Eastern US Research Articles

Historical Plant Sales (HPS) database: Documenting the spatiotemporal history of plant sales in the conterminous U.S.

Historical horticultural plant sales influence native and nonnative species assemblages in contemporary ecosystems. Over half of nonnative, invasive plants naturalized in the United States were introduced as ornamentals, and the spatial and temporal patterns of early introduction undoubtedly influence current invasion ecology. While thousands of digitized nursery catalogs documenting these introductions are publicly available, they have not been standardized in a single database. To fill this gap, we obtained the names of all plant taxa (species, subspecies, and varieties) present in the Biodiversity Heritage Library's (BHL) Seed and Nursery Catalog Collection. We then searched the BHL database for these names and downloaded all available records. We combined BHL records with data from an encyclopedia of heirloom ornamental plants to create a single database of historical nursery sales in the US. Each record represents an individual taxon offered for sale at an individual time in a specific nursery's catalog. We standardized records to the current World Flora Online (http://worldfloraonline.org) accepted taxonomy and appended accepted USDA code, growth habit, and introduction status. We also appended whether taxa were reported as invasive in the Global Plant Invaders (GPI) data set or the Global Invasive Species Database (GISD) or regulated in the conterminous US. Lastly, we geocoded all reported publication locations. The data set contains 2,445,875 records from nurseries in at least 2795 unique locations, with the majority of catalogs published between 1890 and 1950. Nurseries were located in all conterminous states but were concentrated in the eastern US and California. We identified 19,140 unique horticultural taxa, of which 8642 matched taxa in the USDA Plants database. The USDA Plants database is limited to native and naturalized taxa in the US. Native or introduced status was listed in USDA Plants for 7018 of included taxa, while 1642 had an unknown status. The remaining 10,498 taxa are not naturalized according to USDA Plants or are of varieties of native and introduced taxa that did not match USDA Plants taxonomy. The majority of taxa in the Historical Plant Sales (HPS) database with an identified status are native (65.5%; 4596 of 7018 taxa), of which 393 taxa are reported as invasive outside of the US. Of the 2381 introduced taxa, 1103 (46.3%) are reported as invasive somewhere globally. Despite a richer pool of native taxa, most cataloged plant records with an identified status were of introduced taxa (54.1%; 1,045,684 of 1,933,925 records). Plants reported as invasive somewhere globally comprised a large portion of records with an identified status (38.7%; 747,953 of 1,933,925 records) underscoring the large role of ornamental introductions in facilitating plant invasions. The HPS database provides a consolidated and standardized perspective on the history of native, introduced, and invasive plant sales in the US. We release these data into the public domain under a Creative Commons Zero license waiver (https://creativecommons.org/share-your-work/publicdomain/cc0/). Individuals who use these data for publication may cite the associated data paper.

“No fences make bad neighbors” but markets make better ones: cap-and-trade reduces cross-border SO2 in a natural experiment

The clean air interstate rule (CAIR) was a regional cap-and-trade program announced in 2005 which covered 27 eastern US states and sought to reduce sulfur dioxide emissions from coal-fired power plants. The rule was later vacated after a court found that the non-targeted design of the program did not comply with the Clean Air Act provision to regulate interstate air pollution. Using a custom air pollution dispersion model, I calculate the interstate SO2 pollution from 493 coal-fired power plants across the United States between 1997 and 2020. In a difference-in-differences setup with plants not covered by CAIR in the control group, I estimate the treatment effect of the program on overall- and cross-border SO2 emissions and find a 24% reduction in overall emissions and reduces the risk that a plant violates air quality standards across state borders by 2–4%. I report evidence of heterogeneous treatment effects where the reduction in overall emissions attributed to CAIR is lower among plants transporting SO2 in excess of 1% of the National Air Quality Standards to another state.

