Evaluation of habitat quality for selected wildlife species associated with island back channels

The islands and associated back channels on the Ohio River, USA, are believed to provide critical habitat features for several wildlife species. However, few studies have quantitatively evaluated habitat quality in these areas. Our main objective was to evaluate the habitat quality of back and main channel areas for several species using habitat suitability index (HSI) models. To test the effectiveness of these models, we attempted to relate HSI scores and the variables measured for each model with measures of relative abundance for the model species. The mean belted kingfisher (Ceryle alcyon) HSI was greater on the main than back channel. However, the model failed to predict kingfisher abundance. The mean reproduction component of the great blue heron (Ardea herodias) HSI, total common muskrat (Ondatra zibethicus) HSI, winter cover component of the snapping turtle (Chelydra serpentina) HSI, and brood-rearing component of the wood duck (Aix sponsa) HSI were all greater on the back than main channel, and were positively related with the relative abundance of each species. We found that island back channels provide characteristics not found elsewhere on the Ohio River and warrant conservation as important riparian wildlife habitat. The effectiveness of using HSI models to predict species abundance on the river was mixed. Modifications to several of the models are needed to improve their use on the Ohio River and, likely, other large rivers.

Effects of historic wildfire and prescribed fire on site occupancy of bats in Shenandoah National Park,Virginia,USA

Given the likelihood of regional extirpation of several once-common bat species in eastern North America from white-nose syndrome,it is critical that the impacts of forest management activities,such as prescribed fire,are known in order to minimize potentially additive negative effects on bat populations.Historic wildfires may offer a suitable surrogate to assess long-term burn impacts on bats for planning,implementing and assessing burn programs.To examine the effects of historic fire on bats,we sampled bat activities at 24 transect locations in burned and unburned forest stands in the central Appalachian Mountains of Shenandoah National Park(SNP),Virginia,USA.There was limited evidence of positive fire effects over time on hoary bats(Lasiurus cinereus Beauvois)and big brown bats(Eptesicus fuscus Beauvois)occupancy.Overall,there were few or mostly equivocal relationships of bat occupancy relative to burn conditions or time since fire in SNP across species using a false-positive occupancy approach.Our results suggest that fire does not strongly affect bat site occupancy short-or long-term in the central Appalachians.

Fuel and vegetation changes in southwestern, unburned portions of Great Smoky Mountains National Park, USA, 2003-2019

Overstory basal area,ericaceous shrub cover(Kalmia latifolia L.and Rhododendron maximum L.),and fuels(i.e.,woody fuel loads and depths and O Horizon thickness) were assessed within Great Smoky Mountains National Park,USA,in 2003-2004.Due to recent wildfire activity within the southern Appalachian Mountain region(including Great Smoky Mountains National Park),the potential spread and expansion of ericaceous shrubs,and the impacts of the hemlock woolly adelgid(Adelges tsugae Annand) on eastern hemlock(Tsuga canadensis(L.) Carrière),these same ecosystem components were again assessed in 2019.Elevation and moisture regime(xeric,intermediate,and mesic) were included in this assessment as potential influential factors.An evaluation of repeated measurements from 40 plots suggested that O Horizon thickness did not change significantly over the 16-year period,but increased as elevation increased,and moisture regime(xeric O Horizon thickness> mesic O Horizon thickness) was a significant,related factor.The sum of 1-,10-,and 100-h fuel loads(fuels less <7.6 cm diameter)increased,whereas woody fuel depth decreased over the16-year period.No significant changes in 1000-h fuel lo ads(>7.6 cm diameter),total woody fuel loads,ericaceous shrub cover,total basal area,or live T.canadensis basal area were observed.Live T.canadensis basal area decreased with increasing elevation.Dead,standing T.canadensis basal area increased from 2003-2019,and that increase was most pronounced as elevation increased on xeric and intermediate sites.Overall,we found that:1.hypothesized increases in total woody fuel loads and ericaceous shrub cover were not present;and 2.elevation and moisture regime were most related to observed changes in vegetation and fuel condition.

Comparison of Geographically Weighted Regression of Benthic Substrate Modeling Accuracy on Large and Small Wadeable Streams

Aquatic habitat assessments encompass large and small wadeable streams which vary from many meters wide to ephemeral. Differences in stream sizes within or across watersheds, however, may lead to incompatibility of data at varying spatial scales. Specifically, issues caused by moving between scales on large and small streams are not typically addressed by many forms of statistical analysis, making the comparison of large (>30 m wetted width) and small stream (<10 m wetted width) habitat assessments difficult. Geographically weighted regression (GWR) may provide avenues for efficiency and needed insight into stream habitat data by addressing issues caused by moving between scales. This study examined the ability of GWR to consistently model stream substrate on both large and small wadeable streams at an equivalent resolution. We performed GWR on two groups of 60 randomly selected substrate patches from large and small streams and used depth measurements to model substrate. Our large and small stream substrate models responded equally well to GWR. Results showed no statistically significant difference between GWR R2 values of large and small stream streams. Results also provided a much needed method for comparison of large and small wadeable streams. Our results have merit for aquatic resource managers, because they demonstrate ability to spatially model and compare substrate on large and small streams. Using depth to guide substrate modeling by geographically weighted regression has a variety of applications which may help manage, monitor stream health, and interpret substrate change over time.

