Third-order Scale Research Articles

Active grid turbulence anomalies through the lens of physics informed neural networks

Active grids operated with random protocols are a standard way to generate large Reynolds number turbulence in wind and water tunnels. But anomalies in the decay and third-order scaling of active-grid turbulence have been reported. We combine Laser Doppler Velocimetry and hot-wire anemometry measurements in a wind tunnel, with machine learning techniques and numerical simulations, to gain further understanding on the reasons behind these anomalies. Numerical simulations that incorporate the statistical anomalies observed in the experimental velocity field near the active grid can reproduce the experimental anomalies observed later in the decay. The results indicate that anomalies in experiments near the active grid introduce correlations in the flow that can persist for long times.

Habitat Selection of Female Rio Grande Wild Turkey Influenced by Vegetation and Anthropogenic Structures

The Rio Grande wild turkey (Meleagris gallopavo intermedia) is a popular game species throughout the southcentral United States. It has experienced recent population declines in some areas of its distribution, though the cause is not clear. To better understand Rio Grande wild turkey (hereafter, turkey) ecology and inform management, we attached Global Positioning System transmitters to 34 females in 2016 and 2017. We evaluated habitat selection at both the second-order (landscape) and third-order (home range) scale for the breeding season and second-order selection for the nonbreeding season. Our resource selection function (RSF) models evaluated vegetation, management, and anthropogenic development including oil and gas infrastructure and roads. We found that turkey space use was strongly associated with tall woody cover at both the landscape and home range scale during breeding season and at the landscape scale during nonbreeding season. Additionally, turkey space use was negatively related to the density of oil/gas wells at both scales during the breeding season and at the landscape scale during the nonbreeding season. Turkeys also selected areas close to roads at the landscape scale but avoided high traffic roads within their home ranges during the breeding season. Turkey also chose areas that were >24 mo post fire and close to water sources during the breeding season at both scales. Although turkeys exhibited consistent habitat selection patterns throughout the year relative to trees and oil and gas, our results suggest that their habitat requirements in western Oklahoma are seasonally variable. Management for the Rio Grande subspecies of turkey should maintain tree cover that provides roosting and loafing cover, as well as consider the potential negative impacts of oil and gas infrastructure when locating future energy development.

Memory feedback signals in nonlinear coupled pitch-roll ship motions under narrow-band stochastic excitations

Initiating from the complexity of ship sailing environment and the nonlinear coupling hysteresis effect of its motion, we focus on the memory feedback shake-reducing strategy turning from the delay generally considered to exhibit undesired effects, and introduce it into the nonlinear coupled pitch-roll ship motions under loads incorporating stochastic disturbances to control the ship shaking and optimize the frequency band distribution of the stable navigation associated with the saturation. This paper then reports the deterministic equilibrium solutions of the roll and pitch response via the perturbation analysis of the third-order scale and successively explains the stability closely related to the saturation and bifurcations. Instead of just formula deduction, visually depict the distinction of equilibrium points and the determination conditions, and the effective shake-reducing frequency band coupled with the drift modulated by the memory feedback signals, and then integrate the moment method and stochastic Itô law to compute the steady-state moment and the mean square scale checked by numerical simulations. Set basic samples of the equation parameters for dual scenarios, and then track time histories of ship rolling and pitching as well as the marginal and joint probability evolutions to illustrate the resonance behavior and modes transition with the energy penetration in complementary ways. The results of our investigation present a new insight into the stability schemes of ship sailing issues.

Analytic gradients for local density fitting Hartree-Fock and Kohn-Sham methods.

We present analytic gradients for local density fitting Hartree-Fock (HF) and hybrid Kohn-Sham (KS) density functional methods. Due to the non-variational nature of the local fitting algorithm, the method of Lagrange multipliers is used to avoid the solution of the coupled perturbed HF and KS equations. We propose efficient algorithms for the solution of the arising Z-vector equations and the gradient calculation that preserve the third-order scaling and low memory requirement of the original local fitting algorithm. In order to demonstrate the speed and accuracy of our implementation, gradient calculations and geometry optimizations are presented for various molecular systems. Our results show that significant speedups can be achieved compared to conventional density fitting calculations without sacrificing accuracy.

