Smoky Mountains National Park Research Articles

Natural selection on feralization genes contributed to the invasive spread of wild pigs throughout the United States.

Despite a long presence in the contiguous United States (US), the distribution of invasive wild pigs (Sus scrofa × domesticus) has expanded rapidly since the 1980s, suggesting a more recent evolutionary shift towards greater invasiveness. Contemporary populations of wild pigs represent exoferal hybrid descendants of domestic pigs and European wild boar, with such hybridization expected to enrich genetic diversity and increase the adaptive potential of populations. Our objective was to characterize how genetic enrichment through hybridization increases the invasiveness of populations by identifying signals of selection and the ancestral origins of selected loci. Our study focused on invasive wild pigs within Great Smoky Mountains National Park, which represents a hybrid population descendent from the admixture of established populations of feral pigs and an introduction of European wild boar to North America. Accordingly, we genotyped 881 wild pigs with multiple high-density single-nucleotide polymorphism (SNP) arrays. We found 233 markers under putative selection spread over 79 regions across 16 out of 18 autosomes, which contained genes involved in traits affecting feralization. Among these, genes were found to be related to skull formation and neurogenesis, with two genes, TYRP1 and TYR, also encoding for crucial melanogenesis enzymes. The most common haplotypes associated with regions under selection for the Great Smoky Mountains population were also common among other populations throughout the region, indicating a key role of putatively selective variants in the fitness of invasive populations. Interestingly, many of these haplotypes were absent among European wild boar reference genotypes, indicating feralization through genetic adaptation.

Invasibility of a North American soil ecosystem to amphibian-killing fungal pathogens.

North American salamanders are threatened by intercontinental spread of chytridiomycosis, a deadly disease caused by the fungal pathogen Batrachochytrium salamandrivorans (Bsal). To predict potential dispersal of Bsal spores to salamander habitats, we evaluated the capacity of soil microbial communities to resist invasion. We determined the degree of habitat invasibility using soils from five locations throughout the Great Smoky Mountains National Park, a region with a high abundance of susceptible hosts. Our experimental design consisted of replicate soil microcosms exposed to different propagule pressures of the non-native pathogen, Bsal, and an introduced but endemic pathogen, B. dendrobatidis (Bd). To compare growth and competitive interactions, we used quantitative PCR, live/dead cell viability assays, and full-length 16S rRNA sequencing. We found that soil microcosms with intact bacterial communities inhibited both Bsal and Bd growth, but inhibitory capacity diminished with increased propagule pressure. Bsal showed greater persistence than Bd. Linear discriminant analysis (LDA) identified the family Burkolderiaceae as increasing in relative abundance with the decline of both pathogens. Although our findings provide evidence of environmental filtering in soils, such barriers weakened in response to pathogen type and propagule pressure, showing that habitats vary their invasibility based on properties of their local microbial communities.

Assessment of discontinuity-controlled rock slope instability for debris slide initiation: a GIS-based kinematical analysis in the Great Smoky Mountains National Park, TN, USA

Assessment of discontinuity-controlled rock slope instability for debris slide initiation: a GIS-based kinematical analysis in the Great Smoky Mountains National Park, TN, USA

No long‐term effect of black bear removal on elk calf recruitment in the southern Appalachians