Accuracy of Stream Habitat Interpolations Across Spatial Scales

Stream habitat data are often collected across spatial scales because relationships among habitat, species occurrence, and management plans are linked at multiple spatial scales. Unfortunately, scale is often a factor limiting insight gained from spatial analysis of stream habitat data. Considerable cost is often expended to collect data at several spatial scales to provide accurate evaluation of spatial relationships in streams. To address utility of single scale set of stream habitat data used at varying scales, we examined the influence that data scaling had on accuracy of natural neighbor predictions of depth, flow, and benthic substrate. To achieve this goal, we measured two streams at gridded resolution of 0.33 × 0.33 meter cell size over a combined area of 934 m2 to create a baseline for natural neighbor interpolated maps at 12 incremental scales ranging from a raster cell size of 0.11 m2 to 16 m2. Analysis of predictive maps showed a logarithmic linear decay pattern in RMSE values in interpolation accuracy for variables as resolution of data used to interpolate study areas became coarser. Proportional accuracy of interpolated models (r2) decreased, but it was maintained up to 78% as interpolation scale moved from 0.11 m2 to 16 m2. Results indicated that accuracy retention was suitable for assessment and management purposes at various scales different from the data collection scale. Our study is relevant to spatial modeling, fish habitat assessment, and stream habitat management because it highlights the potential of using a single dataset to fulfill analysis needs rather than investing considerable cost to develop several scaled

Sedimentation in Mountain Streams: A Review of Methods of Measurement

The goal of this review paper is to provide a list of methods and devices used to measure sediment accumulation in wadeable streams dominated by cobble and gravel substrate. Quantitative measures of stream sedimentation are useful to monitor and study anthropogenic impacts on stream biota, and stream sedimentation is measurable with multiple sampling methods. Evaluation of sedimentation can be made by measuring the concentration of suspended sediment, or turbidity, and by determining the amount of deposited sediment, or sedimentation on the streambed. Measurements of deposited sediments are more time consuming and labor intensive than measurements of suspended sediments. Traditional techniques for characterizing sediment composition in streams include core sampling, the shovel method, visual estimation along transects, and sediment traps. This paper provides a comprehensive review of methodology, devices that can be used, and techniques for processing and analyzing samples collected to aid researchers in choosing study design and equipment.

Predicting intensity of white-tailed deer herbivory in the Central Appalachian Mountains

In eastern North America, white-tailed deer(Odocoileus virginianus) can have profound influences on forest biodiversity and forest successional processes.Moderate to high deer populations in the central Appalachians have resulted in lower forest biodiversity.Legacy effects in some areas persist even following deer population reductions or declines. This has prompted managers to consider deer population management goals in light of policies designed to support conservation of biodiversity and forest regeneration while continuing to support ample recreational hunting opportunities. However,despite known relationships between herbivory intensity and biodiversity impact, little information exists on the predictability of herbivory intensity across the varied and spatially diverse habitat conditions of the central Appalachians. We examined the predictability of browsing rates across central Appalachian landscapes at four environmental scales: vegetative community characteristics, physical environment, habitat configuration, and local human and deer population demographics. In an information-theoretic approach, we found that a model fitting the number of stems browsed relative to local vegetation characteristics received most(62%) of the overall support of all tested models assessing herbivory impact. Our data suggest that deer herbivory responded most predictably to differences in vegetation quantity and type. No other spatial factors or demographic factors consistently affected browsing intensity. Because herbivory, vegetation communities, and productivity vary spatially, we suggest that effective broad-scale herbivory impact assessment should include spatially-balanced vegetation monitoring that accounts for regional differences in deer forage preference.Effective monitoring is necessary to avoid biodiversity impacts and deleterious changes in vegetation community composition that are difficult to reverse and/or may not be detected using traditional deer-density based management goals.

Responses of early-successional songbirds to a two-stage shelterwood harvest for oak forest regeneration

Background: The early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ultimately resulting in their displacement. These early stages following forest disturbance, which are declining throughout the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives.Methods: We investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the midCumberland Plateau in the eastern United States.Results: Canopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren(Thryothorus ludovicianus), Eastern Towhee(Pipilo erythrophthalmus), Indigo Bunting(Passerina cyanea), and Yellowbreasted Chat(Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch(Spinus tristis), Prairie Warbler(Setophaga discolor), and White-eyed Vireo(Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012.Conclusion: The two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term(> 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method.

淡水珍珠贝寿命差异的研究:检验动物长寿机制的样板种类

世界上已知有十多种动物的最大寿命(Amax)可超过100年,淡水珍珠贝(Margaritifera margaritifera)即是其中的一种。这种动物寿命较长者可达到100～200年,寿命的长短与其生活地的环境条件及所处纬度有关。淡水珍珠贝南方种群与北极地区种群相比,其寿命差异可以达3～7倍。一些南方种群的最大寿命为28～40年,而在北极地区则可达到114～190年。用进化和生态学的观点来看,北极地区珍珠贝长寿的原因可能是因为这些地区性种群已适应了当地恶劣、多变的气候及水文条件,寒冷气候条件下较低的代谢率及生长过程中较低的能量消耗均对长寿产生了积极的影响。为使损坏的贝壳或机体组织得以修复或自愈,这类物种通常能很快地将其代谢率水平增加至130倍。通过对这类物种进行生理学的研究,相信在理解长寿和延迟衰老的机理方面能有极大的收获。