Exploring the Factors Controlling the Long‐Term Trend (1988–2019) of Surface Organic Aerosols in the Continental United States by Simulations

AbstractObserved surface organic aerosols (OA) concentrations slightly increased in the western US (WUS) but significantly decreased in the eastern US (EUS) in summer, and continuously decreased in winter over the US region. To understand the driving factors for the long‐term surface OA trend, we apply a revised version of the Community Atmosphere Model version 6 with comprehensive tropospheric and stratospheric chemistry representation, considering the heterogeneous formation of isoprene‐epoxydiol‐derived secondary organic aerosols (SOAIE) and fast photolysis rate of monoterpene‐derived secondary organic aerosols (MTSOA) to diagnose the OA evolution in 1988–2019. Compared to older versions, the revised model better reproduces the climatology, seasonal cycle, and long‐term trend of surface OA as evaluated against the Interagency Monitoring of Protected Visual Environments measurements. We find the decrease in EUS summertime OA is likely attributed to the interplay between SOAIE and MTSOA. With anthropogenic emissions reduction, primary organic aerosols (POA) declined, SOAIE decreased along with sulfate, while MTSOA increased along with biogenic emissions driven by a warming climate. POA from wildfires with a significant trend of 2.9% yr−1 and considerable interannual variation of 62.8% drive the statistically insignificant but increasing WUS summertime OA, while anthropogenic POA dominates the decreasing wintertime OA in the US. Through sensitivity experiments, we find MTSOA show linear responses to the increasing monoterpenes emissions and negligible responses to NOx emissions reduction due to the mutual offsets between MTSOA components from different oxidation pathways. This study reveals the increasingly important role of MTSOA in summertime OA under a warming climate.

Implementation of trait-based ozone plant sensitivity in the Yale Interactive terrestrial Biosphere model v1.0 to assess global vegetation damage

Abstract. A major limitation in modeling global ozone (O3) vegetation damage has long been the reliance on empirical O3 sensitivity parameters derived from a limited number of species and applied at the level of plant functional types (PFTs), which ignore the large interspecific variations within the same PFT. Here, we present a major advance in large-scale assessments of O3 plant injury by linking the trait leaf mass per area (LMA) and plant O3 sensitivity in a broad and global perspective. Application of the new approach and a global LMA map in a dynamic global vegetation model reasonably represents the observed interspecific responses to O3 with a unified sensitivity parameter for all plant species. Simulations suggest a contemporary global mean reduction of 4.8 % in gross primary productivity by O3, with a range of 1.1 %–12.6 % for varied PFTs. Hotspots with damage >10 % are found in agricultural areas in the eastern US, western Europe, eastern China, and India, accompanied by moderate to high levels of surface O3. Furthermore, we simulate the distribution of plant sensitivity to O3, which is highly linked with the inherent leaf trait trade-off strategies of plants, revealing high risks for fast-growing species with low LMA, such as crops, grasses, and deciduous trees.

Pyrus calleryana extracts reduce germination of native grassland species, suggesting the potential for allelopathic effects during ecological invasion.

Invasive plant species' success may be a result of allelopathy, or the release of secondary metabolites that are harmful for surrounding plant species. Allelopathy can be mediated through the abiotic environment by chemical sorption or transformation, so the substrate on which interactions occur can lead to differential outcomes in allelopathic potential. One aggressive invader, Pyrus calleryana, has become dominant in many ecosystems throughout Eastern US, and has reduced the abundance of native species where it invades. Thus, our goal was to identify if P. calleryana had allelopathic potential by testing the impact of leaf and flower leachate on gemination of six common grassland species (three grasses and three forbs) in either sterilized sand or field collected soils. Germination of five out of six tested species was reduced by P. calleryana leaf litter, with weaker impacts from flower leachate. This suggests that allelopathy is one mechanism driving the success of P. calleryana and that allelopathic effects may change with plant phenology. For instance, P. calleryana has late leaf senescence in the fall and copious blooming in the spring that may elongate the timeframe that allelopathic inhibition can occur. Further, germination was higher in sand than in soil, suggesting that the context of the abiotic environment can mediate this relationship. In our study, two grass species that could be overabundant in restored grasslands had higher germination rates in soil than sand and one was not altered by P. calleryana suggesting that this relationship could further promote the overabundance of grass species. Taken together, P. calleryana likely inhibits the germination of native species where it invades, but there is context dependency of this relationship with both soil chemistry and seasonality.

Complex climate-mediated effects of urbanization on plant reproductive phenology and frost risk.

