A comparison of streams in logged and unlogged areas of Great Smoky Mountains National Park

Second order streams draining areas of virgin forest in Great Smoky Mountains National Park, Tennessee and North Carolina, U.S.A., are compared to those which drain forests logged before the establishment of the park in the 1930's. Water quality of two main study streams (one unlogged and one formerly logged) was compared and the unlogged stream had generally higher levels of dissolved solids and lower levels of suspended particulates than the logged stream. Stream channel characteristics were compared on four logged and four unlogged streams. The unlogged streams had over four times more (by volume) of woody debris and 10 times more material in debris dams than the logged streams. Only minor differences in substrate composition were observed. Macroinvertebrate samples from the four logged and four unlogged streams showed that the logged streams contained greater numbers of organisms and more taxa. More detailed sampling on the two main study streams showed similar patterns of more individuals and more taxa in the logged stream, as well as differences in the composition of five functional groups. These differences in invertebrate fauna may be due to differences in quantity and quality of leaf litter inputs, although other explanations are also possible.     

Trichomycete insect symbionts in Great Smoky Mountains National Park and vicinity

Collections of trichomycete symbionts of larval aquatic insects in Great Smoky Mountains National Park and vicinity in the southern Appalachian region of the USA resulted in finding many taxa of Harpellales, including an unusual new monotypic genus, Barbatospora ambicaudata in Simuliidae, and five new species in Thaumaleidae or Chironomidae, Harpellomyces montanus, Smittium lentaquaticum, Sm. minutisporum, Stachylina gravicaudata and St. stenospora. In addition a new species of Amoebidium (Amoebidiales), A. appalachense, attached to the anal tubules of bloodworms (Chironomidae) is described. Axenic cultures of three of the new taxa were obtained, plus Sm. culisetae. Fourteen identified species representing 13 genera of previously known Harpellales are recorded from Plecoptera, Ephemeroptera and Diptera, as well as a new Dipteran host record for an unidentified harpellid that was found in a Blephariceridae. Also identified were Paramoebidium corpulentum and many undetermined species of Paramoebidium (Amoebidiales) from four orders of aquatic insect larvae. The occurrence of an Enterobryus species in Diplopoda and another Eccrinales from an aquatic beetle is noted. Amoebidiales,     

Genetic diversity of flowering dogwood in the Great Smoky Mountains National Park

In the past three decades, flowering dogwood (Cornus florida) populations have experienced severe declines caused by dogwood anthracnose. Mortality has ranged from 48% to 98%, raising the concern that the genetic diversity of this native tree has been reduced significantly. In this study, we investigated levels of genetic diversity and population structure of flowering dogwood populations in the Great Smoky Mountains National Park (GSMNP). Understanding the factors influencing geographic distribution of genetic variation is one of the major concerns for preserving biodiversity and conservation of native populations. Eighteen microsatellite loci were used to evaluate the level and distribution of genetic variation of native flowering dogwood trees throughout the GSMNP. Significant genetic structure exists at both landscape and local levels. Two genetic clusters exist within the park and are separated by the main dividing ridges of the Great Smoky Mountains. The differentiation of the clusters is subtle, but statistically significant. Gene flow, evident through low-elevation corridors, indicates that nonrandom mating occurs between related individuals despite wide dispersal of seeds. Although high mortality rate and reduced fecundity caused by dogwood anthracnose severely affected native flowering dogwood populations throughout the entire GSMNP, this study confirmed that considerable genetic diversity still exists at the population level. It seems unlikely that recent demographic dynamics have resulted in a depletion of genetic variation.     

Primary productivity and spatial structure of phytolithic growth in streams in the Great Smoky Mountains National Park,Tennessee

The purpose of this study was to examine the primary production rates of phytolithic communities found in the major different habitats of streams and determine the effects of physical and chemical parameters associated with each habitat on periphyton community spatial structure. The project was designed to study natural, intact communities within stream systems.A comparative analysis was made of phytolithic communities found in Camel Hump and Husky Branch streams in the Great Smoky Mountains National Park. Camel Hump flows through virgin forest area and Husky Branch flows through an area logged approximately 60 y ago. The effects of logging on Husky Branch stream and the surrounding watershed are discussed.Seasonal data were collected from July, 1981 through May, 1982 from fast flow, slow flow and pool areas within each stream. An incubation chamber designed for use in lotic systems was used for in situ measurements of ¹⁴C uptake. Rock samples collected at each site were used as substrates for community structure observations utilizing a scanning electron microscope.The algal communities of Camel Hump and Husky Branch streams were found to be predominantly composed of diatoms. The dominant genera in the fast, slow and pool areas included Achnanthes, Eunotia, Meridion, Navicula and Gomphonema. Fast flow areas were dominated by diatom species growing in a prostrate position. Slow flow areas were more densely populated by diatoms than the fast flow areas. Diatoms in the slow flow areas appeared mainly in prostrate position with a few stalked forms present. Pool area communities were less densely packed than slow flow areas and contained stalked and chain formations of diatoms.Results indicate that the physical and chemical parameters associated with each habitat affect the primary production rates and community structure found at the experimental sites. Measurements of carbon assimilation and chlorophyll a concentration were significantly greater in habitats of higher current velocity and light availability. Cell densities tend to increase with a decrease in current velocity. Habitats of high density showed a decrease in diversity and evenness. Correlations between productivity in the various habitats of each stream and other parameters measured in the study are discussed.     