AbstractIn 2001 and 2002, 52 elk (Cervus canadensis; 21 males, 31 females), originally obtained from Elk Island National Park, Alberta, Canada, were transported and released into Cataloochee Valley in the northeastern portion of Great Smoky Mountains National Park (GRSM, Park), North Carolina, USA. The annual population growth rate (λ) was negative (0.996, 95% CI = 0.945–1.047) and predation by black bears (Ursus americanus) on elk calves was identified as an important determinant of population growth. From 2006 to 2008, 49 bears from the primary elk calving area (i.e., Cataloochee Valley) were trapped and translocated about 70 km to the southwestern portion of the Park just prior to elk calving. Per capita recruitment (i.e., the number of calves produced per adult female that survive to 1 year of age) increased from 0.306 prior to bear translocation (2001–2005) to 0.544 during years when bears were translocated (2006–2008) and λ increased to 1.118 (95% CI = 1.096–1.140). Our objective was to determine whether per capita calf recruitment rates after bear removal (2009–2019) at Cataloochee were similar to the higher rates estimated during bear removal (i.e., long‐term response) or if they returned to rates before bear removal (i.e., short‐term response), and how those rates compared with recruitment from portions of our study area where bears were not relocated. We documented 419 potential elk calving events and monitored 129 yearling and adult elk from 2001 to 2019. Known‐fate models based on radio‐telemetry and observational data supported calf recruitment returning to pre‐2006 levels at Cataloochee (short‐term response); recruitment of Cataloochee elk before and after bear relocation was lower (0.184) than during bear relocation (0.492). Recruitment rates of elk outside the removal area during the bear relocation period (0.478) were similar to before and after rates (0.420). In the Cataloochee Valley, cause‐specific annual calf mortality rates due to predation by bears were 0.319 before, 0.120 during, and 0.306 after bear relocation. In contrast, the cause‐specific annual mortality rate of calves in areas where bears were not relocated was 0.033 after the bear relocation period, with no bear predation on calves before or during bear relocation. The mean annual population growth rate for all monitored elk was 1.062 (95% CI = 0.979–1.140) after bear relocation based on the recruitment and survival data. Even though the effects of bear removal were temporary, the relocations were effective in achieving a short‐term increase in elk recruitment, which was important for the reintroduction program given that the elk population was small and vulnerable to extirpation.

Past and Ongoing Field-Based Studies of Myxomycetes.

Evidence from molecular studies indicates that myxomycetes (also called myxogastrids or plasmodial slime molds) have a long evolutionary history, and the oldest known fossil is from the mid-Cretaceous. However, they were not "discovered" until 1654, when a brief description and a woodcut depicting what is almost certainly the common species Lycogala epidendrum was published. First thought to be fungi, myxomycetes were not universally recognized as completely distinct until well into the twentieth century. Biodiversity surveys for the group being carried out over several years are relatively recent, with what is apparently the first example being carried out in the 1930s. Beginning in the 1980s, a series of such surveys yielded large bodies of data on the occurrence and distribution of myxomycetes in terrestrial ecosystems. The most notable of these were the All Taxa Biodiversity Inventory (ATBI) project carried out in the Great Smoky Mountains National Park, the Planetary Biodiversity Inventory Project (PBI) carried out in localities throughout the world, and the Myxotropic project being carried out throughout the Neotropics. The datasets available from both past and ongoing surveys now allow global and biogeographical patterns of myxomycetes to be assessed for the first time.

Optimizing Select Fraser Fir (Abies fraseri) Reforestation Methods within an Artificial Bald at Mount Buckley, Great Smoky Mountains National Park

Optimizing Select Fraser Fir (Abies fraseri) Reforestation Methods within an Artificial Bald at Mount Buckley, Great Smoky Mountains National Park

Comparing passive and active macroinvertebrate sampling gear efficacy during biomonitoring in Southern Appalachian mountain streams

AbstractAquatic invertebrates are important components of any aquatic ecosystem and are frequently monitored to determine the ecological integrity of those systems. Various gear types are used to collect aquatic macroinvertebrates in wadeable streams. We analyzed commonly used active and passive gear types, including kick seines, Hess samplers, drift nets, and Hester–Dendy samplers, across a watershed in the Great Smoky Mountains National Park to determine their efficacy under various habitat conditions in wadeable Southern Appalachian mountain streams. Hester–Dendy samplers were significantly different from other gear types for most univariate and multivariate analyses. Kick and Hess samples were most similar in multivariate comparisons of macroinvertebrate assemblages. Drift samples were similar in most univariate analyses but were distinct from other gear types when analyzed with multivariate techniques. Our results indicate that comprehensive assessments of macroinvertebrate assemblages require multiple gear types, various analytical approaches, and consistent taxonomic resolution. The complexity of the fluvial system in question should be thoroughly assessed prior to formulating a macroinvertebrate biomonitoring protocol to better ensure robust and meaningful results.

