other were considered accurate, overall accuracies were 71–78%. Within the aerial survey damage polygons, the total mortality area tended to be overestimated relative to WV2. WV2 imagery identified ~50% more mortality across the study region compared with the IDS methods, with most of the difference occurring where damage was low severity or in wilderness areas. Severity of Douglas-fir beetle-caused tree mortality was estimated the most accurately, whereas severity of mountain pine beetle-caused tree mortality was estimated the least accurately. Future studies that control for temporal ambiguity between IDS and satellite imagery, as well as IDS spatial error, might provide better assessments of IDS severity accuracy. Our study increases the usefulness of the rich aerial survey database by providing estimates of uncertainty in the IDS database of tree mortality severity.

Introducing Spatially Distributed Fire Danger from Earth Observations (FDEO) Using Satellite-Based Data in the Contiguous United States

Wildfire danger assessment is essential for operational allocation of fire management resources; with longer lead prediction, the more efficiently can resources be allocated regionally. Traditional studies focus on meteorological forecasts and fire danger index models (e.g., National Fire Danger Rating System—NFDRS) for predicting fire danger. Meteorological forecasts, however, lose accuracy beyond ~10 days; as such, there is no quantifiable method for predicting fire danger beyond 10 days. While some recent studies have statistically related hydrologic parameters and past wildfire area burned or occurrence to fire, no study has used these parameters to develop a monthly spatially distributed predictive model in the contiguous United States. Thus, the objective of this study is to introduce Fire Danger from Earth Observations (FDEO), which uses satellite data over the contiguous United States (CONUS) to enable two-month lead time prediction of wildfire danger, a sufficient lead time for planning purposes and relocating resources. In this study, we use satellite observations of land cover type, vapor pressure deficit, surface soil moisture, and the enhanced vegetation index, together with the United States Forest Service (USFS) verified and validated fire database (FPA) to develop spatially gridded probabilistic predictions of fire danger, defined as expected area burned as a deviation from “normal”. The results show that the model predicts spatial patterns of fire danger with 52% overall accuracy over the 2004–2013 record, and up to 75% overall accuracy during the fire season. Overall accuracy is defined as number of pixels with correctly predicted fire probability classes divided by the total number of the studied pixels. This overall accuracy is the first quantified result of two-month lead prediction of fire danger and demonstrates the potential utility of using diverse observational data sets for use in operational fire management resource allocation in the CONUS.

Efficacy and Nontarget Effects of Glyphosate and Two Organic Herbicides for Invasive Woody Vine Control

Mat-forming vines constitute half of invasive plant cover in eastern United States forests. Although glyphosate provides effective control, it has been garnering waning public acceptance due to its potential for harming human health and nontarget organisms, and due to the evolution of plant resistance. Since 67% of eastern Unites States forests are owned by private individuals, finding more acceptable chemical controls for invasive plants is important. Organic herbicides have been used for herbaceous weed control in agriculture. However, there have been no published studies of their efficacy in controlling woody plants or of their potential nontarget effects in natural areas. We compared the ability of two commercially available, organic herbicide formulations (pelargonic acid and cinnamon plus clove oils) against glyphosate to suppress growth of four woody vines, Akebia quinata, Euonymus fortunei, Hedera helix, and Vinca minor, in an urban woodland. We also tested whether these herbicides affected soil nematodes and the germination of moss and fern spores from soil. We found that glyphosate killed these vines after two spray treatments, but that a third treatment was needed the next year for the organic herbicides to kill or reduce vines. This reduction lasted into a third summer. We detected no herbicide effects on nematode densities and functional feeding groups, nor on abundance and species richness of moss and fern germinants. Although these organic herbicides cost 5–6.5 times more than glyphosate at dosages used, they greatly reduced these woody vines and can expand choices for chemical plant control for natural areas managers.