Urbanization can affect the timing of plant reproduction (i.e., flowering and fruiting) and associated ecosystem processes. However, our knowledge of how plant phenology responds to urbanization and its associated environmental changes is limited. Herbaria represent an important, but underutilized source of data for investigating this question. We harnessed phenological data from herbarium specimens representing 200 plant species collected across 120 years from the eastern United States to investigate the spatiotemporal effects of urbanization on flowering and fruiting phenology and frost risk (i.e., time between the last frost date and flowering). Effects of urbanization on plant reproductive phenology varied significantly in direction and magnitude across species ranges. Increased urbanization led to earlier flowering in colder and wetter regions and delayed fruiting in regions with wetter spring conditions. Frost risk was elevated with increased urbanization in regions with colder and wetter spring conditions. Our study demonstrates that predictions of phenological change and its associated impacts must account for both climatic and human effects, which are context-dependent and do not necessarily coincide. We must move beyond phenological models that only incorporate temperature variables and consider multiple environmental factors and their interactions when estimating plant phenology, especially at larger spatial and taxonomic scales.

Changing Seasonality of Annual Maximum Floods over the Conterminous US: Potential Drivers and Regional Synthesis

Understanding the flood-generating mechanisms that influence flood seasonality in a region provides information on setting up relevant contingency measures. Although former studies estimated flood seasonality at regional/continental scale, limited/no studies have investigated the climate/basin drivers that influence the changes in flood seasonality. Considering this, the current study performed two analyses: (1) estimated the changes in the seasonality of annual maximum floods (AMF) between pre- and post-1970 across Hydroclimate Data Network basins over the conterminous US, and (2) identified the predictors that influence the change in the seasonality from a set of climate and geomorphic variables. Significant changes in the AMF seasonality were noted for approximately half of the basins in the eastern US, but low to no change was found in most basins in the central/western US. We found, except in the Northeast and mid-Atlantic basins, a decrease in the seasonality index, indicating floods arriving more uniformly is typically associated with an increase in the precipitation days in basins. On the other hand, increase in the seasonality index, indicating floods occurring more concentrated in time, is typically associated with an increase in the extreme precipitation in basins. Among the basin characteristics, elevation has a more dominant role than the drainage area in changing the flood seasonality. Elevation affects the form of precipitation, particularly in the western US, because floods arrive more distributed over the year (i.e., decrease in flood seasonality index), which potentially indicates increased warming resulting in early snowmelt.

"Are we there yet?" Ten persistent hazards and inefficiencies with the use of medication administration technology from the perspective of practicing nurses.

(1) Characterize persistent hazards and inefficiencies in inpatient medication administration; (2) Explore cognitive attributes of medication administration tasks; and (3) Discuss strategies to reduce medication administration technology-related hazards. Interviews were conducted with 32 nurses practicing at 2 urban, eastern and western US health systems. Qualitative analysis using inductive and deductive coding included consensus discussion, iterative review, and coding structure revision. We abstracted hazards and inefficiencies through the lens of risks to patient safety and the cognitive perception-action cycle (PAC). Persistent safety hazards and inefficiencies related to MAT organized around the PAC cycle included: (1) Compatibility constraints create information silos; (2) Missing action cues; (3) Intermittent communication flow between safety monitoring systems and nurses; (4) Occlusion of important alerts by other, less helpful alerts; (5) Dispersed information: Information required for tasks is not collocated; (6) Inconsistent data organization: Mismatch of the display and the user's mental model; (7) Hidden medication administration technologies (MAT) limitations: Inaccurate beliefs about MAT functionality contribute to overreliance on the technology; (8) Software rigidity causes workarounds; (9) Cumbersome dependencies between technology and the physical environment; and (10) Technology breakdowns require adaptive actions. Errors might persist in medication administration despite successful Bar Code Medication Administration and Electronic Medication Administration Record deployment for reducing errors. Opportunities to improve MAT require a deeper understanding of high-level reasoning in medication administration, including control over the information space, collaboration tools, and decision support. Future medication administration technology should consider a deeper understanding of nursing knowledge work for medication administration.

Strange Storms: Rainfall Extremes From the Remnants of Hurricane Ida (2021) in the Northeastern US

AbstractOn 1 September 2021, the remnants of Hurricane Ida transformed into a lethal variant of tropical cyclone in which unprecedented short‐duration rainfall from clusters of supercells produced catastrophic flooding in watersheds of the Northeastern US. Short‐duration rainfall extremes from Ida are examined through analyses of polarimetric radar fields and rain gauge observations. Rainfall estimates are constructed from a polarimetric rainfall algorithm that is grounded in specific differential phase shift (KDP) fields. Rainfall accumulations at multiple locations exceed 1000‐year values for 1–3 hr time scales. Radar observations show that supercells are the principal agents of rainfall extremes. Record flood peaks occurred throughout the eastern Pennsylvania—New Jersey region; the peak discharge of the Elizabeth River is one of the most extreme in the eastern US, based on the ratio of the peak discharge to the sample 10‐year flood at the gaging station. As with other tropical cyclones that have produced record flooding in the Northeastern US, Extratropical Transition was a key element of extreme rainfall and flooding from Ida. Tropical and extratropical elements of the storm system contributed to extremes of atmospheric water balance variables and Convective Available Potential Energy, providing the environment for extreme short‐duration rainfall from supercells.