Unique Land Cover Classification to Assess Day-Roost Habitat Selection of Northern Long-Eared Bats on the Coastal Plain of North Carolina, USA

Reproductively successful and over-wintering populations of the endangered northern long-eared bat (Myotis septentrionalis) have recently been discovered on the Coastal Plain of North Carolina. Empirical data on resource selection within the region is limited, likely hindering management of these coastal forests. Our objectives were to determine roosting home range size, selection of day-roost tree species, second- and third-order roosting habitat selection, and to quantify the overall availability of resources in the surrounding landscape. We found core and peripheral roosting home range estimates were large, yet similar to observations from other areas of contiguous forests. Prior to juvenile volancy, female northern long-eared bats appear to select red maple (Acer rubrum), water ash (Fraxinus caroliniana), and loblolly pine (Pinus taeda) as day-roosts, but then use sweetgum (Liquidambar styraciflua), swamp bay (Persea palustris), and water tupelo (Nyssa aquatica) after juvenile volancy. At the second-order spatial scale, roosting home ranges were associated with woody wetlands farther from anthropogenic development and open water. However, within the third-order scale, northern long-eared bats were associated with undeveloped woody wetlands and upland forests, areas containing shorter trees and occurring proximal to open water. Peripheral and core areas were predicted to comprise approximately 20% of the local landscape. Our results show that complex and large tracts of woody wetlands juxtaposed with upland forests in this part of the Coastal Plain may be important for northern long-eared bats locally, results largely consistent with species management efforts in eastern North America.

Scale, origin, and predictability of reservoir heterogeneities in shallow-marine carbonate sequences: A case from Cretaceous of Zagros, Iran

This study presents an integrated reservoir heterogeneity analysis of an Iranian carbonate oil reservoir (Sarvak Formation) in the Zagros region. Both static and dynamic aspects of reservoir heterogeneities are considered by integration of routine–special core data and geological attributes (i.e., depositional facies and textures, diagenetic alterations, pore types, and sequence stratigraphic positions). Core porosity and permeability, mercury injection capillary pressure, and scanning electron microscopy data are used along with the results of petrographic studies to define petrographic rock types, pore types, hydraulic flow units, and reservoir to non-reservoir (baffle or barrier) zones in the studied reservoir. Spatial facies distribution (facies variability) and development of disconformable surfaces (sequence boundaries) controlled the large-scale reservoir heterogeneities. On the other hand, variations in microscopic characteristics of depositional facies (i.e., textures and structures) and diagenetic features (e.g., intensity of dissolution, cementation and compaction) formed the small-scale reservoir heterogeneities. The best productive zones of this reservoir are meteorically-dissolved reef-talus and shoal facies, accumulated within the regressive systems tracts of third-order sequences. Intensively compacted and cemented facies formed the effective vertical barrier/baffle zones in this reservoir, especially within the transgressive systems tracts and around the maximum flooding surfaces. Results of this study revealed that the stratigraphic modified Lorenz plot (SMLP) is a useful tool for the discrimination of large-scale reservoir heterogeneities, while hydraulic flow units and Winland rock typing approaches are applicable for the identification of small-scale heterogeneities. This study indicated that the large-scale heterogeneities of carbonate reservoirs are predictable in a sequence stratigraphic framework, especially in the third-order scale. Such a heterogeneity model calibrated in the sequence stratigraphic framework provides a reliable basis for reservoir modeling of heterogeneous carbonate reservoirs in the field-to regional scales.