An osteometric analysis of elk (Cervus elaphus manitobensis) from Great Smoky Mountains National Park

AbstractTeeth are commonly preserved in the zooarchaeological record and can be used to estimate the age of individuals in a faunal assemblage. However, there are currently no criteria for discerning the sex of elk based on dental metric characteristics. Here, we present the results of an osteometric analysis of modern elk (Cervus elaphus manitobensis) from Great Smoky Mountains National Park to create an age profile for the sample, establish metrical parameters for evaluating sex, and discern the relationship between age and size. The analysis of tooth development stages in younger elk was combined with the assessment of occlusal wear in older elk to create an age profile of our sample population. The length and breadth of mandibular third molars produced bimodal distributions that suggest these measurements can be used to differentiate sex in this population, and diastema length showed a curvilinear association with age (R2 = 0.71). This dataset provides a useful comparative sample for future studies on ageing and sexing in zooarchaeology, conservation paleobiology, and wildlife resources management.

Topographic Drivers of Soil Moisture Across a Large Sensor Network in the Southern Appalachian Mountains (USA)

AbstractUnderstanding the distribution of soil moisture is notoriously difficult in topographically complex regions that are subject to both large‐scale climate gradients and fine‐scale effects of terrain, vegetation, and soil structure. Remote sensing approaches capture large‐scale moisture patterns but are limited in spatial and temporal resolution, while commercial field sensors remain too expensive to deploy intensively over large spatial extents. Here, we demonstrate the use of low‐cost (<20 USD) custom sensors to create a large monitoring network of surficial (0–15 cm depth) volumetric soil moisture content (VMC) across Great Smoky Mountains National Park (GSMNP) (NC, TN, USA). In laboratory tests, temperature‐calibrated VMC values approached the accuracy of commercial probes. We deployed over 80 sensors across multiple watersheds, topographic positions, and a 1,800‐m elevation gradient, and created hierarchical models to understand associations of VMC with spatial (30‐m resolution) and temporal (daily) variables related to water supply and demand. Elevation had the strongest association with VMC, with a fivefold increase across the gradient reflecting 1.5‐fold changes in both (increased) precipitation and (decreased) evapotranspiration; slope angle was a strong mediating factor. Common proxies for moisture including topographic convergence index were not associated with VMC, likely due to limited contributions of surface drainage to local water balance. Our model predicted daily VMC of a set of validation sensors with a root mean square error of 4.8%, which may be improved by site‐specific field calibration. Our study indicates that spatially extensive, field‐based soil moisture networks are practical, accurate, and an important component of regional environmental monitoring.

Parasite Prevalence in Feral Swine (Sus scrofa) from the Great Smoky Mountains National Park, USA.

Feral swine (Sus scrofa) are an introduced species to the Great Smoky Mountains National Park (GSMNP), US, and serve as carriers of several diseases that are considered a threat to other wildlife, domestic animals, and humans. During 2013 and 2015, fecal samples from 67 feral swine from the GSMNP within both Tennessee and North Carolina, US, were opportunistically collected as part of a feral swine removal program and submitted to the University of Tennessee College of Veterinary Medicine, Knoxville, Tennessee, for parasite screening by centrifugal sugar flotation. Ten taxa from the phyla Acanthocephala, Apicomplexa, and Nematoda were identified: Ascaris spp., Strongylid-type spp., Capillaria spp., Trichuris suis, Metastrongylus spp., Macracanthorhynchus spp., Coccidia, Sarcocystis spp., and Cryptosporidium spp. In 98.5% of samples, at least one parasite was found. No differences in parasite prevalence or species diversity were noted based on state of collection (Tennessee or North Carolina), sex, or age. The high prevalence of gastrointestinal parasites in these feral swine, some of which are zoonotic, represents a potential public health risk as well as a concern for free-range swine farmers.

Front Cover

Next article FreeFront CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreOn the cover: Pictured is Sams Creek, a collection site for multiple species of Polycentropus (Trichoptera: Polycentropodidae). The stream is located in Blount County, TN, within Great Smoky Mountains National Park, USA. Photo: Alexander B. Orfinger. Next article DetailsFiguresReferencesCited by Freshwater Science Volume 42, Number 2June 2023 Published on behalf of the Society for Freshwater Science Article DOIhttps://doi.org/10.1086/726106 © 2023 The Society for Freshwater Science.PDF download Crossref reports no articles citing this article.