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.

Decoupled spatiotemporal patterns of avian taxonomic and functional diversity

Each year, seasonal bird migration leads to an immense redistribution of species occurrence and abundances,1,2,3 with pervasive, though unclear, consequences for patterns of multi-faceted avian diversity. Here, we uncover stark disparities in spatiotemporal variation between avian taxonomic diversity (TD) and functional diversity (FD) across the continental US. We show that the seasonality of species richness expectedly3 follows a latitudinal gradient, whereas seasonality of FD instead manifests a distinct east-west gradient. In the eastern US, the temporal patterns of TD and FD are diametrically opposed. In winter, functional richness is highest despite seasonal species loss, and the remaining most abundant species are amassed in fewer regions of the functional space relative to the rest of the year, likely reflecting decreased resource availability. In contrast, temporal signatures for TD and FD are more congruent in the western US. There, both species and functional richness peak during the breeding season, and species' abundances are more regularly distributed and widely spread across the functional space than during winter. Our results suggest that migratory birds in the western US disproportionately contribute to avian FD by possessing more unique trait characteristics than resident birds,4,5 while the primary contribution of migrants in the eastern US is through increasing the regularity of abundances within the functional space relative to the rest of the year. We anticipate that the uncovered complexity of spatiotemporal associations among measures of avian diversity will be the catalyst for adopting an explicitly temporal framework for multi-faceted biodiversity analysis.

Evaluating effectiveness of girdle-herbicide containment of below-ground spread of oak wilt (Bretziella fagacearum)

Oaks (Quercus spp) are one of the most important sources of timber, mast for wildlife, and ecosystem services across the eastern US. Increasingly, this genus is at risk from diseases including oak wilt, which is one of the most serious threats to oaks, caused by the fungus, Bretziella fagacearum. The upper Midwest has over 5 million ha of oak forests, much of which is on rocky glaciated soils where traditional methods of containing below-ground spread of oak wilt (e.g., vibratory plow lines) are not feasible. We evaluated an alternative containment method of girdling and herbicide (GH) of oak wilt infected trees as well as neighboring oak trees likely connected via root grafts. Our results demonstrated that GH was effective at controlling below-ground spread of oak wilt (overall success rate: 55 %). Best control was achieved when infection centers were small (≤4 newly infected trees), where GH was 81 % effective at containing oak wilt. Containment was only 29 % in larger infection centers (≥5 newly infected trees). The best predictor of success was the number of newly infected trees (p = 0.02) even when considering other factors that could dictate the size of infection centers (e.g., diameter of trees, or number of neighboring trees treated). Our results illustrate the importance of early and rapid management of oak wilt infections and offer a starting place for continued improvement of the GH methodology.

Sources of air pollution-related health impacts and benefits of radially applied transportation policies in 14 US cities

As the world becomes increasingly urbanized, growing populations are exposed to poor ambient air quality and at risk of the associated health outcomes. Urban air quality is affected both by local sources of air pollution and sources outside city borders. Policy-makers who develop air quality policies need to know whether it is most effective to focus on local policies or to spend resources fostering larger regional air quality management cooperation. Identifying the fraction of air pollution exposure from emissions as a function of distance from the city is a critical element of air quality management design. We estimate the health burden associated with exposure to fine particulate matter (PM2.5), ozone (O3), and nitrogen dioxide (NO2) from county-level anthropogenic sources in and around 14 US cities; this analysis is a test-bed to conduct future global analyses. We use adjoint sensitivities calculated from the chemical transport model GEOS-Chem, high resolution satellite-derived surface concentrations of PM2.5 and NO2, and health impact assessment methods. For the 70.2 million people living in these cities, we estimate that 27,740 PM2.5- and O3-related premature deaths and 126,600 NO2-related new asthma cases were attributable to air pollution exposure in 2011. Development within the GEOS-Chem adjoint framework enables sectoral attribution and policy analysis in addition to the rote assessment of impact. We find that 70% of deaths and nearly 100% of these asthma cases were attributable to anthropogenic emissions. There is great variability in the sources of the anthropogenically-related health impacts; within-urban emissions make up 5% in Austin to 56% in Los Angeles and Phoenix (median: 31%) of urban premature deaths and 18% in Austin to 82% in Los Angeles (median: 59.5%) of new asthma cases, with the remaining portions attributable to emissions from outside the urban area. For each city, we estimate the air quality related health benefits associated with the adoption of a vehicle-miles-traveled fee in that city and in multiple spatial regions surrounding the city. The findings suggest that the proportion of urban air pollution that is regional is greater for premature deaths than new asthma cases and for the eastern US than the western US.