The Yaglom Scaling of the Third-order Structure Functions in the Inner Heliosphere Observed by Helios 1 and 2

Abstract The third-order scaling law, Yaglom law, of Elsässer fluctuations in the solar wind is believed to reflect the inertial range energy cascade of the MHD turbulence and provides an approach to evaluate the cascade rate. However, the occurrence ratio with the Yaglom scaling law, the fraction of the intervals where the Yaglom linear scaling is observed, is reported to be low (0.05–0.30) in the high-latitude solar wind observed by the Ulysses spacecraft. Whether the occurrence ratio could be higher in other conditions remains unknown. Here, we analyze the occurrence of the third-order scaling in the inner heliosphere with the first 100 days of observation of the Helios 1 and Helios 2 spacecraft. We investigate 162 intervals in the leading edges and 323 intervals in the trailing edges of the high-speed streams, respectively. All of these intervals have a time duration of 9 hr. We find that in the inner heliosphere the occurrence ratio is relatively high in the leading edges (0.58) and moderate in the trailing edges (0.45). Among the data intervals with the Yaglom scaling in the leading edges, 94.7% of intervals give positive rates, while in the trailing edges 78.6% give negative rates. The variations of the occurrence ratio with various turbulence parameters are shown. The cascade rate is found to be higher than the proton heating rate calculated from the data, which have third-order scaling. These new results raise several questions related to the nature and origin of the third-order scaling law and may initiate new studies on solar wind turbulence.

Building value with packaging: Development and validation of a measurement scale

In the absence of studies that include holistically all the current functionalities of packaging, this research develops and validates at confirmatory level a third-order scale for measuring the functional value of packaging. The measure accounts for protection, convenience, portability & storage, information, branding, engagement, sustainability and economy and considers active and intelligent functions. The psychometric properties of the scale are analysed in a total of 5 studies. Results indicates that protection, sustainability and information are the most relevant functions. This scale amounts to a useful tool that can serve as a framework for managers in numerous sectors.

Sequence-stratigraphic study of Cuyo Group in the Agua del Cajón Block, Neuquén Basin, Argentina

Agua del Cajón Block is located towards the north-east flank of the Huincul High deformation belt. The Cuyo Group, one of the main hydrocarbon targets of the block, was analyzed under the sequential-stratigraphic seismic methodology, for the purpose of establishing a genetic depositional framework that guides the development of new prospective models in the area. Ages and paleoenvironmental indicators calibration were obtained from biostratigraphic sampling. In Agua del Cajón Block, the Cuyo Group was interpreted as a second-order mesosequence, composed of eight third-order seismic sequences. Seismic-stratigraphy was integrated with the structural framework of the block, allowing an interpretation of the tectono-stratigraphic evolution of the analyzed interval. It is concluded that the development of the Cuyo Group manifests eustatic control at a second-order mesosequence scale, while at the third-order scale the sequence arrangement was modified by local tectonics.

Spatial ecology of river otters in a human-modified landscape

AbstractRiver otter populations have expanded across much of their historical range, including in Illinois where they were reintroduced from 1994 to 1997. These expanding populations are recolonizing a wide range of landscapes with different levels of human modification, which could influence how river otters use space in relation to habitat characteristics and each other. Our objectives were to quantify 1) home ranges and core areas, 2) sociality, and 3) habitat selection across all available habitats and within home ranges (second- and third-order selection, respectively) of 22 radiomarked river otters (Lontra canadensis) in southern Illinois during 2014–2016. Our study area contained a diverse mix of forest, agriculture, aquatic and wetland habitats, and a range of urban development intensity. We examined sociality using the frequency at which individuals were located < 25 m from a conspecific and compared home-range overlap among individuals based on sex. Habitat selection at the second and third order was analyzed using an eigen-analysis of selection ratios based on landcover categories. Similar to other studies, male river otters had > 2-fold larger home ranges and core areas than females in southern Illinois. Several lines of evidence indicated males were more social than females. Males were located close to a conspecific more frequently than were females, and overlap of home ranges and core areas among males was greater than it was among females or between sexes. As observed in other landscapes, river otters strongly selected herbaceous and wooded wetlands at both second- and third-order scales. River otters selected terrestrial cover types with vegetative cover potentially due to shelter or prey availability. Forests were selected over crop fields at the third-order scale, which was consistent with studies using sign surveys. River otters in our study had home ranges containing 0–40% developed land cover, but we found no evidence that otters living in more developed areas used their home ranges more selectively. River otters in this landscape were plastic in regard to social behavior and habitat selection, highlighting their generalist nature and providing insight into their ability to successfully recolonize areas of the Midwest with sufficient vegetative cover and aquatic habitat, among other factors.

