Southern Appalachian Streams Research Articles

Differing Effects of Restoration and Habitat Enhancement in Four Southern Appalachian Streams

Differing Effects of Restoration and Habitat Enhancement in Four Southern Appalachian Streams

Have stream diatom assemblages changed a decade after the loss of a foundation riparian tree species in a headwater Appalachian watershed?

Terrestrial and stream ecosystems are interconnected, with changes in one system cascading to affect the other. Tree mortality related to nonnative pest infestation has increased, yet we do not understand the effects that riparian tree species losses will have on the structural characteristics of stream ecosystems. We compared riparian canopy cover, algal standing crop, and diatom assemblage composition in 8 southern Appalachian headwater stream reaches within the Coweeta Hydrologic Laboratory in North Carolina, USA, before and after a massive die-off of riparian eastern hemlock (Tsuga canadensis [L.] Carr.) related to the introduction of hemlock woolly adelgid (Adelges tsugae Annand), an invasive insect. We analyzed historical preserved algal samples collected prior to hemlock die-off, in both summer (September 2005) and winter (January 2006), and used multivariate analyses to compare them to samples collected in the same 8 reaches and seasons 13 y following hemlock die-off (2018–2019). We predicted that increased canopy openness following hemlock death would change light availability and lead to higher standing crop and increases in the relative biovolume of high-profile diatoms. Contrary to our expectations, we found little difference in canopy cover and lower algal standing crop 13 y post-hemlock die-off, likely due to increased basal area of the understory shrub, Rhododendron maximum L., that replaced shade cover formerly provided by hemlock. Diatom assemblages were dominated by acidophilic taxa (e.g., Eunotia spp.) across all stream reaches before and after hemlock die-off. We observed some shifts in diatom assemblage composition, but the relative biovolume of a majority of the top 20 most abundant taxa, including Eunotia incisa W. Sm. ex W. Greg., Nupela lapidosa (Krasske) Lange-Bert., and Meridion alansmithii Brant (an endemic taxon), remained relatively unchanged 13 y after hemlock mortality. Diatom assemblages differed post-hemlock die-off in summer but not winter due to a decrease in the relative biovolume of Eunotia metamondon complex and an increase in the relative biovolume of Eunotia rhomboidea complex. Our study highlights the relative stability of diatom assemblage composition in southern Appalachian streams and the importance of long-term studies following a major riparian disturbance.

A test of a generalized, optimal habitat selection model for drift‐feeding fishes: brook charr

AbstractOptimality theory is useful for modeling habitat use in animals, although many models have not been rigorously tested. We evaluated the ability of the Grossman et al. net‐energy‐intake (NEI) optimal foraging model for drift‐feeding stream fishes, to predict the holding velocity (microhabitat) of native brook charr (BC; Salvelinus fontinalis) inhabiting a southern Appalachian stream. This model postulates that fish choose holding velocities that maximize their NEI, and is broadly applicable to stream fishes, many of which are drift‐feeders. We used laboratory prey capture success versus water velocity data to quantify the relationship between prey capture success, water velocity, and holding velocity of BC (N = 21, mean standard length = 147 mm ± 14 sd). Parameterization of the Grossman et al. model yielded an optimal holding velocity prediction of 18.5 cm·s−1. Based on fitting criteria from previous work, the model prediction was successful because it fell within the 95% confidence interval (13.5–20.5 cm·s−1) of mean holding velocities (17.0 cm·s−1, N = 26) of BC in Lynn Camp Prong, Tennessee. Consequently, NEI maximization likely is a causal factor affecting BC habitat choice. Our result argues strongly for the general usefulness of this model.