Projected increases in wildfires may challenge regulatory curtailment of PM2.5 over the eastern US by 2050

Abstract. Anthropogenic contribution to the overall fine particulate matter (PM2.5) concentrations has been declining sharply in North America. In contrast, a steep rise in wildfire-induced air pollution events with recent warming is evident in the region. Here, based on coupled fire–climate–ecosystem model simulations, summertime wildfire-induced PM2.5 concentrations are projected to nearly double in North America by the mid-21st century compared to the present. More strikingly, the projected enhancement in fire-induced PM2.5 (∼ 1–2 µg m−3) and its contribution (∼ 15 %–20 %) to the total PM2.5 are distinctively significant in the eastern US. This can be attributed to downwind transport of smoke from future enhancement of wildfires in North America to the eastern US and associated positive climatic feedback on PM2.5, i.e., perturbations in circulation, atmospheric stability, and precipitation. Therefore, the anticipated reductions in PM2.5 from regulatory controls on anthropogenic emissions could be significantly compromised in the future in the densely populated eastern US.

Racial and Economic Stratification on Campus: The Relationship between Luxury Residence Halls, Race, and Academic Outcomes

Racial and Economic Stratification on Campus:The Relationship between Luxury Residence Halls, Race, and Academic Outcomes Joshua Travis Brown (bio), Fred Volk (bio), and Joseph M. Kush (bio) Residence hall design has remained an important topic for higher education professionals, but recently it has garnered attention from audiences beyond the postsecondary sector, including policymakers, donors, and media. In the competitive realm of enrollment management, luxury residence hall designs that emphasize high-end amenities and private rooms are vital in attracting certain prospective students (McClure, 2019). The design of luxury residence halls has created tension between the ideals of equitable educational experiences and increased competition to attract enrollment, as such facilities are often priced beyond the financial reach of students whose presence is essential to creating a diverse educational experience for all students. Rather than creating a more diverse environment, residence hall design has been shown to promote racial and economic stratification in living spaces (Foste, 2021). One form of racialized pattern in student housing is homophily, which is the grouping of students by race or class that permits (or limits) opportunities to interact with persons "like me" (McPherson et al., 2001). Yet, interacting with others of a similar race and economic background has been shown to result in better academic outcomes (Brown et al., 2019). Some researchers found residence hall design played no role in college experiences (Bronkema & Bowman, 2017), while others found isolating designs to be less conducive to flourishing and associated with poorer academic outcomes for Black students when examining Black/White differences (Brown et al., 2019). As university leaders face pressures to increase enrollment, some have allocated millions of dollars to attracting students using a new type of luxury residence hall design—hybrid luxury—that combines high-end amenities and high socialization design (Cramer, 2021; Eligon, 2013). While hybrid luxury halls emphasize added amenities such as coffee lounges, co-working spaces, and exclusive resident-only fitness studios, they also incorporate certain design elements to strategically increase patterns of student socialization. What remains unknown is (a) how emerging hybrid luxury designs may be associated with academic outcomes and (b) whether student academic outcomes differed in other forms of residence hall designs conditioned on race and homophily [End Page 108] opportunity. The focus of this work takes up these two questions. METHOD Data used in this study were drawn from archival records of a large, predominantly white institution in the Eastern US. We restricted the sample to first-semester undergraduate students and further eliminated NCAA athlete students, international students, or persons 21 years of age or older. This resulted in a sample size retrieved over seven years of 17,640 incoming first-year students. See Table 1 for demographic details of the full sample. First-semester GPA was the outcome measure for analyses, while covariates included high school GPA (a predictor of first-semester GPA) and estimated family contribution (EFC; a measure of household ability to contribute to college costs calculated from the FAFSA). Three distinct residence hall architectures were examined (i.e., traditional corridor, suite, and hybrid luxury) with a differentiated price range of $3,400 between the least and most expensive designs. Four racial/ethnic categories were included in the study (i.e., White, Black, Hispanic, and Asian American) and used to calculate homophily opportunity for each residence hall based on the percentage of residents with racial similarities. For example, if a student indicated their race was Black, their calculated homophily opportunity was equivalent to the percentage of Black students in their residence hall. We used OLS regression to assess two basic models with first-semester academic performance as the outcome. Based on prior research, we included race, residence hall design, and homophily opportunity as our focal predictors (Brown et al., 2019). The two-model approach permits an incremental examination of complex social factors where each model includes controls for high school academic performance and economic status. The first model included two residence hall designs and controlled for economic status to examine fundamental gaps in the literature. The second model considers three categories of residence hall design to examine how hybrid luxury designs may be associated with academic outcomes and whether academic outcomes differed in other forms...