Habitat selection by American beaver at multiple spatial scales

BackgroundSemiaquatic mammals require both aquatic and terrestrial habitats, particularly interfaces between the two habitats. As ecosystem engineers, American beaver (Castor canadensis) consume and fell a great amount of deciduous trees. We tested the prediction that open water and amounts of food resources, including hardwood forests (i.e., deciduous trees as the dominant form of vegetation), herbaceous and woody wetlands, and shrubs, would influence the second-order habitat selection (i.e., placing home ranges on the landscape) by American beaver, whereas the third-order habitat selection of American beaver would be associated with woody wetland and shrub edges. We investigated hierarchical habitat selection by American beaver using location data from very high frequency telemetry. Dirichlet-multinomial models were used to determine the second-order habitat selection at landscape scales. Bayesian spatial resource selection function was used to assess the third-order habitat selection within home ranges.ResultsSecond-order habitat selection by American beaver was associated with herbaceous wetland, shrubs, hardwood forest, grassland, and woody wetland more than open water bodies at landscape scales. At the third-order scale, American beaver selected herbaceous wetlands as well as the edges of shrubs and woody wetland within established home ranges.ConclusionsSpatial distributions of food resources affected both the second- and third-order habitat selection by American beaver. Herbaceous wetlands were more important habitat components than water bodies in the second- and third-order habitat selection by American beaver. Dirichlet-multinomial distribution models for the second-order habitat selection and Bayesian spatial resource selection functions for the third-order habitat selection do not need pseudo-absence locations, providing alternative approaches to the presence–absence methods for habitat selection by animals.

Measuring customer experience in physical retail environments

PurposeIn a world where customer empowerment is continuously increasing and changing the service landscape, retailers must provide memorable shopping experiences to retain and attract new customers. When customers decide to go shopping in physical stores, they expect to enjoy their visit, experiencing cognitive, affective, social, and physical responses evoked by in-store stimuli. The purpose of this paper is to propose and validate a scale to measure in-store customer experience (ISCX).Design/methodology/approachThis study’s theoretical review of customer experience (CX) demonstrates that a formative model provides the best structure for measuring the construct ISCX. Furthermore, the study follows the guidelines for rigorous construction of a formative scale, which include three main stages: generation of items, scale purification, and assessment of scale validity and reliability.FindingsThe results provide evidence that a formative third-order scale with a reflective second-order dimension (social experience) and three reflective first-order dimensions (cognitive, affective, and physical experience) has satisfactory psychometric properties. The findings also provide useful information on the effect of the ISCX scale on key performance variables such as satisfaction and loyalty to the store.Originality/valueThe ISCX scale proposed constitutes a useful multi-concept diagnostic tool for use by retailers to create fully experiential shopping environments with differential value for the customer. By providing a complete, robust, precise measure of CX in a retail environment, the scale gives researchers a structured way to examine the causes and consequences of CX in retail.