New species of small dictyostelids from the Great Smoky Mountains National Park

Ten new species of small dictyostelids, five belonging to Acytostelium (A. anastomosans, A. longisorophorum, A. magnisorum, A. serpentarium and A. singulare) and five to Dictyostelium (D. amphisporum, D. naviculare, D. oculare, D. potamoides and D. stellatum), were isolated from forest soils in the Great Smoky Mountains National Park. These species were recovered mostly from acidic soils and at higher elevations. They represent a large group of dictyostelids of small stature (<2 mm total height) on which we are beginning to accumulate more information.     

Distribution and ecology of dictyostelid cellular slime molds in Great Smoky Mountains National Park

Great Smoky Mountains National Park encompasses an area of 2080 km2 in eastern Tennessee and western North Carolina between 35 degrees 28' and 35 degrees 47' N. Elevations are 270-2000 m above sea level, and the topography and vegetation are as diverse as any region of eastern North America. In 1998-2004 soil/litter samples for isolation of dictyostelid cellular slime molds were collected throughout the park. Collecting sites included examples of all major forest types along with the more common types of nonforest vegetation. More than 2300 clones of dictyostelids were recovered from 412 samples. These clones included representatives of 20 described species together with at least 10 species new to science. This total is higher than those reported for other temperate regions of the world. In general both numbers of species and numbers of clones/g of sample material decreased with increasing elevation and several species displayed a distinct preference for either the low or high end of the elevation gradient. The relatively high number of new species recovered from samples collected at high elevations is an important new finding for dictyostelid ecology and distribution.     

Vertical distribution and assemblages of corticolous myxomycetes on five tree species in the Great Smoky Mountains National Park

Corticolous myxomycetes of the Great Smoky Mountains National Park were studied in relation to their association with certain tree species and height of occurrence in the forest canopy. Using the double-rope climbing method, bark was collected at 3 m increments to the tops of trees of five different species. Bark samples from 25 trees were used to prepare 418 moist chamber cultures maintained and observed 4 wk. Eighty-four myxomycete species were identified, including 30 species not known to occur in the park. Tree species, pH, height in tree and water-holding capacity of the bark samples were analyzed to determine the relationships of myxomycete assemblages cultured on the bark. Results suggested that myxomycete community composition among selected tree species were similar, but occurrence and abundance of certain species were related to differences in bark pH. Community similarity values among trees of different species show that trees with the most similar myxomycete communities also have the most similar bark pH. Most myxomycete species in this study have a pH optimum. No variation in species richness was detected at different heights in the trees, and most species were obtained at all heights up to at least 24 m. The water-holding capacity of the bark could not be correlated with species richness or abundance of myxomycetes that inhabit the bark of living trees. This is the first study to characterize myxomycete communities of tree canopies.     

Stomatal behavior of ozone-sensitive and -insensitive coneflowers (Rudbeckia laciniata var. digitata) in Great Smoky Mountains National Park

* Morphological and physiological attributes were assessed to elucidate the underlying mechanisms of ozone (O(3)) sensitivity in a highly sensitive species, cutleaf coneflower (Rudbeckia laciniata var. digitata). * Foliage at the same height in the canopy on paired O(3)-sensitive and -insensitive cutleaf coneflowers was assessed for level of foliar symptoms, stomatal density, stomatal responsiveness to dynamic changes in light and leaf-to-air vapor pressure deficit (VPD), steady-state responses to light and CO(2), intrinsic transpirational efficiency, and plant water balance. * There were no morphological differences between the sensitivity types that might have contributed to greater O(3) uptake in sensitive individuals. Stomata of sensitive plants were less responsive than those of insensitive plants to experimentally increased and decreased light intensities, and to increased VPD. O(3)-insensitive plants had greater intrinsic transpirational efficiencies, greater maximum assimilation rates under saturating CO(2) and light, and greater carboxylation rates. * Different physiological attributes vary independently within an individual plant, which collectively confer sensitivity or insensitivity to O(3) injury.     

