Eastern USA Research Articles

Poleward amplification, seasonal rainfall and forest heterogeneity in the Miocene of the eastern USA

Poleward amplification, seasonal rainfall and forest heterogeneity in the Miocene of the eastern USA

HIV incidence and mortality in transgender women in the eastern and southern USA: a multisite cohort study

Epidemiological monitoring of HIV among transgender women is minimal despite prioritisation of this group in the US National HIV/AIDS Strategy (2022-2025). We aimed to estimate HIV incidence in a multisite cohort of transgender women in the eastern and southern USA. Participant deaths were identified during follow-up; thus, we felt it was an ethical imperative to report mortality alongside HIV incidence. In this study, we established a multisite cohort across two modes: a site-based, technology-enhanced mode in six cities (Atlanta, Baltimore, Boston, Miami, New York City, and Washington, DC) and an exclusively digital mode that spanned 72 eastern and southern US cities that matched the six site-based cities based on population size and demographics. Trans feminine adults (≥18 years) who were not living with HIV were eligible and followed up for at least 24 months. Participants completed surveys and oral fluid HIV testing with clinical confirmation. We ascertained deaths through community and clinical sources. We estimated HIV incidence and mortality using the number of HIV seroconversions and deaths, respectively, divided by person-years accumulated from enrolment. Logistic regression models were used to identify predictors of HIV seroconversion (primary outcome) or death. Between March 22, 2018, and Aug 31, 2020, we enrolled 1312 participants with 734 (56%) in site-based and 578 (44%) in digital modes. At the 24-month assessment, 633 (59%) of 1076 eligible participants consented to extending participation. 1084 (83%) of 1312 participants were retained at this analysis based on the study definition of loss to follow-up. As of May 25, 2022, the cohort participants had contributed 2730 accumulated person-years to the analytical dataset. Overall HIV incidence was 5·5 (95% CI 2·7-8·3) per 1000 person-years and incidence was higher among Black participants and those living in the south. Nine participants died during the study. The overall mortality rate was 3·3 (95% CI 1·5-6·3) per 1000 person-years, and the rate was higher among Latinx participants. Identical predictors of HIV seroconversion and death included residence in southern cities, sexual partnerships with cisgender men, and use of stimulants. Participation in the digital cohort and seeking care for gender transition were inversely associated with both outcomes. As HIV research and interventions are increasingly delivered online, differences by mode highlight the need for continued community and location-based efforts to reach the most marginalised transgender women. Our findings underscore community calls for interventions that address social and structural contexts that affect survival and other health concerns alongside HIV prevention. National Institutes of Health. For the Spanish translation of the abstract see Supplementary Materials section.

Mortality and histopathology in sheepshead minnow (Cyprinodon variegatus) larvae exposed to pectenotoxin-2 and Dinophysis acuminata

Toxic species of the dinoflagellate genus Dinophysis can produce diarrheic toxins including okadaic acid (OA) and dinophysistoxins (DTXs), and the non-diarrheic pectenotoxins (PTXs). Okadaic acid and DTXs cause diarrheic shellfish poisoning (DSP) in human consumers, and also cause cytotoxic, immunotoxic and genotoxic effects in a variety of mollusks and fishes at different life stages in vitro. The possible effects of co-produced PTXs or live cells of Dinophysis to aquatic organisms, however, are less understood. Effects on an early life stage of sheepshead minnow (Cyprinodon variegatus), a common finfish in eastern USA estuaries, were evaluated using a 96-h toxicity bioassay. Three-week old larvae were exposed to PTX2 concentrations from 50 to 4000 nM, live Dinophysis acuminata culture (strain DAVA01), live cells resuspended in clean medium or culture filtrate. This D. acuminata strain produced mainly intracellular PTX2 (≈ 21 pg cell−1), with much lower levels of OA and dinophysistoxin-1.No mortality or gill damages were observed in larvae exposed to D. acuminata (from 5 to 5500 cells mL−1), resuspended cells and culture filtrate. However, exposure to purified PTX2 at intermediate to high concentrations (from 250 to 4000 nM) resulted in 8 to 100% mortality after 96 h (24-h LC50 of 1231 nM). Histopathology and transmission electron microscopy of fish exposed to intermediate to high PTX2 concentrations revealed important gill damage, including intercellular edema, necrosis and sloughing of gill respiratory epithelia, and damage to the osmoregulatory epithelium, including hypertrophy, proliferation, redistribution and necrosis of chloride cells. Tissue damage in gills is likely caused by the interaction of PTX2 with the actin cytoskeleton of the affected gill epithelia. Overall, the severe gill pathology observed following the PTX2 exposure suggested death was due to loss of respiratory and osmoregulatory functions in C. variegatus larvae.