Not all methods are created equal: assessment of sampling methods for crayfishes and fishes in southern Appalachian streams

We compared the effectiveness of three sampling methods (kick seining, electrofishing, and nest trapping) to collect crayfishes and fishes, simultaneously, in southern Appalachian Mountain streams (Alabama, USA). For crayfishes, kick seining collected the highest species richness and most individuals. However, by combining kick seining and electrofishing collections, we decreased the number of sites needed to accurately assess crayfish richness relative to using one method. For 9 of the 13 species collected, no differences in crayfish sizes or sex ratios were detected between electrofishing and kick seining. In the remaining four species, electrofishing collected larger crayfishes and more females than kick seining. For fishes, electrofishing was most effective at assessing fish species richness. Sampled fish richness was higher when electrofishing in streams with higher water temperatures and width-to-depth ratios, as well as lower conductivities and smaller substrates. Electrofishing was the most effective sampling method for collecting Centrarchids, whereas kick seining was most effective at collecting Cyprinids. Nest traps were the least effective sampling method. We conclude that using a combination of kick seining and electrofishing is best for assessing stream fish and crayfish assemblages, simultaneously, which can improve management, biomonitoring, and understanding of the complex relationships between these faunal groups.

Removing riparian Rhododendron maximum in post-Tsuga canadensis riparian forests does not degrade water quality in southern Appalachian streams

In the past century, the evergreen woody shrub, Rhododendron maximum, has experienced habitat expansion following foundational tree species die-off in eastern US deciduous forests. Rhododendron can potentially alter stream chemistry, temperature, trophic dynamics, and in-stream decomposition rates, given its dominance in riparian areas. Here we conducted two operational-scale (3 ha) riparian treatments that removed rhododendron through cutting alone (CR, canopy removal), or removing both the rhododendron canopy and forest floor using cutting and prescribed fire (CFFR, canopy and forest floor removal). We expected that rhododendron shrub removal, with or without soil organic horizon removal, would increase soil nutrient availability and subsequently alter stream pH, acid neutralizing capacity (ANC), inorganic nitrogen (NO3-N, NH4-N), total dissolved inorganic nitrogen, dissolved organic carbon (DOC), calcium (Ca), potassium (K), and magnesium (Mg). We hypothesized that responses would occur more quickly in the CFFR treatment. Treatments reduced shrub-, but not tree basal area. Treatments lowered soil N, but not C. Stream chemistry responses to treatments varied between CR and CFFR and were transient, generally with pH, N, and some cations declining, and aluminum (Al) and DOC showing a pulse increase. By removing rhododendron, the remaining deciduous trees likely accelerated N uptake as soil moisture availability increased. This could partially explain why we observed lower than expected stream nutrients (NO3-N, Ca, and Mg) after treatments. Initial rhododendron slash on the forest floor coupled with incomplete consumption of the O-horizon on the CFFR treatment likely elevated DOC in the upper soil horizons and mobilized Al. From a management perspective, using these treatments to restore structure and function to riparian forests in the wake of eastern hemlock mortality, with or without fire, would most likely not result in short-term diminished water quality that is common when overstory trees are harvested and may even lower stream NO3-N concentrations long term.

Stocked rainbow trout (Oncorhynchus mykiss) affect space use by Warpaint Shiners (Luxilus coccogenis)

AbstractDue to widespread stocking, Rainbow Trout (Oncorhynchus mykiss Walbaum) are perhaps the most widely distributed invasive species in the world. Nonetheless, little is known about the effects of stocked Rainbow Trout on native non‐game species. We conducted experiments in an artificial stream to assess the effects of hatchery Rainbow Trout on home range and behaviour of Warpaint Shiners (Luxilus coccogenis Cope), a common minnow frequently found in stocked Southern Appalachian streams. We used the LoCoH algorithm to generate polygons describing the home ranges used by Warpaint Shiners. When a stocked trout was present Warpaint Shiners: (a) increased home range size by 57%, (b) were displaced into higher velocity mesohabitats, and (c) reduced mean overlap between the home ranges of individual warpaint shiners. Rainbow Trout did not significantly affect the edge/area ratio of Warpaint Shiner home ranges. Warpaint Shiner density (two and five fish treatments) did not significantly affect any response variable. Displacement from preferred microhabitats and increases in home range size likely result in increased energy expenditure and exposure to potential predators (i.e., decreased individual fitness) of Warpaint Shiners when stocked trout are present.

