Amphibian Use of Wetlands Created by Military Activity in Kisatchie National Forest, Louisiana, USA.

Constructed wetlands can provide breeding habitat for amphibians and might offset the loss of natural wetlands. Although protecting natural systems is a priority, investigating and protecting constructed wetlands should also be included in amphibian conservation efforts. We surveyed 48 small wetland pools created from military tank training (i.e., tank defilades) on Kisatchie National Forest, Louisiana, USA. We conducted surveys monthly from April to October 2012 and March to September 2013. Across both years amphibian communitycomposition consisted of eight frog species, and the most commonly found taxa were Cajun Chorus Frogs (Pseudacris fouquettei), Southern Leopard Frogs (Lithobates sphenocephalus), and Bronze Frogs (Lithobates clamitans), with their larvae occurring in 85%, 81%, and 19% of pools, respectively. General linear models showed that Cajun Chorus Frog use of pools for breeding was best explained by absence of fish. The environmental factors that explained larval abundance differed between years but included absence of fish, temporary hydroperiod, open canopy, and a positive association with pH. Hydrology and conductivity best explained Southern Leopard Frog abundance. Bronze Frog presence was best explained by absence of fish and wetland slope. We did not capture other species in sufficient frequency for linear modeling, but their presence varied in response to hydroperiod, as shown by differences in similarity indices when comparing community composition between permanent and temporary pools. Our results highlight the importance of a mosaic of pool conditions and demonstrate that military activity, specifically creation of tank defilades, appears to benefit local amphibian species. Further research is required to examine larval survival and determine if any pools should be restructured to protect and create amphibian breeding habitat

Integrated control-system design via generalized LQG (GLQG) theory

Thirty years of control systems research has produced an enormous body of theoretical results in feedback synthesis. Yet such results see relatively little practical application, and there remains an unsettling gap between classical single-loop techniques (Nyquist, Bode, root locus, pole placement) and modern multivariable approaches (LQG and H infinity theory). Large scale, complex systems, such as high performance aircraft and flexible space structures, now demand efficient, reliable design of multivariable feedback controllers which optimally tradeoff performance against modeling accuracy, bandwidth, sensor noise, actuator power, and control law complexity. A methodology is described which encompasses numerous practical design constraints within a single unified formulation. The approach, which is based upon coupled systems or modified Riccati and Lyapunov equations, encompasses time-domain linear-quadratic-Gaussian theory and frequency-domain H theory, as well as classical objectives such as gain and phase margin via the Nyquist circle criterion. In addition, this approach encompasses the optimal projection approach to reduced-order controller design. The current status of the overall theory will be reviewed including both continuous-time and discrete-time (sampled-data) formulations

Species Interactions in Constructed Wetlands Result in Population Sinks for Wood Frogs (Lithobates sylvaticus) while Benefitting Eastern Newts (Notophthalmus viridescens)

Wetland construction has been used as a tool to mitigate wetland loss, but constructed wetlands might not provide the same functions as natural wetlands. Hundreds of long-hydroperiod wetlands have been constructed within the Daniel Boone National Forest, Kentucky, in a ridge-top ecosystem where natural wetlands dry annually (i.e., have short hydroperiods). The constructed wetlands have been colonized by several amphibian species not historically associated with this ecosystem and that could have negative impacts on native amphibian species. We compared wood frog (Lithobates sylvaticus) reproductive success at constructed and natural wetlands and benefits of wood frog presence in constructed wetlands to eastern newts (Notophthalmus viridescens). Wood frog reproductive success was zero when eggs were laid in constructed wetlands: 7–70 % of eggs were consumed and no wood frog larvae were found. Eastern newts, present at all constructed wetlands, benefited from wood frog presence, i.e., newts in constructed wetlands with wood frog eggs had higher body condition than newts in natural wetlands. Wetland construction techniques should be altered so their hydrology mimics that of natural wetlands to support historically occurring species. Understanding the influence of species interactions, as habitat loss and modification increase, will continue to be critical for amphibian conservation. Keywords Ephemeral wet

Environmental Gradients in Old‐Growth Appalachian Forest Predict Fine‐Scale Distribution, Co‐occurrence, and Density of Woodland Salamanders