Habitat and abundance of cetaceans in Atlantic Ocean continental slope waters off the eastern USA

This study quantifies the abundance and spatial distribution of the cetacean community occupying continental shelf edge and inner continental slope waters along the US southeast Atlantic coast. A shipboard visual line-transect survey was conducted between June and August of 2004 that included effort in waters >50m deep encompassing the shelf break and inner continental slope off the US east coast between 28°N and 38°N latitude. The abundance of nine cetacean taxa was estimated using line-transect distance analysis and an independent observer approach to correct for visibility bias. Canonical correspondence analysis was used to examine the spatial distribution of the cetaceans encountered during the survey as a function of surface temperature, surface salinity, surface fluorescence, bottom depth, and bottom slope. The abundance estimates for most species were much higher than those from a study of the area conducted in 1998. This is primarily due to increased coverage of the shelf-break region and correction for visibility bias. The multivariate analysis indicated four distinct groups of cetaceans that partitioned habitat as a function of salinity, depth, and a latitudinal gradient. These groups were associated with specific water masses and hydrographic features including mid-Atlantic shelf waters (Group I), the shelf break (Group II), mid-Atlantic slope waters (Group III), and south Atlantic slope water (Group IV). Areas where water masses converge such as the continental shelf break along the mid-Atlantic and near Cape Hatteras, North Carolina are therefore areas of both high diversity and density of cetaceans.

Human-mediated dispersal drives the spread of the spotted lanternfly (Lycorma delicatula)

The spotted lanternfly (Lycorma delicatula) is a novel invasive insect from Asia now established and spreading throughout the United States. This species is of particular concern given its ability to decimate important crops such as grapes, fruit trees, as well as native hardwood trees. Since its initial detection in Berks County, Pennsylvania in 2014, spotted lanternfly infestations have been detected in 130 counties (87 under quarantine) within Connecticut, Delaware, Indiana, Maryland, New Jersey, New York, Ohio, Virginia, and West Virginia. Compounding this invasion is the associated proliferation and widespread distribution of the spotted lanternfly’s preferred host plant, the tree-of-heaven (Ailanthus altissima). While alternate host plant species have been observed, the tree-of-heaven which thrives in disturbed and human-dominated areas (e.g., along roads and railways) is likely facilitating the population growth rates of spotted lanternfly. We simulated the population and spread dynamics of the spotted lanternfly throughout the mid-Atlantic USA to help determine areas of risk and inform continued monitoring and control efforts. We tested the prediction that spotted lanternfly spread is driven by human-mediated dispersal using agent-based models that incorporated information on its life-history traits, habitat suitability, and movement and natural dispersal behavior. Overwhelmingly, our results suggest that human-mediated dispersal (e.g., cars, trucks, and trains) is driving the observed spread dynamics and distribution of the spotted lanternfly throughout the eastern USA. Our findings should encourage future surveys to focus on human-mediated dispersal of egg masses and adult spotted lanternflies (e.g., attachment to car or transported substrates) to better monitor and control this economically and ecologically important invasive species.

Determining puma habitat suitability in the Eastern USA

Pumas (Puma concolor) were eliminated from most of the eastern USA a century ago. In the past couple of decades, their recovery in the West has increased puma dispersal into the Midwest, with some individuals even traveling to the East Coast. We combined published expert opinion data and a habitat suitability index in an analysis that identified 17 areas in the Upper Midwest, Ozarks, Appalachia, and New England that could potentially host puma populations in the future. Thirteen of these were larger than 10,000 km2 and so likely to ensure a puma population’s long-term genetic health. Further, we quantified patch size, human density, livestock density, percent public land, and a sociocultural index reflecting wildlife values for comparing patches, as well as present a summary of current legislation relevant to puma management in the East. Our work may be useful in identifying suitable areas to restore pumas based not only on the quality of their biophysical habitat, but also on social values conducive to puma-human coexistence.