Fog interception in spruce-fir and mixed northern hardwood forests of Great Smoky Mountains National Park, Southeast USA

Abstract: Fog interception is a significant component of the water balance of Southern Appalachian spruce-fir forests in the Southeast USA. Here, fog interception rates are quantified for spruce-fir and northern hardwood trees in Great Smoky Mountains National Park (GSMNP), Tennessee and North Carolina, as a precursor to examining how interspecific differences in fog interception could affect catchment water balances if there is widespread vegetation change from spruce-fir to hardwoods. A water-balance approach was implemented, based on paired open-site (rainfall) and beneath-canopy (throughfall) electronically recording tipping-bucket rain gauges that were in place in the spruce-fir zone of GSMNP from May to November 2021. Comparing identified fog interception events to actual conditions captured by a webcam, 90% of verifiable events had conditions that were either clearly or potentially favorable for fog interception. Estimated fog interception gain ranged from averages of 0.24 to 0.69 mm day−1, representing 3 to 8% of rainfall. Results are consistent with the expectation of higher fog interception gain for spruce and fir than for birch, the representative hardwood species. Quantification of fog interception rates provides valuable information about ecohydrological processes in ecologically significant Southern Appalachian spruce-fir forests.

A multi-level modeling approach to guide management of female feral hogs in Great Smoky Mountains National Park

AbstractWe trapped, anesthetized, and fit 16 female feral swine (Sus scrofa) with Global Positioning System (GPS) collars in Great Smoky Mountains National Park (GRSM) to develop predictive summer and winter models for more effective population control efforts. Given the highly diverse habitat and topography in GRSM and the spatial extent of our dataset, we employed Step Selection Function (SSF) to evaluate resource selection at the 3rd-order level and Resource Selection Function (RSF) models at the 2nd-order level for both summer and winter seasons. The summer SSF and RSF models suggested relatively similar levels of selection, whereas the winter models differed by method. We created a straightforward consensus model to better visualize the agreement and constraints of each set of models. In summer, feral swine used lower slopes regardless of elevation, especially those closer to human-dominated spaces such as along paved and gravel roadways. In winter, feral swine maintained preference for lower slopes but preferred oak-dominated forest areas and selection for human development was less than in summer. Wildlife managers can use these models to better focus feral swine surveillance and management in GRSM. Managers can identify areas of high use by season and plan control activities that are both accessible and highly efficient. The combination and consensus framework presented here can be applied to other systems where species’ habitat selection may result in incongruous results across different levels of selection or seasons of interest.

Assessing impacts of sulfur deposition on aquatic ecosystems: A decision support system for the Southern Appalachians

AbstractWith climate change and ongoing impacts from human development and resource extraction, US federal land management agencies are acutely concerned with managing for healthy aquatic ecosystems in the Southern Appalachian Mountain (SAM) Region. Here, we describe development of a spatial decision support application to assess the biological and ecological impacts of atmospheric S and N deposition on aquatic ecosystems of the region. We first summarize foundational published work to predict continuous maps of surface water acid neutralizing capacity (ANC) and soil base cation weathering (BCw). We use the predicted ANC and BCw maps to estimate steady‐state critical loads (CLs) of atmospheric S and N deposition. We included estimated CLs of atmospheric N to get a complete picture of CLs and potential exceedances. We then present a logic‐based decision support model for assessing effects of S and N deposition based on statistically modeled stream ANC and CL exceedance. The model is easily modified for continuous monitoring of CL exceedance patterns as new S and N deposition and ANC data become available. We present mapped model results for the SAM study area and an important subset of the region, the Great Smoky Mountains National Park. ANC modeling results revealed that predicted acid sensitivity was spatially variable, with areas of relatively low stream ANC (<50 μeq · L−1) and soil BCw (<50 meq · m−2 · year−1) predominantly found in certain critical areas. Within the Great Smoky Mountains National Park, evidence for S CL exceedance based on an ANC criterion of 50 μeq · L−1 was strong at locations where ambient S deposition was at least two times the CL. We also predicted likely impacts of CL exceedances on aquatic insect species richness and native fish abundance. Responses for insect species richness and fish impact showed variability similar to CL exceedance, with increasing impact positively correlated with elevation. Finally, we discuss ways that the decision support system can be used to prioritize management across the region.