Multiple drivers, scales, and interactions influence southern Appalachian stream salamander occupancy

AbstractUnderstanding how factors that vary in spatial scale relate to population abundance is vital to forecasting species responses to environmental change. Stream and river ecosystems are inherently hierarchical, potentially resulting in organismal responses to fine‐scale changes in patch characteristics that are conditional on the watershed context. Here, we address how populations of two salamander species are affected by interactions among hierarchical processes operating at different scales within a rapidly changing landscape of the southern Appalachian Mountains. We modeled reach‐level occupancy of larval and adult black‐bellied salamanders (Desmognathus quadramaculatus) and larval Blue Ridge two‐lined salamanders (Eurycea wilderae) as a function of 17 different terrestrial and aquatic predictor variables that varied in spatial extent. We found that salamander occurrence varied widely among streams within fully forested catchments, but also exhibited species‐specific responses to changes in local conditions. While D. quadramaculatus declined predictably in relation to losses in forest cover, larval occupancy exhibited the strongest negative response to forest loss as well as decreases in elevation. Conversely, occupancy of E. wilderae was unassociated with watershed conditions, only responding negatively to higher proportions of fast‐flowing stream habitat types. Evaluation of hierarchical relationships demonstrated that most fine‐scale variables were closely correlated with broad watershed‐scale variables, suggesting that local reach‐scale factors have relatively smaller effects within the context of the larger landscape. Our results imply that effective management of southern Appalachian stream salamanders must first focus on the larger scale condition of watersheds before management of local‐scale conditions should proceed. Our findings confirm the results of some studies while refuting the results of others, which may indicate that prescriptive recommendations for range‐wide management of species or the application of a single management focus across large geographic areas is inappropriate.

In-stream habitat predicts salamander occupancy and abundance better than landscape-scale factors within exurban watersheds in a global diversity hotspot

The southern Appalachian Mountains have experienced rapid human population growth rates since the 1980s. Land used practices are shifting from rural to residential. The majority of development has been low density, and is often near biologically diverse areas such as National Forests and National Parks. The long-term effects of urbanization in the southeastern Appalachian Mountains are not clearly understood and even less is known with respect to stream salamander response to urbanization. In order to determine the temporal influence of exurban housing on southern Appalachian streams we sampled 27 first- and second-order streams in watersheds containing exurban developments ranging in age from 4 to 44 years, along with eight forested streams, over the course of two summers. We sought to determine if the relative age of an exurban development related to occupancy and abundance of southern Appalachian stream salamanders. Age of exurban development and other watershed scale variables were not top predictors of salamander assemblages, while local site variables such as salinity and undercut banks predicted the abundance of several species of salamander. Our results suggest local habitat improvements can be used to better conserve salamanders and stream ecosystems in an increasingly urbanized region.

Fish assemblage production estimates in Appalachian streams across a latitudinal and temperature gradient

AbstractProduction of biomass is central to the ecology and sustainability of fish assemblages. The goal of this study was to empirically estimate and compare fish assemblage production, production‐to‐biomass (P/B) ratios and species composition for 25 second‐ to third‐order streams spanning the Appalachian Mountains (from Vermont to North Carolina) that vary in their temperature regimes. Fish assemblage production estimates ranged from 0.15 to 6.79 g m−2 year−1, and P/B ratios ranged from 0.20 to 1.07. There were no significant differences in mean assemblage production across northern cold‐water, southern cold‐water and southern cool‐water streams (p = .35). Two warm‐water streams, not included in these comparisons, had the highest mean production and biomass values. Mean assemblage P/B was significantly higher in northern cold‐water streams relative to southern cold‐water and cool‐water streams (p = .01). Species evenness in production declined with stream temperature and differed significantly across the lower latitude cold‐water, cool‐water and warm‐water streams and the higher latitude (i.e. more northern) cold‐water streams. Our fish assemblage production estimates and P/B ratios were both lower and higher compared to previously published estimates for similar stream habitats. This study provides empirical fish assemblage production estimates to inform future research on southern Appalachian streams and on the potential impacts of varying temperature regimes on cold‐water, cool‐water and warm‐water fish production in the coming decades as climate change continues to threaten fish assemblages.