Woodland salamanders are among the most abundant vertebrate animals in temperate deciduous forests of eastern North America. Because of their abundance, woodland salamanders are responsible for the transformation of nutrients and translocation of energy between highly disparate levels of trophic organization: detrital food webs and high‐order predators. However, the spatial extent of woodland salamanders’ role in the ecosystem is likely contingent upon the distribution of their biomass throughout the forest. We sought to determine if natural environmental gradients influence the fine‐scale distribution and density of Southern Ravine Salamanders (Plethodon richmondi) and Cumberland Plateau Salamanders (P. kentucki). We addressed this objective by constructing occupancy, co‐occurrence, and abundance models from temporally replicated surveys within an old‐growth forest in the Cumberland Plateau region of Kentucky. We found that Plethodon richmondi had a more restricted fine‐scale distribution than P. kentucki (mean occupancy probability [] = 0.737) and exhibited variable density, from \u3c250 to \u3e1000 individuals per hectare, associated with increased soil moisture and reduced solar exposure due to slope face. While more ubiquitously distributed ( = 0.95), P. kentucki density varied from \u3c400 to \u3e1,000 individuals per hectare and was inversely related to increased solar exposure from canopy disturbance and landscape convexity. Our data suggest co‐occurrence patterns of P. richmondi and P. kentucki are influenced primarily by abiotic conditions within the forest, and that populations likely occur independently and without evidence of biotic interaction. Given the critical role that woodland salamanders play in the maintenance of forest health, regions that support large populations of woodland salamanders, such as those highlighted in this study—mesic forest stands on north‐to‐east facing slopes with dense canopy and abundant natural cover, may provide enhanced ecosystem services and support the stability of the total forest

Microhabitat conditions influence mesohabitat associations and distribution of larval salamanders in headwater streams

Distribution patterns of stream biota are the result of complex interactions between individuals and their surrounding environment. Determining the spatial scale by which an organism is most influenced is paramount to understanding distribution patterns. Using a multi-scale approach, we investigated factors influencing habitat associations of larval Ambystoma barbouri (streamside salamander) and Eurycea cirrigera (southern two-lined salamander) in three Kentucky headwater streams. We used likelihood ratio G tests to identify associations between species and mesohabitat (i.e., runs, riffles, and pools), and we used microhabitat variables to predict the presence and abundance of salamanders via a priori multiple regression modeling. Ambystoma barbouri presence and abundance were influenced by conditions at micro-scales, which in turn dictated mesohabitat associations. Eurycea cirrigera were also influenced by microhabitat variables, but displayed associations to A. barbouri presence in late spring. Associations of larval salamanders to mesohabitat and microhabitat parameters shifted from early to late spring, likely in response to changes in developmental stage. The multi-scale approach of our study improved our understanding of complex relationships between larval salamanders and their surrounding environment in headwaters, and underscored the importance of (1) research investigating multiple spatial and temporal scales and (2) heterogeneous in-stream habitat to headwater biota

The Diet of the Cumberland Plateau Salamander (Plethodon kentucki) in an old growth forest of southeastern Kentucky

Examining the diet of salamanders is important for understanding their effects on invertebrate communities and the interactions among sympatric salamander species. We examined the diet of the Cumberland Plateau Salamander, Plethodon kentucki (Mittleman), in an old growth forest in southeastern Kentucky. A total of 763 prey items were recovered from 73 salamanders with an average of 10.75 prey items per stomach. The four most important prey groups were Formicidae (ants), Araneae (spiders), Coleoptera (beetles), and Collembola (springtails). Overall, we found a total of 58 different prey types in the stomach contents from 20 invertebrate orders. This study represents one of the few successful uses of nonlethal gastric lavage methods on a large plethodontid salamander and the first description of P. kentucki diet identified to family and genus. Future work should examine diet throughout the year, compare prey species composition to sympatric salamander species, and look at local prey abundances and diversity to explore salamander foraging behavior

The Diet of the Cumberland Plateau Salamander (Plethodon kentucki) in an old growth forest of southeastern Kentucky

Terrestrial lungless salamanders are known to reach very high densities in forested ecosystems of the United States. They can be important for the top down regulation of invertebrates Diets of 57% (31 of 54) Plethodonsalamanders are still poorly known The Cumberland Plateau Salamander (Plethodon kentucki) is a large plethodontid common in the Central Appalachians, however, its diet is only known from West Virginia DOI: 10.13140/RG.2.2.18118.4768