Diversity and distribution of spine-bearing species of Pinnularia in eastern North America

Six species of large-celled Pinnularia Ehrenberg from lakes of eastern North America, P. dariana (A.W.F. Schmidt) Mills, P. alabamae Krammer, P. bihastata (A. Mann) R.M. Patrick, P. torta (A. Mann) R.M. Patrick, P. rexlowei sp. nov. and P. spinifera sp. nov. are investigated with light and scanning electron microscopy. All six species are shown to possess marginal spines, a trait sporadically encountered in Pinnularia and generally rare in raphid diatoms. Besides having spines, the six species differ in their frustular morphology, including appearance and position of spines. We summarize data on their ecology and distribution using a set of 702 sediment core samples from 424 lakes from eastern USA and Canada. Pinnularia rexlowei is only known from Quaternary lacustrine deposits in the State of Connecticut and from the surface and subfossil sediments of two lakes in northeastern USA. The other five species are relatively common, and at least one species of spine-bearing Pinnularia was found in 34% of studied lakes. Pinnularia dariana and P. torta reach as far north as Labrador, while P. alabamae, P. bihastata and P. spinifera were only encountered south of Canada. Pinnularia alabamae and P. spinifera are characteristic for lakes with relatively soft and slightly acidic water, while P. bihastata, P. dariana and P. torta are found in a wider range of physico-chemical conditions, including alkaline and eutrophic lakes.

Climate calibration of the Spring Index model for more accurate broad-scale first leaf predictions

Phenological models are needed for forecasting plant and ecosystem responses to climate change. Due to a lack of considering local adaptation induced variations in climatic requirements of plant species for phenological development, traditional uniform/non-spatial models that cover broad geographic regions are susceptible to systematic prediction biases. This study presents a climate calibration method that incorporates climate adaptation patterns of plant species into a widely used Spring Index (SI) First Leaf (FL) model. Multi-year (2009-2021) phenological observation data for a most frequently observed shrub species(common lilac Syringa vulgaris) and a most frequently observed tree species(red maple Acer rubrum) in the eastern USA from the USA-National Phenology Network (USA-NPN) were used to develop and validate the calibrated models. Climatic gradients defined by latitudinal temperature variations were used to predict varied climatic requirements of the populations of each species. Prior to calibration, SI FL predictions showed consistent geographic biases and yielded large prediction errors (especially for red maple, RMSE = 30 d). Calibrated SI FL predictions yielded reduced errors (e.g. RMSE = 16 d for red maple) and were freed from significant geographic biases (α = 0.05) in all cases. The calibration method accounted for both intraspecific and interspecific variations, leading to more accurate broad-scale first leaf predictions for the species tested. The climate-calibrated SI FL allows for more accurate tracking of the onset of spring over extensive geographic areas and would support spatially explicit natural resource and environmental conservation efforts under climate change.

Multiple datasets confirm range extension of the sicklefin devil ray Mobula tarapacana in the western North Atlantic Ocean off the eastern USA

Abstract The sicklefin devil ray (Mobula tarapacana) is a large, pelagic ray which is listed as Endangered by the International Union for Conservation of Nature (IUCN). Mobula tarapacana is thought to have a circumglobal, yet patchy distribution, and has not been verified extant off the eastern USA. Here, we report 180 sightings of M. tarapacana with a total of 361 individuals, collated across five datasets from aerial survey operations and incidental sightings in the waters off the US East Coast and Gulf of Mexico, between 1996 and 2022. This study extends the northern range of M. tarapacana in the Gulf of Mexico to 29°N, and in the Atlantic to 40°N. Seasonal trends were observed off the north-eastern coast of the USA, with M. tarapacana only present in the summer months. Measurements from high resolution digital aerial imagery found M. tarapacana off the New York coast to be adults and subadults with an average disc width of 268 cm (±25, range 232–316 cm). This study provides important spatial and temporal data for management, as well as informing areas for future research on M. tarapacana in the western Atlantic.

About spirals and pores: Xylariaceae with remarkable germ loci.