Effects of coal mining, forestry, and road construction on southern Appalachian stream invertebrates and habitats.

Coal has been extracted via surface and sub-surface mining for decades throughout the Appalachian Mountains. New interest in ridge-top mining has raised concerns about possible waterway impacts. We examined effects of forestry, mining, and road construction-based disturbance on physico-chemistry and macroinvertebrate communities in east-central Tennessee headwater streams. Although 11 of 30 sites failed Tennessee's biocriteria scoring system, invertebrate richness was moderately high and we did not find significant differences in any water chemistry or habitat parameters between sites with passing and failing scores. However, conductivity and dissolved solid concentrations appeared elevated in the majority of study streams. Principal components (PCs) analysis indicated that six PCs accounted for ~77% of among-site habitat variability. One PC associated with dissolved oxygen and specific conductance explained the second highest proportion of among-site variability after catchment area. Specific conductance was not correlated with catchment area but was strongly correlated with mining activity. Composition and success of multivariate models using habitat PCs to predict macroinvertebrate metrics was highly variable. PC scores associated with water chemistry and substrate composition were most frequently included in significant models. These results suggest that impacts of historical and current coal mining remain a source of water quality and macroinvertebrate community impairment in this region, but effects are subtle. Our results suggest that surface mining may have chronic and system-wide effects on habitat conditions and invertebrate communities in Cumberland Plateau streams.

Invasive rainbow trout affect habitat use, feeding efficiency, and spatial organization of warpaint shiners

Rainbow trout have been introduced to six of the seven continents and currently are widely stocked for sport fishing. Despite their broad distribution, outside of New Zealand, little is known about the effects of rainbow trout on native species, especially fishes. We conducted experiments in an artificial stream to assess hypotheses that stocked rainbow trout significantly affected: (1) mesohabitat use, (2) foraging success, (3) social behavior, and (4) spatial organization of warpaint shiners (Luxilus coccogenis) a common native minnow found in southern Appalachian streams, with similar patterns of microhabitat use to rainbow trout. We replicated experiments at high and low natural densities (two and five warpaint shiners) and spring/fall (12 °C) and summer (17 °C) temperatures. Treatments included: (1) a control (five warpaint shiners), (2) trout (five warpaint shiners and one rainbow trout), (3) large fish control (five warpaint shiners and one river chub) and (4) density control (six warpaint shiners). The presence of rainbow trout produced a shift by warpaint shiners from pool mesohabitats to shallower, higher velocity habitats with more variable substrata, as well as reduced prey capture success, feeding efficiency, and distance from the front of the tank (i.e., warpaint shiners moved closer to food release points), and increased the distance to the additional fish (i.e., avoidance of the rainbow trout). Negative effects on foraging behaviors were stronger in 12 °C treatments. In a realistic stream flume the presence of rainbow trout produced effects that likely influenced individual fitness of warpaint shiners. The potential effects of stocking rainbow trout on native non-game fishes, such as warpaint shiners should be assessed when implementing or evaluating stocking programs.

Input matching and patch use by native and invasive minnows

AbstractWhen members of a population choose patches that maximise individual net energy gain without interference, they are input matching, a strategy derived from the ideal free distribution (IFD) that results in equal rewards across all patches. We investigated the input matching abilities of yellowfin shiner, a recent invader, and rosyside dace, a common native minnow, found in Coweeta Creek, North Carolina, USA. To test the species' relative input matching abilities, we varied food abundance within the range found in the natural habitat in a two‐patch laboratory stream to document the distribution of foragers when food densities differed in the ratio of 2:1. We then applied simple IFD model predictions to determine whether the observed distribution of foragers was best described by (i) the IFD, (ii) differing competitive abilities or (iii) the ideal despotic distribution and/or other unequal competitor models, and to ascertain whether the invader demonstrated a superior ability to track resource distributions. Yellowfin shiner was more likely to move between patches, which resulted in increased ability to match the distribution of food when prey abundance increased. The distribution of rosyside dace between patches did not change in response to increased food abundance. Despite a considerable range of competitive abilities within intraspecific groups, the ‘equal competitors’ IFD was as good at predicting fish distributions as ‘unequal competitor’ models. The ability to track local resource availability in highly variable environments facilitates maximising energy intake and likely promoted the establishment of yellowfin shiner in a southern Appalachian stream.