Do forest health threats affect upland oak regeneration and recruitment? Advance reproduction is a key co-morbidity

We analyzed national forest inventory data collected from circa 2000–2018 across 37 states in the eastern United States to better understand the influence of forest health related canopy disturbances on the regeneration and recruitment dynamics of upland oaks (Quercus). We found low levels of oak recruitment across all disturbance types examined but limited evidence of any direct effects from the type of disturbance on the population of regenerating oaks. The general lack of differences in oak regeneration response between forest health disturbances and disturbances caused by harvested or non-disturbed plots does not indicate that the effects of forest health disturbances were benign, however. Instead, low level of oak recruitment across all disturbance types highlights the pervasiveness of the trend of shifting composition in once oak-dominated forests where oak is absent or sparse in the regeneration layer. Our results show that oak recruitment was higher when oak was present as advance reproduction prior to disturbance from any cause examined. Collectively, these results lead us to conclude that the widespread inadequacy of oak advance reproduction in mature oak-dominated forests is the prevailing threat to oak forest health and sustainability. We suggest the status of advance reproduction be treated as a co-morbidity when weighing the risk and potential outcomes from other threats to upland oak forests in the eastern United States.

Changes in bark properties and hydrology following prescribed fire in Pinus taeda and Quercus montana

AbstractIn the eastern United States, the use of prescribed fire as a silvicultural technique to manage for desirable upland tree species is increasing in popularity. Bark physical properties such as thickness, density, and porosity have known associations with fire tolerance among species. These physical properties simultaneously influence rainfall interception and canopy storage and thus are of interest across a range of disciplines. Furthermore, while these characteristics are innate to a species, it is unknown whether repeated exposure to fire facilitates physical change in bark structure and whether these changes are consistent among species. To answer these questions, bark samples were collected from mature pine (Pinus taeda L.) and oak (Quercus montana Willd.) trees from sites across the Bankhead National Forest in Alabama, USA under three different burn regimes: 3‐year cycle, 9‐year cycle, and no fire. Samples were analysed in the laboratory for bulk density, porosity, water storage capacity, and hygroscopicity (the amount of atmospheric water vapour absorbed by bark during non‐rainfall conditions). Drying rates of saturated samples under simulated wetting conditions were also assessed. Oak bark had higher bulk density, lower porosity, and dried slower than pine bark. Interestingly, bark from both species had lower bulk density, higher porosity, greater water storage capacity, and dried faster in stands that were burned every 3 years compared to other fire regimes (p < 0.001). In summary, this study demonstrates that prescribed fire regimes in an eastern US forest alter bark structure and thus influence individual tree control on hydrological processes. The increase in bark water storage capacity, coupled with faster bark evaporation times may lead to less water inputs to the forest floor and drier overall conditions. Further investigation of this fire‐bark‐water feedback loop is necessary to understand the extent of these mechanisms controlling landscape‐scale conditions.