Based on phylogenetic analyses of a multi-gene matrix of nuITS-LSU rDNA, RPB2 and TUB2 sequences and morphology, xylariaceous species with uni- to pauciperitheciate stromata and ascospores having a spirally coiling (helicoid) germ slit are revised and reclassified, including detailed descriptions and illustrations. The genus Helicogermslita is redefined and restricted to seven species with massive, erumpent, clypeus-like carbonaceous stromata, and Rosellinia somala is combined in Helicogermslita. Within the core Xylariaceae, the poorly known Leptomassaria simplex is shown to be closely related to Anthostoma insidiosum, for which the new genus Oligostoma is established, and Anthostoma rhenanum is demonstrated to be synonymous with O. insidiosum. The new genus Albicollum, characterised by immersed ascomata and a collar of white pseudostromatic tissues surrounding the ostioles, is established for Amphisphaeria canicollis, Anthostoma chionostomum, Sordaria (= Helicogermslita) fleischhakii and Anthostoma vincensii. Anthostoma ostropoides is synomymised with Albicollum canicolle, and Al. berberidicola, Al. longisporum and Al. novomexicanum are described as new species. Rosellinia (= Helicogermslita) gaudefroyi is transferred to the new genus Spiririma. Anthostoma amoenum and Euepixylon udum, both with a poroid germ locus, are shown to be only distantly related, and An. amoenum is reclassified within the asexual genus Digitodochium. Based on phylogeny, the genus Euepixylon is treated as a synonym of Nemania. A new species, Nemania ethancrensonii, which is closely related to the two formerly accepted Euepixylon species (E. sphaeriostomum, E. udum) but strongly deviates from the morphological concept of Euepixylon and Nemania, is described from the eastern USA. The genera Anthostomelloides, Clypeosphaeria, Digitodochium, Emarcaea, Induratia, Linosporopsis, Magnostiolata, Occultitheca and Spiririma are revealed to form a morphologically heterogeneous lineage in a basal position of Xylariaceae. Anthostoma vincensii, Quaternaria simplex and Rosellinia gaudefroyi are lectotypified, and Amphisphaeria canicollis, Anthostoma amoenum, An. rhenanum, An. vincensii, Quaternaria simplex, Rosellinia gaudefroyi and Valsa insidiosa are epitypified. Keys to uni- to pauciperitheciate xylariaceous genera with sigmoid to helicoid germ slits and to species of Albicollum are provided. Citation: Voglmayr H, Tello S, Jaklitsch WM, et al. 2022. About spirals and pores: Xylariaceae with remarkable germ loci. Persoonia 49: 58-98. https://doi.org/10.3767/persoonia.2022.49.02.

Population genetics of an invasive mosquito vector, Aedes albopictus in the Northeastern USA.

The Asian tiger mosquito (Aedes albopictus) arrived in the USA in the 1980's and rapidly spread throughout eastern USA within a decade. The predicted northern edge of its overwintering distribution on the East Coast of the USA roughly falls across New York, Connecticut, and Massachusetts, where the species has been recorded as early as 2000. It is unclear whether Ae. albopictus populations have become established and survive the cold winters in these areas or are recolonized every year. We genotyped and analyzed populations of Ae. albopictus from the northeast USA using 15 microsatellite markers and compared them with other populations across the country and to representatives of the major global genetic clades to investigate their connectivity and stability. Founder effects or bottlenecks were rare at the northern range of the Ae. albopictus distribution in the northeastern USA, with populations displaying high levels of genetic diversity and connectivity along the East Coast. There is no evidence of population turnover in Connecticut during the course of three consecutive years, with consistent genetic structure throughout this period. Overall, these results support the presence of established populations of Ae. albopictus in New York, Connecticut, and Massachusetts, successfully overwintering and migrating in large numbers. Given the stability and interconnectedness of these populations, Ae. albopictus has the potential to continue to proliferate and expand its range northward under mean warming conditions of climate change. Efforts to control Ae. albopictus in these areas should thus focus on vector suppression rather than eradication strategies, as local populations have become firmly established and are expected to reemerge every summer.

Snow cover dynamics: an overlooked yet important feature of winter bird occurrence and abundance across the United States