Effects of Hemlock Mortality on Streams in the Southern Appalachian Mountains

The death of eastern hemlock (Tsuga canadensis) trees in response to infestation by the introduced hemlock woolly adelgid (Adelges tsugae) may affect ecosystem processes and structure of streams. Prior to hemlock mortality, we documented the conditions of eight small streams and their associated riparian forests within the Appalachian Mountains of North Carolina, U.S.A. Hemlock was the dominant tree species on all riparian sites and was always associated with rhododendron (Rhododendron maximum). Significant trends of increasing canopy openness, increasing light to the streams and increasing annual temperature range were observed. Contributions of hemlock to litterfall, in-stream wood, and benthic organic matter were important at the beginning of the study, suggesting that the loss of hemlock may significantly modify the trophic dynamics and physical structure of southern Appalachian streams. Increased growth of rhododendron in response to hemlock mortality may compensate for the trophic influences of hemlock loss. However, because of rhododendron's negative effect on growth of seedlings of other tree species, the greatest ecosystem impact of hemlock wooly adelgid may be more extensive rhododendron thickets within the riparian corridors of southern Appalachian streams.

Growth, pH Tolerance, Survival, and Diet of Introduced Northern‐Strain and Native Southern‐Strain Appalachian Brook Trout

AbstractThe native range of brook trout Salvelinus fontinalis in southern Appalachia has been drastically reduced by human activities over the last century. Restoration of brook trout populations was attempted through stocking of hatchery‐reared fish that were derived from populations native to northern Appalachia; these northern brook trout are genetically distinct from populations native to southern Appalachia. The extent of ecological differences between the naturalized, hatchery‐derived northern brook trout (NBKT) and native southern brook trout (SBKT) is unknown but may have important implications for southern Appalachian stream ecosystems. We used a combination of laboratory, outdoor raceway, and natural stream experiments to test for differences in growth, pH tolerance, survival, and diet between introduced NBKT and native SBKT. Fish were collected separately for each experiment from wild allopatric populations in North Carolina. Northern brook trout had higher average survival than SBKT in the laboratory and raceway experiments, although the difference was significant only in the laboratory experiment. Northern brook trout had higher growth rates in the laboratory regardless of pH treatment, but growth was similar between strains in the raceway experiment. Relative condition factor was reduced by low pH, regardless of strain. Diets differed between the two strains in the natural stream experiment; NBKT consumed a larger percentage of terrestrial insects than did SBKT. These data offer the first experimental evidence of genetically based ecological differences between pure strains of wild, hatchery‐derived NBKT and native SBKT in southern Appalachia.

Changes in light levels and stream temperatures with loss of eastern hemlock (Tsuga canadensis) at a southern Appalachian stream: Implications for brook trout