Carex fumosimontana (Cyperaceae), a new endemic from the Great Smoky Mountains National Park, North Carolina and Tennessee

Carex fumosimontana (Great Smoky Mountain Sedge), a new and narrowly endemic species of section Phacocystis, is described from the southern Appalachian Mountains of North Carolina and Tennessee, in the southeastern United States. It differs from the closely related C. gynandra in its dark reddish-brown pistillate scales that are strongly retuse apically, shorter spikes, narrower leaves, and strongly red-scabrous proximal sheath faces. It is locally abundant and sometimes the dominant sedge where it occurs in spite of being completely restricted to high-elevation spruce-fir forests and associated environs of Great Smoky Mountains National Park.     

A Large-scale, Multihabitat Inventory of the Phylum Tardigrada in the Great Smoky Mountains National Park, USA: A Preliminary Report

An All Taxa Biodiversity Inventory (ATBI) is underway in the Great Smoky Mountains National Park (GSMNP), with the goal of attempting to identify all species of life in the 2000 km² park. The GSMNP is a hotbed of biodiversity, a U.N. Biosphere Reserve, and one of the largest protected, deciduous forests in the temperate world. We have completed two field seasons of work on the tardigrades in the park (2001–2002). As of July 2003, we have collected 420 samples from soil/decomposed leaf litter, lichens and mosses on trees, and stream sediment and periphyton. A few samples from caves, bird nests, and lichens/mosses on rocks were also collected. Samples were taken from within permanent plots established for the ATBI, representing the major biological communities of the GSMNP. Tardigrades were extracted from samples using centrifugation with Ludox AM™, individually mounted on microscope slides in Hoyer’s medium, and studied with phase contrast and DIC microscopy. We have examined 1524 slides from 60 samples as of July 2003. Prior to our work, only three species of tardigrades had been previously reported from a few samples in the park. We have now recorded 42 species, 8 of which we believe may be new to science. Species richness estimates were calculated using EstimateS 6 software for each of the major tardigrade habitats. Overall, we predict that there are 47 to 76 species in the GSMNP, with generally similar species richness in soil, lichen, moss, and stream habitats. Species richness estimates were also used to determine that the number of tardigrade species was greater in mosses at breast height on trees than in mosses at the base of trees.     

The influence of logging and topography on the distribution of spruce-fir forests near their Southern limits in Great Smoky Mountains National Park,USA

We studied the effects of logging history, topography, and potential insolation on the lower-elevation limit of existing spruce-fir forest in Great Smoky Mountains National Park (GRSM). Dummy-variable regression, analysis of variance, and classification trees were applied to environmental data within a geographic information system framework. The effect of logging history on the lower limit of spruce-fir depended on aspect. On north-facing slopes (270°– 90°), the presence of spruce-fir was independent of both logging history and potential insolation. On south-facing sites (90°–270°), the elevation of spruce-fir was significantly higher (by 122 m) in areas that had been logged historically. Classification-tree models suggested an even greater logging effect, indicating that both the lower limit and the upper dominance zone of spruce-fir forest are, on average, nearly 200 m higher in historically logged landscapes. Presence of spruce-fir on south aspects was also significantly related to potential insolation, but the strength of this effect was not dependent on logging history. Classification-tree models, developed separately using data from logged sites versus unlogged sites, were used to estimate the current area of spruce-fir forest in the park expected under the hypothetical scenario that no spruce-fir had been logged (38,675 ha) versus the alternate scenario that it had hall been logged (11,727 ha). At present the area of spruce-fir forest in the park is 21,242 ha. We found greater prevalence of spruce-fir on the Tennessee side of the divide on south aspects and historically logged sites, possibly due to greater occurrence of westerly winds and associated cloud cover.     

Neophylax kolodskii (Trichoptera: Uenoidae), A New Species from the Great Smoky Mountains National Park,U.S.A.

Neophylax kolodskii sp. n. from Great Smoky Mountains National Park is described and illustrated from adult specimens.     

Disturbance and vegetation response in relation to environmental gradients in the Great Smoky Mountains

In constructing models of species and community distributions along environmental gradients in the Great Smoky Mountains, R. H. Whittaker (1956) focused on old-aged, apparently stable, natural communities. More recent studies indicate that disturbance gradients potentially influence and are influenced by the complex environmental gradients of Whittaker's original models. Using primarily fire and exotic species invasion as examples, this paper shows: 1) disturbance parameters vary along the topographic, elevation and moisture gradients in the Great Smoky Mountains in much the same way as temperature, moisture and solar radiation change; 2) species composition at different locations along the major environmental gradients is partially determined by the disturbance parameter; 3) species characteristics such as mode of reproduction are often correlated with specific disturbance parameters; 4) functional aspects of ecosystem response to disturbance vary along environmental gradients; and 5) man-caused disturbance may vary along environmental or biotic gradients. Since disturbance gradients may parallel physical environmental gradients, the two may be difficult to distinguish. Modification of disturbance frequencies along major environmental gradients may result in slow shifts in the distribution of both individual species and whole communities.Botanical nomenclature follows Radford et al. (1968).