Contrasting effects of urbanization and fire on understory plant communities in the natural and wildland–urban interface

AbstractAs human populations expand and land‐use change intensifies, terrestrial ecosystems experience concurrent disturbances (e.g., urbanization and fire) that may interact and compound their effects on biodiversity. In the urbanizing landscapes of the southern Appalachian region of the United States of America (US), fires in mesic forests have become more frequent in recent years. However, 80 years of forest management practices aimed at fire suppression in this region may have decreased landscape resistance or resilience to high‐severity fires. At the same time, housing development is rapidly expanding in the wildland–urban interface, creating opportunities to examine the combined effects of urbanization and fire disturbances on plant communities when fires occur. Here, we investigated how understory plant communities were affected by a fire that varied in severity at sites in Gatlinburg, TN, and in the adjacent Great Smoky Mountains National Park. Our goal was to investigate the individual and combined effects of fire and urbanization on plant community composition in the second growing season after a fire. Overall, we found a significant interaction effect of fire severity and urbanization on total plant abundance and richness, such that increasing fire severity was associated with lower abundance and richness in natural areas but higher abundance and richness in exurban areas. Shannon diversity was significantly affected by fire severity and urbanization, but not interactively. Plant composition was affected by fire severity, urbanization, and their interaction effects. Understory plant communities in exurban locations (low‐density residential areas near protected lands) were resilient following the pulse disturbance event (fire), likely because of their consistent exposure to a press disturbance (urbanization). Our study indicates a press disturbance may change the way a subsequent pulse disturbance affects plant communities. Our findings contribute new insights into how disturbances can interact to alter patterns of biodiversity in the southeastern US.

Wildfire severity alters soil microbial exoenzyme production and fungal abundances in the Southern Appalachian Mountains

Climate change has increased drought frequency and duration that are exacerbated by increased temperatures globally. This effect has, and will continue, to increase fire occurrence across many regions of North America. In the Southern Appalachian Mountains, wildfires with high severity occurred in 2016 due to increased drought and human activity. Surface soils were collected from two sites: the Great Smoky Mountains National Park (GRSM) in Tennessee and the Nantahala National Forest (NNF) in North Carolina, USA spanning light, moderate, and severely burned areas, accompanied by adjacent unburned locations that act as controls. Surface soil samples to a depth of 15 cm were collected at three time points between 2017 and 2019 (~0.5 years, ~1 year, and 2.5 years post-fire) among burn severity plots. Total hydrolytic enzyme production varied over time with severe plots having significantly lower enzyme production at 2.5 years post wildfire. Individual enzymes varied among burn severity treatments and time. Light burns elicited greater carbon-specific (β-glucosidase (BG), β-xylosidase (BX)) and P-specific (acid phosphatase) activities six months post-fire, but this effect was transient. After 2.5 years post-burn, BX and AP were lower in severe or moderate burns relative to controls. In contrast, leucyl aminopeptidase (LAP) was lowest in severe burns six months post-fire, but by 2.5 years, was lowest in light burns. Fungal:bacterial ratios declined with burn severity indicative that fungi are sensitive or less resilient to high fire severity during recovery. These results suggest wildfires alter trajectories for soil microbial structure and function within a 2.5-year timeframe which potentially has long-term impacts on biogeochemical cycling.

A NEW SPECIES OF FLEA (SIPHONAPTERA: CTENOPHTHALMIDAE) PARASITIZING VOLES AT HIGH ELEVATIONS IN THE GREAT SMOKY MOUNTAINS OF TENNESSEE AND NORTH CAROLINA.

Both sexes of Catallagia appalachiensis n. sp. are described from high elevation spruce-fir forests in Sevier County, Tennessee and adjoining Swain County, North Carolina in the Great Smoky Mountains National Park. The type host of the new flea is the southern red-backed vole, Myodes gapperi (Vigors) (25 flea specimens), although small numbers of specimens were also collected from a sympatric northern short-tailed shrew, Blarina brevicauda (Say) (2 fleas), a red squirrel, Tamiasciurus hudsonicus (Erxleben) (1 flea), and a North American deer mouse, Peromyscus maniculatus (Wagner) (1 flea). Infestation prevalences for these hosts are provided. The new species is compared morphologically with other known species of Catallagia, in particular with Catallagia borealis, the only other described congeneric flea in eastern North America. This is the first new species of flea to be described from the eastern United States since 1980.