Habitat selection by a generalist mesopredator near its historical range boundary

The Virginia opossum (Didelphis virginiana Kerr, 1792) has expanded its geographic range northward since European settlement, which has been attributed to its ability to exploit anthropogenic resources. To examine the utility of anthropogenic resources to this species, we monitored 61 opossums from 2009 to 2010 with very high frequency (VHF) telemetry in a fragmented agricultural ecosystem in northern Indiana, USA, at the periphery of the opossum’s historical distribution. We examined the influence of anthropogenic (agricultural areas, developed land, roads), disturbed (corridor, forest edge, grassland, water), and native (forest, shrub land) habitats on habitat selection at the second- and third-order scales across three seasons. At the second-order scale, areas proximate to agricultural fields and developed land were selected in the breeding and postbreeding seasons, respectively. Areas proximate to roads were selected at both spatial scales during all seasons except winter at the third-order scale. Areas near forest with high forest-edge density were selected throughout the year at both spatial scales, but confidence intervals for forest during the postbreeding season marginally overlapped zero (third-order scale). Although anthropogenic habitats provide novel resources for opossums, forest and forest edge remain essential components to populations near their historical distributional limit in agricultural ecosystems.

High-resolution sequence stratigraphy and continental environmental evolution: An example from east-central Argentina

The aims of this contribution is to establish a high-resolution sequence stratigraphic scheme for the continental deposits that constitute the Punta San Andrés Alloformation (Plio-Pleistocene) in east-central Argentina, to analyze the basin fill evolution and to identify and assess the role that extrinsic factors such as climate and sea-level oscillations played during evolution of the unit.For the high-resolution sequence stratigraphical study of the Punta San Andrés Alloformation, high- and low-accommodation system tracts were defined mainly on the basis of the architectural elements present in the succession, also taking into account the relative degree of channel and floodplain deposits. Discontinuities and the nature of depositional systems generated during variations in accommodation helped identify two fourth-order high-accommodation system tracts and two fourth-order low-accommodation system tracts. At a third-order scale, the Punta San Andrés Alloformation may be interpreted as the progradation of continental depositional systems, characterized by a braided system in the proximal areas, and a low-sinuosity, single-channel system in the distal areas, defined by a high rate of sediment supply and discharge peaks which periodically flooded the plains and generated high aggradation rates during the late Pliocene and lower Pleistocene.

Neoarchaean tectonic history of the Witwatersrand Basin and Ventersdorp Supergroup: New constraints from high-resolution 3D seismic reflection data

First-order scale structures in the West Wits Line and West Rand goldfields of the Witwatersrand Basin (South Africa) were mapped using the high-resolution 3D reflection seismic method. Structural models constrain the magnitude of displacement of thrusts and faults, the gross structural architecture and Neoarchaean tectonic evolution of the West Rand and Bank fault zones, which offset the gold-bearing reefs of the basin.The merging of several 3D seismic surveys made clear the gross strato-structural architecture of the goldfields; a macroscopic fold-thrust belt is crosscut by a macroscopic extensional fault array. These are dissected, eroded and overlain by the Transvaal Supergroup above an angular unconformity.The seismic sections confirm that the West Rand Group (ca. 2985–2902Ma) is unconformably overlain by the Central Rand Group (ca. 2902–2849Ma), with tilting of the West Rand Group syn- to post-erosion at ca. 2.9Ga. The seismic sections also confirm that an unconformable relationship exists between the Central Rand Group and the auriferous Ventersdorp Contact Reef (VCR), with an easterly-verging fold-thrust belt being initiated concomitant to deposition of the VCR at approximately 2.72Ga. Fold-thrust formation included development of the (1) newly identified first-order scale Libanon Anticline, (2) Tandeka and Jabulani thrusts which displace the West Rand Group, and (3) parasite folds.The fold-thrust belt is crosscut by a macroscopic extensional fault array (or rift-like system of faults) which incepted towards the end of extrusion of the Ventersdorp lavas, and certainly during deposition of the Platberg Group (2709–2643Ma) when a mantle plume may have heated the lithosphere. The West Rand and Bank fault zones formed at this time and include (1) the West Rand and Bank faults which are scissors faults; (2) second and third-order scale normal faults in the immediate footwall and hanging wall of the faults; (3) drag synclines, and (4) rollover anticlines.