Snow cover dynamics (i.e. depth, duration and variability) are dominant drivers of ecological processes during winter. For overwintering species, changes and gradients in snow cover may impact survival and population dynamics (e.g. facilitating survival via thermal refugia or limiting survival via reduced resource acquisition). However, snow cover dynamics are rarely used in species distribution modelling, especially for overwintering birds. Currently, we lack understanding of how snow cover gradients affect overwintering bird distributions and which functional traits drive these associations at regional and continental scales. Using observations from eBird, a global community science network, we explored the effects of snow cover dynamics on continental patterns of occurrence and counts for 150 bird species. We quantified the relative importance, species‐specific responses and trait‐based relationships of bird occurrence and abundance patterns to ecologically relevant snow cover dynamics across the United States. Snow cover dynamics were important environmental predictors in species distributions models, ranking within the top three predictors for most species occurrence (> 90%) and count (> 79%) patterns across the contiguous United States. Species exhibited a gradient of responses to snow cover from snow association to snow avoidance, yet most birds were limited by long, persistent snow seasons. Duration of winter and percent frozen ground without snow structured species distributions in the eastern USA, whereas snow cover variability was a stronger driver in the western USA. Birds associated with long, persistent snow seasons had traits associated with greater dispersal capacity and dietary diversity, whereas birds inhabiting regions with variable snow cover were generally habitat generalists. Our results suggest that various snow cover dynamics are important ecological filters of species distributions during winter. Global climate change is rapidly degrading key characteristics of seasonal snow cover. A changing cryosphere may elicit variable distributional changes for many overwintering birds, potentially accelerating range shifts and novel community assemblages.

On Pan-Atlantic cold, wet and windy compound extremes

The co-occurrence of extreme weather in geographically distinct regions can result in larger impacts than the sum of those associated with the individual events occurring in isolation. Previous work has proposed a connection between extreme cold temperatures over North America and wet and windy weather over Europe. Here, we present a systematic statistical analysis of this link, focusing on extreme occurrences in both continents. We identify wintertime cold air outbreaks (CAOs) for 38 overlapping domains over North America between 1979 and 2020 using ERA5 data. The occurrence of these regional CAOs is then matched to extreme precipitation and wind events over 6 domains in western and central Europe. We find CAOs over the eastern and central USA co-occur with more frequent wind extremes over Iberia, whilst CAOs over eastern Canada are followed by wind extremes over northern Europe and the British Isles. Precipitation extremes exhibit greater variability and typically occur prior to the peak of the CAOs. We find significant increases in Iberian and southern European precipitation extremes occurring in conjunction with CAOs over the eastern USA, consistent with what we found for wind extremes. Indeed, Iberia is one of the hotspot regions for wet and windy extremes co-occurring with CAOs in North America: depending on CAO region, the frequency of extreme precipitation and wind events over Iberia locally can more than double relative to climatology. Results indicate that the location of wet and windy European extremes substantially depends on the North American region affected by CAOs. Although pan-Atlantic extremes are associated with an enhanced upper-level jet stream, their complete dynamical description requires further investigation.

Projections of Future Air Quality Are Uncertain. But Which Source of Uncertainty Is Most Important?

AbstractUnderstanding how air pollution events may change in the future is of key importance to decision makers. Multi‐model intercomparison projects focusing on atmospheric chemistry and air quality have been performed to inform the latest IPCC assessments. Future anthropogenic emission changes have generally been the foci of such model experiments, envisaged as the dominant driver of future atmospheric composition. The latest model assessments such as AerChemMIP utilize multi‐model ensembles but also have limited individual model ensembles which permit different sources of uncertainty to be characterized. The recent study by Fiore et al. (2022, https://doi.org/10.1029/2021JD035985) specifically considers a multi‐model and multi‐member ensemble approach. It adds to the quantification of uncertainty in future projections through delineating uncertainty due to model diversity and due to internal or natural climate variability within the climate system, for mean and high PM2.5 air pollution events over the Eastern USA in the 21st century. Exploring the separate roles of internal climate variability and model diversity adds further value to the important research issue of quantifying how future anthropogenic climate change impacts air quality. Future multi‐model intercomparisons need to balance the additional knowledge gained from research into understanding multiple sources of uncertainty that can inform decision making vs. the resource costs of performing these experiments using Earth System Models with interactive chemistry.