The exotic invasive insect, hemlock woolly adelgid (Adelges tsugae Annand), is causing mortality in eastern hemlocks (Tsuga canadensis [L.] Carr.) throughout the eastern U.S. Because hemlocks produce dense shade, and are being replaced by hardwood species that produce less shade, their loss may increase understory light levels. In the southern Appalachians, increases in light could increase stream temperatures, threatening species such as brook trout (Salvelinus fontinalis). We studied changes in light and stream temperature with eastern hemlock decline at a headwater southern Appalachian brook trout stream. Our results indicate that stream light levels have increased significantly with adelgid infestation. Leaf-on light levels are currently significantly higher (P<0.02) in plots containing high basal areas of hemlock (mean global site factor (GSF)(SE)=0.267(0.01)) compared with plots containing no hemlock (mean GSF(SE)=0.261(0.01)), suggesting that increases in light have occurred with hemlock decline. The Normalized Difference Vegetation Index (NDVI), a remotely sensed metric of vegetation density, decreased with hemlock decline from 2001 to 2008. In 2001, NDVI showed no relationship (R2=0.003; F=0.14; P=0.71) with hemlock basal area, but by 2008, there was a significant negative relationship (R2=0.352; F=19.55; P<0.001) between NDVI and hemlock basal area. A gap experiment showed that light levels may increase by up to 64.7% more (mean increase in GSF=27.5%) as hemlocks fall, creating gaps in the canopy. However, stream temperatures did not increase with hemlock decline during the study period, and we found that ground water inputs have a stronger influence on water temperature than light levels at this site. Linear regression showed a significant negative relationship between water temperature and proximity to ground water sources (R2=0.451; F=13.14; P=0.002), but no relationship between water temperature and light levels (R2<0.02; P>0.05). In addition, by comparing light levels between plots containing hemlock and those containing only hardwoods, we found that if hemlocks are replaced by hardwoods, light levels under an all-hardwood canopy (mean GSF(SE)=0.240(0.005)) are unlikely to be higher than they are under the current forest (mean GSF(SE)=0.254(0.007)). These results suggest that loss of hemlock along southern Appalachian headwater streams could have short-term impacts on light levels, but that long-term changes in light levels, increases in water temperature, and adverse effects on brook trout may be unlikely.

Three‐Pass Depletion Sampling Accuracy of Two Electric Fields for Estimating Trout Abundance in a Low‐Conductivity Stream with Limited Habitat Complexity

AbstractWe evaluated three‐pass depletion sampling for both AC and pulsed‐DC electrofishing for estimating the population size of rainbow trout Oncorhynchus mykiss in a representative low‐conductivity (20‐μS/cm) southern Appalachian stream with limited habitat complexity. Trout capture efficiencies in such streams could be expected to exceed those observed in streams in which habitat is more complex; thus, depletion estimates could be much more accurate in the former. We also compared the results for two trout length‐groups to investigate size‐related differences. Measured capture efficiency was 0.88 ± 0.04 (95% confidence interval) for trout greater than 100 mm (typically adults) and 0.65 ± 0.09 for trout less than 100 mm (age 0). Population size was underestimated in each depletion sample. The errors for trout over 100 mm were generally small (mean, 12%; range, 3–23%), and the upper 95% confidence limits were usually within 10% of the true population size (N). Underestimates of N were larger for trout under 100 mm (mean, 32%; range, 5–60%), although the upper 95% confidence limits were within 20% of the N for half of the samples. The results of a laboratory study confirmed that trout over 100 mm were immobilized at significantly lower voltage gradients than were smaller trout in both electric fields. We conclude that three‐pass depletion sampling is relatively accurate in typical southern Appalachian trout streams and that the underestimation errors for rainbow trout larger than 100 mm would be acceptable given basic inventory and monitoring goals.

Turbidity, velocity and interspecific interactions affect foraging behaviour of rosyside dace (Clinostomus funduloides) and yellowfin shiners (Notropis lutippinis)

Abstract – Fish diversity is strongly affected by habitat degradation (e.g., increased turbidity) and invasive species. We examined the effects of turbidity, velocity, length, dominance and intra‐ and interspecific competition on focal point depth, movement rate, dominance and aggression rate in native rosyside dace (Clinostomus funduloides) and invasive yellowfin shiners (Notropis lutipinnis) in a southern Appalachian stream (NC, USA). We compared results for intra‐ and interspecific groups of fishes at two densities (two and four fishes), three turbidity levels (10, 20 and 30 nephelometric turbidity units), and two velocities (12, 18 cm·s−1). Dominance was significantly correlated with length in intraspecific groups of both species, and dominant fish held more profitable foraging positions about 75% of the time. Yellowfin shiners were dominant more often than rosyside dace in interspecific trials. Akaike’s Information Criterion indicated that models containing turbidity, velocity, species and intraspecific competition, explained the greatest amount of information in focal point depth data. By contrast, movement and aggression rates were best explained by models based on dominance and velocity. Finally, aggression rate was best explained by models containing fish length and turbidity. These results indicate that habitat degradation, intra‐ and interspecific interactions influence the foraging behaviour and future success of these species in the Little Tennessee River drainage.