Impacts of shifting phenology on boundary layer dynamics in North America in the CESM

Plant phenology modulates water and energy exchanges between the biosphere and the atmosphere and therefore influences planetary boundary layer (PBL) dynamics. Here we conduct a modeling experiment using the Community Earth System Model version 2, where plant phenology is prescribed based on satellite climatology in the control experiment. We then shift the timing of vegetation green-up and senescence in North America by one month earlier and later and investigate how shifting phenology could influence land-atmosphere interactions. Altering plant phenology modifies boundary layer fluxes through both direct influences on evapotranspiration and absorbed solar radiation and indirect effects through changes in low cloud fraction. The prescribed shift in phenology has significant but different influences on PBL dynamics and land-atmosphere coupling in the spring and fall in the Great Plains and Eastern United States. In the spring, earlier plant phenology significantly decreases PBL height in the Great Plains by more than 100 m. In the autumn, the Great Plains experience a significant increase in PBL height of over 100 m in the early fall while Eastern US exhibits a significant increase in the late fall when prescribed senescence is shifted earlier. As shifts in plant phenology alone can cause significant changes in PBL conditions at the seasonal timescale in the Great Plains and Eastern US, our experiments can help infer the potential location and magnitude of phenology-induced changes and provide useful information for observation-based analysis and model evaluation.

CARE TO PLAN: TAILORING RESOURCES FOR DEMENTIA CAREGIVERS ACROSS A HEALTH SYSTEM

Abstract Each day, millions of persons with Alzheimer’s disease or related dementias (ADRD) rely on family members for necessary care and support. While there are many well-documented interventions to support ADRD caregivers, they lack individualization for specific caregiver needs and contexts. Care to Plan (CtP) was designed to address this gap in tailoring recommendations to support caregivers. After a Phase I pilot, CtP was refined and implemented within a moderately sized health system in the eastern US. A mixed-methods randomized controlled trial aimed to provide insights into the efficacy, acceptability, and utility of CtP. Twenty-two caregivers were randomly assigned to the treatment group (to review the CtP tool with a senior care navigator) and 21 were assigned to receive usual care. After completion of usual care procedures, 7 participants joined a waitlist control group, following treatment procedures. Three- and six-month outcomes included caregiver self-efficacy and distress, caregiver use of recommended support, and service utilization by the person with memory loss. Most caregivers were white (81%), female (74%), and cared for a parent (56%) or spouse (35%). The majority of caregivers agreed that the tool was helpful (70%) and would recommend it to other caregivers (83%). While 48% of caregivers felt that resources provided by the tool were not new to them, the checklist scores and interviews indicate that the senior care navigators were valuable in discussing the recommendations. Phase II findings will guide future evaluation and dissemination, and inform future models of CtP for health system usage.

Estimating heat tolerance of buds in southeastern US trees in fire-prone forests

BackgroundTraits of mature trees, such as bark thickness and texture, have been documented to promote resistance or resilience to heating in fire-prone forests. These traits often assist managers as they plan and promote prescribed fire management to accomplish specific land management objectives. Species are often grouped together as pyrophobes or pyrophytes as a result of these features. Nonetheless, little is known about species-specific traits of other structures, such as bud diameter, length, mass, moisture content, and surface area, that might be related to heat tolerance. Many prescribed fires are utilized in the eastern United States to control regeneration of less desired species, which could apply a more mechanistic understanding of energy doses that result in topkilling mid-story stems. In this study, we investigated potential relationships between terminal bud mortality from lateral branches of midstory stems and species-specific bud features of six eastern US deciduous trees. Characterized at maturity as either pyrophytes or pyrophobes, each was exposed to different heat dosages in a laboratory setting.ResultsBud diameter, length, mass, moisture content, and surface area differed by species. Bud percent mortality at the first heat flux density (0.255–0.891MJm−2) was highest for two pyrophobes, chestnut oak (Quercus montana Willd.) and scarlet oak (Quercus coccinea Münchh). For the second heat flux density (1.275–1.485MJm−2), bud percent mortality was highest for these species and red maple (Acer rubrum L.). Principal component analysis suggested that bud surface area and length differentiated species. Red maple, chestnut oak, and scarlet oak produced clusters of buds, which may explain their more pronounced bud mortality. Yellow-poplar (Liriodendron tulipifera L.) was also present in that cluster, suggesting that its unique bud architecture of pre-emergent leaves may have elicited responses most similar to those of the clustered buds.ConclusionsContrary to expectations, lateral buds of species regarded as pyrophytes at maturity displayed some of the highest values of bud percent mortality when heated at two heat flux densities generated in a laboratory. Their responses may be related to clustering of their lateral buds. Testing of additional species using these methods in a laboratory setting, and perhaps additional methodologies in the field, is warranted.