Composition of Coriander Seed Grown in Virginia, USA

Coriander (Coriandrum sativum L.) is an aromatic member of the Apiaceae with a wide diversity of uses. Its rapid life cycle allows it to fit into different growing seasons, making it possible to grow the crop under a wide range of conditions. Even though extensive demand for this herb exists among ethnic communities, its’ production in the eastern USA is essentially non-existent. We are interested in facilitation of commercial production of this herb and to characterize its’ composition. We have previously observed that coriander can be commercially produced in Virginia but composition of coriander seed produced in Virginia (Mid-Atlantic region of the United States of America) is unknown. To remedy this situation, we conducted two experiments during 2015 and 2016 with three cultivars (‘Santo’, ‘Santo Monogerm’, and ‘Marino-Organic’). Coriander seed in this study had 7.6 and 8.7 percent oil and 17 and 15 percent protein in winter (planted in December 2015 and harvested in July, 2016) or summer crop (planted in May, 2016 and harvested), respectively whereas mean concentrations (g per 100 g) of P, K, S, Mg, Ca, and Na were 501, 830, 140, 332, 620, 10, respectively. Concentrations of B, Zn, Mn, Fe, and Cu (mg per 100 g) were 1.10, 2.71, 2.81, 8.96, and 1.29, respectively. Coriander seed in this study contained approximately 19, 63, and 17 percent total saturated, MUFA, and PUFA fatty acids, respectively. Coriander seed contained 0.179, 0.877, and 0.219 percent fructose, glucose, and sucrose, respectively. Our results indicated that coriander seed produced in Virginia has seed composition, generally, similar to that produced elsewhere.

Long-term variability in atmospheric moisture transport and relationship with heavy precipitation in the eastern USA

Long-term variability in atmospheric moisture transport and relationship with heavy precipitation in the eastern USA

Effectiveness of the Reconstructed MODIS Typical-Angle Reflectances on Forest Biomass Estimation

Multi-angle optical reflectance measurements such as those from the NASA moderate resolution imaging spectroradiometer (MODIS) are sensitive to forest 3D structures, potentially serving as a useful proxy to estimate forest structural variables such as aboveground biomass (AGB)—a potential theoretically recognized but rarely explored. In this paper, we examined the effectiveness of the reconstructed MODIS typical-angle reflectances—reflectances observed from the hotspot, darkspot, and nadir directions—for estimating forest AGB from both theoretical and practical perspectives. To gain theoretical insights, we first tested the sensitivities of typical-angle reflectances to forest AGB through simulations using the 4-scale bidirectional reflectance distribution function (BRDF) model. We then built statistical models to fit the relationship between MODIS multi-angle observations and field-measured deciduous-broadleaf/mixed-temperate forest AGB at five sites in the eastern USA, assisted by a semivariogram analysis to determine the effect of pixel heterogeneity on the MODIS–AGB relationship. We also determined the effects of terrain and season on the predictive relationships. Our results indicated that multi-angle reflectances with fewer visible shadows yielded better AGB estimates (hotspot: R2 = 0.63, RMSE = 54.28 Mg/ha; nadir: R2 = 0.55, RMSE = 59.95 Mg/ha; darkspot: R2 = 0.46, RMSE = 65.66 Mg/ha) after filtering out the effects of complex terrain and pixel heterogeneity; the MODIS typical-angle reflectances in the NIR band were the most sensitive to forest AGB. We also found strong sensitivities of estimated accuracies to MODIS image acquisition dates or season. Overall, our results suggest that the current practice of leveraging only single-angle MODIS data can be a suboptimal strategy for AGB estimation. We advocate the use of MODIS multi-angle reflectances for optical remote sensing of forest AGB or potentially other ecological applications requiring forest structure information.

Harvest and dispersal syndromes influence the probability of tree seedling establishment in the eastern United States

AbstractAimThe goal of this work was to investigate the influence of disturbance, in particular tree harvesting, on seedling establishment rates both within and beyond the range extent of individual species. In addition, we considered how disturbances differentially affect seedling establishment depending on the dispersal syndromes and shade tolerance of species.LocationThis project covers the eastern forests of the USA.Time periodData for this project extend from 1996 to 2019.Major taxa studiedTree species of the eastern USA.MethodsWe used the US Forest Service's Forest Inventory and Analysis (FIA) data for tree species of the eastern USA to investigate the influence of disturbance, the dispersal mechanism and shade tolerance of species on the establishment of seedlings. We ran generalized linear models for seedling presence/absence and the number of seedlings as the response variables. Disturbance categories were no disturbance, natural disturbance, harvest, and both harvest and natural disturbance.ResultsThe probability of seedling establishment increased in response to harvest within FIA plots but not in response to natural disturbances. Harvest increased the probability of seedling presence the most for shade‐intolerant species; however, intermediately shade‐tolerant and ‐intolerant species also increased in harvested plots. Additionally, bird‐dispersed species had a higher probability of colonizing new plots outside their range, in comparison to mammal‐dispersed or wind‐dispersed tree species.Main conclusionsOur results suggest that stand competition is an important limiting factor for seedling establishment in the dense, secondary forests of the eastern USA. Harvesting creates sizeable gaps that promote seedling establishment and species turnover. Harvesting especially facilitates the establishment of tree species with bird dispersal outside of their range. Thus, timber harvesting can be a useful management tool when the goal is to assist range shifts for certain species. We recommend that future research should include harvested plots when looking for evidence of recent tree migration.