Diet Composition: A Proximate Mechanism Explaining Stream Salamander Declines in Surface Waters with Elevated Specific Conductivity

Changes in land use, such as mountaintop removal mining with valley fills (MTR-VF), often results in headwater streams with elevated specific conductivity (SC). Stream salamanders appear to be particularly sensitive to elevated SC, as previous studies have shown occupancy and abundance decline consistently among all species and life stages as SC increases. Yet, the proximate mechanism responsible for the population declines in streams with elevated SC have eluded researchers. We sampled salamander assemblages across a continuous SC gradient (30–1966 μS/cm) in southeastern Kentucky and examined the diet of larval and adult salamanders to determine if the ratio of aquatic to terrestrial prey (autochthony), total prey volume, aquatic prey importance (Ix), and body condition are influenced by SC. Further, we asked if threshold points for each diet component were present along a gradient of SC. Larval salamanders experienced a 12–fold decline in autochthony at 153 μS/cm, a 4.2–fold decline in total prey volume at 100 μS/cm, a 2.2-fold decline in aquatic Ix at 135 μS/cm, and a rapid decline in body condition as SC increased. Adult salamanders experienced a 3–fold decline in autochthony at 382 μS/cm, no change in prey volumes, a 2-fold decline in aquatic Ix at 163 μS/cm, and a decline in body condition as SC increased. Our results indicate that SC indirectly affects stream salamander populations by changing the composition of diet, which suggests that food availability is a proximate mechanism that leads to reduced population occupancy, abundance, and persistence in streams with elevated SC

Occupancy and Abundance of Stream Salamanders along a Specific Conductance Gradient

In the Central Appalachians (USA), mountaintop-removal mining accompanied by valley fills often leads to streams with elevated specific conductivity (SC). Thus, the ionic composition of freshwaters in this region is hypothesized to be a driver of the distribution and abundance of freshwater taxa, including stream salamanders. We examined the association between SC and stream salamander populations by conducting salamander counts in 30 southeastern Kentucky streams across a continuous gradient of SC that ranged from 30 to 1966 μS/cm. We counted 2319 salamanders across 5 species and, using a hierarchical Bayesian version of the N-mixture model, found a negative association between SC and salamander occupancy rates. This finding was consistent across adults and larvae of the 5 species we examined. Furthermore, we found that most salamander species and life stages showed reduced abundances given occupancy at greater SC levels. For example, estimated mean abundance given occupancy of larval Southern Two-lined Salamanders (Eurycea cirrigera) was 67.69 (95% credible interval 48.31–98.25) ind/10 m at 250 μS/cm and 2.30 (95% credible interval 1.46–3.93) ind/10 m at 2000 μS/cm. The consistent negative association across all species and life stages supports the hypothesis that salamander distributions and abundances are negatively associated with elevated SC of streams in southeastern Kentucky, even though physical and chemical environmental attributes, such as forest cover within stream catchments, were correlated with SC. Restoration of streams affected by mountaintop-removal mining should focus on restoring the ionic compositions that naturally occur in this region

Upland Habitat Quality and Historic Landscape Composition Influence Genetic Variation of a Pond-Breeding Salamander

Understanding the temporal and spatial scale at which habitat alteration impacts populations is important for conservation and management. Amphibians have declined more than other vertebrates, and pond-breeding species are particularly susceptible to habitat loss and fragmentation because they have terrestrial and aquatic life stages. One approach to management of pond-breeding species is protection of core upland habitat surrounding the breeding pond. We used genetic variation as an indicator of population status in a common amphibian species, spotted salamanders (Ambystoma maculatum), to determine how amount of suitable upland habitat relates to population status in the greater Charlotte, North Carolina, USA metropolitan area. We developed candidate models to evaluate the relative influence of historical and contemporary forested habitat availability on population genetic variation at two spatial scales of upland area (164 m and 2000 m) at four time intervals over the past seven decades (1938, 1978, 1993, 2005). We found that historical land cover best predicted contemporary allelic richness. Inbreeding coefficient and observed heterozygosity were not effectively predicted by forest cover at either spatial or temporal scales. Allelic richness was best predicted at the smaller spatial scale in the 1993 time interval. Predicting and understanding how future landscape configuration affects genetic variation of common and rare species is imperative for the conservation of amphibian and other wildlife populations