Fire-maintained ecosystems and associated species are becoming increasingly rare in the southern Appalachian Mountains because of fire suppression policies implemented in the early 20th century. ...Restoration of these communities through prescribed fire has been hindered by a lack of information on historical fire regimes. To characterize past fire regimes, we collected and absolutely dated the tree rings on cross sections from 242 fire-scarred trees at three different sites in the southern Appalachian Mountains of Tennessee and North Carolina. Our objectives were to (1) characterize the historical frequency of fire in southern Appalachian mixed pine-oak forests, (2) assess the impact of interannual climatic variability on the historical occurrence of fire, and (3) determine whether changes in human culture and land use altered the frequency of fire. Results demonstrate that fires burned frequently at all three sites for at least two centuries prior to the implementation of fire suppression and prevention in the early to mid 20th century. Composite mean fire return intervals were 2-4 yr, and point mean fire return intervals were 9-13 yr. Area-wide fires that burned across multiple stands occurred at 6-13-yr intervals. The majority of fires were recorded during the dormant season. Fire occurrence exhibited little relationship with reconstructed annual drought conditions. Also, fire activity did not change markedly during the transition from Native American to Euro-American settlement or during the period of industrial logging at the start of the 20th century. Fire activity declined significantly, however, during the fire suppression period, with a nearly complete absence of fire during recent decades. The characterization of past fire regimes should provide managers with specific targets for restoration of fire-associated communities in the southern Appalachian Mountains. The fire chronologies reported here are among the longest tree-ring reconstructions of fire history compiled for the eastern United States and support the hypothesis that frequent burning has played a long and important role in the development of forests in the southern Appalachian Mountains.
•We characterize past tree establishment under frequent fire and fire exclusion.•Distinct post-fire cohorts are evident along the entire south slope.•Tree establishment shifted toward mesophytic, ...fire intolerant species.•Community differentiation declined along the topographic moisture gradient.
Patterns of past fire disturbance may be an important contributor to contemporary vegetation composition and structure in old-growth forests of the southern Appalachian Mountains. However, due to a lack of information on pre-suppression fire regimes, vegetation pattern in the region has been primarily attributed to variability in soils and climate. To assess the pre-suppression fire regime’s role in shaping vegetation pattern, we characterized temporal patterns of tree establishment in an old-growth forest that experienced two centuries of frequent fire, followed by a century of fire exclusion. Forest plots were inventoried and cored to characterize age structure and composition in yellow pine, chestnut oak, white pine-oak, and cove forest communities on the south-facing slope of an old-growth watershed in Great Smoky Mountains National Park, Tennessee USA. We compared the timing and composition of tree establishment from the following disturbance periods: (1) frequent fire 1700–1909; (2) post fire 1910–1949; and (3) mesophication 1950–2000. Non-metric multidimensional scaling characterized successional change between the three age classes. Multivariate dispersion, species richness, and beta diversity were calculated for establishment in each disturbance period. We found distinct peaks in tree establishment in the yellow pine, chestnut oak, and white pine-oak stand types that occurred soon (<40years) after fire cessation at the site. Xerophytic fire-tolerant species dominated establishment during the period of frequent fire; a mixture of xerophytic and mesophytic species established during the period immediately following the last major fire; and mesophytic, fire-intolerant species dominated establishment during the recent period of mesophication. Cohort recruitment was less clearly linked to fire suppression in the mesic cove stands; however “fire protected” cove stands exhibited different age structure and composition compared to cove stands adjacent to the frequently burned south-facing slope. Mean plot level species richness was greatest in the tree cohort that established soon after the last major fire; while beta diversity and multivariate dispersion were highest in the trees that had established during the frequent fire period. Tree establishment has generally shifted from shade-intolerant, drought-tolerant species to shade-tolerant, drought-intolerant species along the entire south-facing slope. Successional trajectory indicates a loss of yellow pine and chestnut oak communities as the xeric and sub-xeric sites convert to white pine and cove forest communities, which were formerly restricted to sub-mesic and mesic positions. Declines in beta diversity and multivariate dispersion within younger age classes indicate that in the absence of fire disturbance, community differentiation is declining along the topographic moisture gradient.
Background Shared medical appointments (SMAs) in heart failure (HF) are medical visits where several patients with HF meet with multidisciplinary providers at the same time for efficient and ...comprehensive care. It is unknown whether HF‐SMAs can improve overall and cardiac health status for high‐risk patients with HF discharged from acute care. Methods and Results A 3‐site, open‐label, randomized‐controlled‐trial was conducted. Participants within 12 weeks of HF acute care (emergency‐room/hospitalization) requiring intravenous diuretic therapy were randomized to receive either HF‐SMA or usual HF clinical care (usual‐care) on a 1:1 ratio. The HF‐SMA team, which consisted of a nurse, nutritionist, psychologist, nurse practitioner and/or a clinical pharmacist, provided four 2‐hour session HF‐SMAs that met every other week for 8 weeks. Primary outcomes were the overall health status measured by European Quality of Life Visual Analog Scale and cardiac health status by Kansas City Cardiomyopathy Questionnaire, 180 days postrandomization. Of the 242 patients enrolled (HF‐SMA n=117, usual‐care n=125, mean age 69.3±9.4 years, 71.5% White patients, 94.6% male), 84% of participants completed the study (n=8 HF‐SMA and n=9 usual‐care patients died). After 180 days, both HF‐SMA and usual‐care participants had significant improvements from baseline in Kansas City Cardiomyopathy Questionnaire that were not statistically different. Only HF‐SMA participants had significant improvements in European Quality of Life Visual Analog Scale (mean change = 7.2±15.8 in HF‐SMA versus −0.4±19.0 points in usual‐care, P < 0.001). Conclusions Both HF‐SMA and usual‐care in participants with HF achieved significant improvements in cardiac health status, but only a team approach through HF‐SMA achieved significant improvements in overall health status. Future larger studies are needed to evaluate hospitalization and death outcomes. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02481921.