Characterizing spatial burn severity patterns of 2016 Chimney Tops 2 fire using multi-temporal Landsat and NEON LiDAR data

The Chimney Tops 2 wildfire (CT2) in 2016 at Great Smoky Mountains National Park (GSMNP) was recorded as the largest fire in GSMNP history. Understanding spatial patterns of burn severity and its underlying controlling factors is essential for managing the forests affected and reducing future fire risks; however, this has not been well understood. Here, we formulated two research questions: 1) What were the most important factors characterizing the patterns of burn severity in the CT2 fire? 2) Were burn severity measures from passive and active optical remote sensing sensors providing consistent views of fire damage? To address these questions, we used multitemporal Landsat- and lidar-based burn severity measures, i.e., relativized differenced Normalized Burn Ratio (RdNBR) and relativized differenced Mean Tree Height (RdMTH). A random forest approach was used to identify key drivers in characterizing spatial variability of burn severity, and the partial dependence of each explanatory variable was further evaluated. We found that pre-fire vegetation structure and topography both play significant roles in characterizing heterogeneous mixed burn severity patterns in the CT2 fire. Mean tree height, elevation, and topographic position emerged as key factors in explaining burn severity variation. We observed generally consistent spatial patterns from Landsat- and lidar-based burn severity measures. However, vegetation type and structure-dependent relations between RdNBR and RdMTH caused locally inconsistent burn severity patterns, particularly in high RdNBR regions. Our study highlights the important roles of pre-fire vegetation structure and topography in understanding burn severity patterns and urges to integrate both spectral and structural changes to fully map and understand fire impacts on forest ecosystems.

Using an Inventory of Unstable Slopes to Prioritize Probabilistic Rockfall Modeling and Acid-Base Accounting in Great Smoky Mountains National Park

Abstract An important first step in the geotechnical asset management of Great Smoky Mountains National Park (GRSM) is the creation of an unstable slope inventory along major transportation corridors. Slope-stability problems are frequent in GRSM, often initiated in highly weathered and fractured metasedimentary rocks. In this study, an unstable slope inventory was created using the Unstable Slope Management Program for Federal Land Management Agencies protocols. Hazards and risks were evaluated for 285 unstable slopes along 243.67 km of roadway. Kernel density estimation was used to identify unstable slope hotspots and establish 14 sites for site-specific investigations to evaluate potential impacts of discrete unstable slopes along major roadways. Two-dimensional probabilistic rockfall simulations and acid-base accounting tests were used to predict rockfall pathways and evaluate the acid-producing potential of rocks. Simulations indicated that rock material would likely enter the roadway at all 14 sites. Acid-base accounting test results indicated that slaty rocks of the Anakeesta Formation and graphitic schist of the Wehutty Formation are primary acid-producing rocks in rockfall-prone areas. This research illustrates an approach for prioritizing areas for site-specific investigations towards the goal of improving safety in GRSM, including developing mitigation strategies for rockfall by widening ditches, installing barriers, and encapsulating acidic rockfall material.

Great Smoky Mountains National Park and its Missing Black Visitors: A Preliminary Analysis on the Hidden Architecture of Landscape

The framing of national parks as "America's best idea" has undergone a multi-disciplinary critique for its failure to address the scarcity of racial minority visitors, particularly Black Americans. Slavery, segregation, and ongoing racial politics demand a process of unlearning and undoing by centering Black voices. This research seeks to re-examine Black Americans' motivations for and deterrents against visiting national parks using Great Smoky Mountains National Park (GSMNP) as a preliminary case study. A review of archival documents (e.g., park history and promotional materials), interpretation programs, exhibits, and the racial composition of surrounding communities and park employees was conducted to identify gaps in Black Americans' representation within the core messages created and promoted by GSMNP. The results suggest that Black Americans are rarely seen in archival documents, and marginally represented in publicly accessible literature and exhibits. This legacy may send a message to Black Americans that the park is a "White" space, where their ancestors were treated as second-class citizens or excluded entirely. Under the shadow of Jim Crow laws, segregation, racism, and discrimination, this space may have been associated with danger or considered unsafe and unwelcoming. Our findings contribute to the broader understanding of how landscapes and institutions are racialized, and how the power of narrative can be used to dismantle racialization.