The wild life of ticks: Using passive surveillance to determine the distribution and wildlife host range of ticks and the exotic Haemaphysalis longicornis, 2010–2021

BackgroundWe conducted a large-scale, passive regional survey of ticks associated with wildlife of the eastern United States. Our primary goals were to better assess the current geographical distribution of exotic Haemaphysalis longicornis and to identify potential wild mammalian and avian host species. However, this large-scale survey also provided valuable information regarding the distribution and host associations for many other important tick species that utilize wildlife as hosts.MethodsTicks were opportunistically collected by cooperating state and federal wildlife agencies. All ticks were placed in the supplied vials and host information was recorded, including host species, age, sex, examination date, location (at least county and state), and estimated tick burden. All ticks were identified to species using morphology, and suspect H. longicornis were confirmed through molecular techniques.ResultsIn total, 1940 hosts were examined from across 369 counties from 23 states in the eastern USA. From these submissions, 20,626 ticks were collected and identified belonging to 11 different species. Our passive surveillance efforts detected exotic H. longicornis from nine host species from eight states. Notably, some of the earliest detections of H. longicornis in the USA were collected from wildlife through this passive surveillance network. In addition, numerous new county reports were generated for Amblyomma americanum, Amblyomma maculatum, Dermacentor albipictus, Dermacentor variabilis, and Ixodes scapularis.ConclusionsThis study provided data on ticks collected from animals from 23 different states in the eastern USA between 2010 and 2021, with the primary goal of better characterizing the distribution and host associations of the exotic tick H. longicornis; however, new distribution data on tick species of veterinary or medical importance were also obtained. Collectively, our passive surveillance has detected numerous new county reports for H. longicornis as well as I. scapularis. Our study utilizing passive wildlife surveillance for ticks across the eastern USA is an effective method for surveying a diversity of wildlife host species, allowing us to better collect data on current tick distributions relevant to human and animal health.

Why are the Appalachians high? New insights from detrital apatite laser ablation (U-Th-Sm)/He dating

The timing of surface uplift across the Appalachian Mountains, Eastern USA, remains a controversial topic. Thermal history modelling, geomorphological analysis, stratigraphic analysis, and river profile analysis have all suggested the region experienced surface uplift during the late Cenozoic. This is in contrast with many low-temperature thermochronology studies, which consistently present Mesozoic dates and typically infer the landscape to be the remnant of a much older mountain belt that has been slowly exhumed following the end of rifting in the Late Triassic-Early Jurassic. Resolving a regional exhumation history of the Appalachians through traditional low-temperature thermochronology methods is difficult due to the spatial constraints of bedrock sampling, while traditional detrital river sampling has limitations underpinned by analytical issues and grain selection bias. We aim to resolve the exhumation histories of large areas across the Appalachians using detrital laser ablation apatite (U-Th-Sm)/He dating (LA-AHe). LA-AHe is a new dating approach that produces a high number of apatite (U-Th-Sm)/He ages from modern river sands to infer the low-temperature (70–40°C) exhumation history of the bedrock across a catchment. Supplementary apatite and zircon U-Pb dates were obtained to study sediment transport in each catchment and their respective bedrock geological histories. LA-AHe results show most dates to be Cretaceous (69%), with only a small Cenozoic fraction (6%), while thermo-kinematic modelling of data from four catchments can be explained by protracted Mesozoic-Cenozoic exhumation with rates ∼31–20 m/Myr. The lack of Cenozoic dates does imply the magnitude of exhumation has not been significant enough to greatly affect the apatite (U-Th-Sm)/He system, though models incorporating enhanced late Cenozoic exhumation between 2.1–1.4 km are consistent with data from three catchments. These results have implications for the study of elevated topography across passive margins and ancient orogens and highlight how laser ablation apatite (U-Th-Sm)/He dating can be effectively used to study the change of landscapes over geological timescales.