The Rocky Mount Historic Site (40SL386) in Piney Flats, Tennessee, houses structures that many believe date to the founding of the Tennessee territory, ca. 1770, when settlers from North Carolina and ...elsewhere traversed the southern Appalachian Mountains to establish new homes along the western frontier. Rocky Mount was purportedly built by William Cobb between 1770 and 1772. We cored logs on the Cobb House and adjacent Dining Room to date the tree rings and determine when these trees were harvested. Our analyses yielded 88 measurement series from 69 logs (45 from the Cobb House and 24 from the Dining Room), 39 of which yielded cutting dates. The Cobb House contained logs cut as early as spring 1826 and as late as 1828, while the Dining Room contained logs cut between 1828 and 1830. We conclude that the Cobb House and adjacent Dining Room were not built by William Cobb between 1770 and 1772 but were instead built between 1826 and 1830 by Michael Massengill, a grandson of William Cobb. Archaeological and architectural analyses performed previously provide corroborating evidence of these later construction dates. Documentary evidence supports the location of land owned by William Cobb south of the Watauga River between Carroll Creek and Knob Creek, just to the west of present-day Johnson City.
An estimated 3.5 billion people are colonized by intestinal parasites worldwide. Intestinal parasitic eukaryotes interact not only with the host but also with the intestinal microbiota. In this work, ...we studied the relationship between the presence of multiple enteric parasites and the community structures of gut bacteria and eukaryotes in an asymptomatic mother-child cohort from a semirural community in Mexico. Fecal samples were collected from 46 mothers and their respective children, with ages ranging from 2 to 20 months. Mothers and infants were found to be multiparasitized by Blastocystis hominis, Entamoeba dispar, Endolimax nana, Chilomastix mesnili, Iodamoeba butshlii, Entamoeba coli, Hymenolepis nana, and Ascaris lumbricoides. Sequencing of bacterial 16S rRNA and eukaryotic 18S rRNA genes showed a significant effect of parasite exposure on bacterial beta-diversity, which explained between 5.2% and 15.0% of the variation of the bacterial community structure in the cohort. Additionally, exposure to parasites was associated with significant changes in the relative abundances of multiple bacterial taxa, characterized by an increase in
and decreases in
and
. Parasite exposure was not associated with changes in intestinal eukaryote relative abundances. However, we found several significant positive correlations between intestinal bacteria and eukaryotes, including
with
and Prevotella stercorea with Entamoeba hartmanni, as well as the co-occurrence of the fungus
with
and
,
, and Prevotella copri and the fungus
with
. The parasitic exposure-associated changes in the bacterial community structure suggest effects on microbial metabolic routes, host nutrient uptake abilities, and intestinal immunity regulation in host-parasite interactions.
The impact of intestinal eukaryotes on the prokaryotic microbiome composition of asymptomatic carriers has not been extensively explored, especially in infants and mothers with multiple parasitic infections. In this work, we studied the relationship between protist and helminth parasite colonization and the intestinal microbiota structure in an asymptomatic population of mother-child binomials from a semirural community in Mexico. We found that the presence of parasitic eukaryotes correlated with changes in the bacterial gut community structure in the intestinal microbiota in an age-dependent way. Parasitic infection was associated with an increase in the relative abundance of the class
and decreases of
and
. Parasitic infection was not associated with changes in the eukaryote community structure. However, we observed strong positive correlations between bacterial and other eukaryote taxa, identifying novel relationships between prokaryotes and fungi reflecting interkingdom interactions within the human intestine.
The Lund-Spathelf House is located at 1526 Pontiac Trail in Ann Arbor, Michigan. During a
recent renovation, the owner sought information regarding the construction of the house by searching through ...numerous written records. Despite an extensive history of the land on which the house currently sits, neither a construction year nor general period of construction could be obtained. Therefore, four samples of oak (Quercus spp.) were extracted from floor boards throughout the house for dendrochronological dating. The four samples crossdated conclusively with each other both visually and statistically and were used to build a floating 126-year tree-ring chronology. We used COFECHA to statistically evaluate the absolute temporal placement of this chronology against a nearby regional chronology (MI005.CRN) from the Cranbrook Institute, Michigan. The Lund-Spathelf House chronology was anchored in time with the regional chronology from A.D. 1720 to 1845 with a correlation coefficient of 0.62 (p < 0.0001, t < 8.76, n = 126). All four oak samples provided conclusive cutting dates of A.D. 1845, indicating the year the Lund-Spathelf House was constructed.
We investigated the climatic sensitivity of oak species across a wide elevation range in the
southern Appalachian Mountains, an area where greater knowledge of oak sensitivity is desired. We ...developed three tree-ring chronologies for climatic analyses from oak cores taken from the Jefferson National Forest, Virginia, and Great Smoky Mountains National Park, Tennessee. We statistically compared the three chronologies with monthly climatic data from 1930 to 2005. The results of our analyses suggest that oak species in the southern Appalachian Mountains require a cool, moist summer for above average-growth to occur. The climate signal increased in duration from high to low elevational and latitudinal gradients, indicating a strong moisture-preconditioning signal during the previous fall at our lowest elevation site. A notable finding of this research was the degree of responsiveness in oaks that are growing in forest interior locations where strong climate sensitivity would not be expected because of the effects of internal stand dynamics. Furthermore, the relationships between evapotranspiration rates and the geographic factors of elevation, latitude, and aspect influence the climate signals at the three sites. Our research suggests that oaks located in a warm and xeric climate experience more physiological stress and put forth a more varied climatic response.
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