Quantifying microhabitat availability: stratified random versus constrained focal-fish methods

During a study of microhabitat use by gilt darters (Percina evides), we compared two methods for quantifying microhabitat availability in a southern Appalachian stream (USA). The first method used stratified random sampling throughout the site and the second involved taking constrained random measurements within a 2-m radius of the focal fish. Darters were generally over-represented in microhabitats with higher average velocities, greater amounts of erosional substrata, and lower amounts of depositional and large substrata. The two methods generally yielded similar patterns of microhabitat use. Nonetheless, of the seven microhabitat categories in which differential microhabitat use occurred in summer, four were present in both data sets, but three differed between methods. We observed no differences between methods for autumn data. Finally, the standard deviations of the summer-stratified random data set were significantly greater (sign test, P < 0.05) than those of the constrained data set. Our results suggest that either method for quantifying microhabitat availability can be used to quantify the general habitat use patterns of this species, but constrained analyses yielded a more restricted view of the total habitat available. Nonetheless, if the fishes range over a site, clearly stratified habitat availability analysis is preferred.

Post‐disturbance effects of even‐aged timber harvest on stream salamanders in southern Appalachian forests

AbstractHabitat degradation and fragmentation has received increased attention in the past 15 years as a primary factor responsible for the decline of many species of wildlife including amphibians. In the eastern USA many of the studies have focused on fully terrestrial plethodontid salamanders, while information on stream‐breeding plethodontids remains relatively lacking. Using two different survey methods (area‐constrained daytime searches and night‐time visual encounter searches), we estimated terrestrial habitat use and abundance for stream‐breeding salamanders in three different tree stand age‐classes in southern Appalachian streams from May to August 2005. We found that overall stream salamander abundance and terrestrial habitat use was reduced in stands &lt;40 years of age compared with stands 41–80 years old, and &gt;81 years old. The decreased abundance and terrestrial habitat use was accompanied by a decrease in leaf litter depth, soil moisture and canopy cover. The Blue Ridge two‐lined salamander Eurycea wilderae was the most affected salamander in the assemblage and we conservatively estimate at least a 40‐year recovery period for the assemblage to return to pre‐disturbance levels. To protect stream amphibians, alternative silvicultural practices such as uneven‐aged timber harvest (e.g. selective harvesting) must be considered.

Abiotic factors influencing abundance and microhabitat use of stream salamanders in southern Appalachian forests

In order to evaluate the effects of habitat loss and degradation on amphibian populations it is necessary to determine species-specific habitat use and how this influences abundance. While a number of studies have examined the influence of competition and predation in stream salamander assemblages in the southern Appalachian Mountains, there remains a relative lack of knowledge on the microhabitat use of these species. Using area-constrained daytime searches, we investigated microhabitat use and abundance for stream-breeding salamanders in mature forests in southern Appalachian streams from May to August 2004. We found that leaf litter depth, soil moisture, and canopy cover were all higher and soil temperature was lower in plots where stream salamanders were encountered compared to plots where salamanders were not encountered. A regression analysis using the information-theoretic approach (AIC) revealed that the model that included distance from stream, leaf litter depth, soil moisture, and soil temperature had the strongest support for predicting stream salamander abundance at the landscape level ( ω i = 0.99). Microhabitat use in many species of stream salamanders is mediated by a number of complex factors including environmental variables, competition, and predation. Alteration of habitats likely results in increased competition and predation rates and subsequent local population declines, so it is imperative to mitigate the effects of practices such as even-aged timber harvesting in order to conserve amphibian biodiversity.