New signal scaling strategies for return phase training in motion-base spaceflight simulator

Signal scaling is an essential step in spaceflight simulation. Thus far, the third-order polynomial scaling method has been widely used for signal scaling; however, in this method, parameter tuning is complicated and may induce perceptible distortion during large-range monotonic signal scaling. In the simulation of spacecraft return, specifically, that of re-entry, acceleration and angular velocity signals may vary considerably over short time periods. Motion perception is important for training astronauts in this phase. In this study, two strategies are proposed to solve these problems using the ‘scaling scope’ parameter. The first strategy is based on the Hermite interpolation polynomial, and the other is based on third-order polynomial scaling. Two methods were developed which make use of the stable region of third-order polynomial scaling. The first method maximizes the stable region to prevent signal distortion, and the other restricts the scaling scope in the stable region. Based on the dynamic characteristics of spacecraft in the return phase, the signal scaling strategies proposed in this study are simulated for trainees’ perception in a motion-base simulator. Simulations were implemented by utilizing the full curves of spacecraft return phase for the first time, and results show that these methods are more advantageous for parameter tuning and can eliminate signal distortion for all input signals. While these methods have a shortcoming in that the trigger velocity (onset cue) is slowed down, this shortcoming is eliminated by employing the moving cueing algorithm. Both the strategies proposed in this article show good performance and can be applied potentially to the motion simulation of the spacecraft return phase.

Identifying indirect habitat loss and avoidance of human infrastructure by northern mountain woodland caribou

Understanding the impact of indirect habitat loss resulting from avoidance of human infrastructure is an important conservation priority. We evaluated resource selection for 10 global positioning system collared northern mountain woodland caribou ( Rangifer tarandus caribou) in British Columbia, Canada, with seasonal resource selection functions (RSF) developed at the second-order (landscape) and third-order (within home range) scales. To estimate how much habitat was lost due to avoidance, we estimated the zone of influence (ZOI) around multiple developments and modeled realized and potential habitat. Potential habitat was approximated by removing the ZOI from RSF models. By calculating the spatial difference between potential and realized habitat we estimated the amount of indirect habitat loss. Caribou displayed hierarchical avoidance of development, with the greatest avoidance occurring at the second-order. During both seasons caribou avoided high-use roads by 2 km and low-use roads by 1 km. In winter, caribou avoided town by 9 km compared to 3 km in summer. However, in summer caribou avoided mines by 2 km and cabins and camps by 1.5 km, while in winter when human activity was low, avoidance of these features was minor. As a result of avoidance of the cumulative ZOI, approximately 8% and 2% of high quality habitat was lost in the study area in winter and summer, respectively. Our study provides an approach to identify the extent and quality of habitat influenced by indirect avoidance. Conservation efforts should prioritize protecting areas of high quality habitat degraded by avoidance in the vicinity of human development.

Constrained surface interpolation by means of a genetic algorithm

We propose an evolutionary technique (a genetic algorithm) to solve heavily constrained optimization problems defined on interpolating tensor product surfaces by adjusting the parameter values associated with the data points to be interpolated. Throughout our study we assume that the functional, which operates on these types of interpolating surfaces, is described by a surface integral and fulfills the following conditions: it is not necessarily a smooth functional (i.e., it may have vanishing gradient vectors), it is bounded (i.e., the optimization algorithm can converge in a finite number of steps), it is invariant under parametrization, rigid body transformation and uniform scaling (i.e., different surface parametrization at different scales should generate the same optimized shape). We have successfully tested the proposed algorithm for functionals that involve: minimal surface area, minimal Willmore, umbilic deviation and total curvature energies, minimal third-order scale invariant weighted Mehlum–Tarrou energies, and isoperimetric like problems. In general, our algorithm can be used in the case of any kind of not necessarily smooth surface fairing functionals. The run-time and memory complexities of the suggested algorithm are reasonable. Moreover, the algorithm is independent of the type of tensor product surface.

Palynofacies and sea-level changes in the Upper Cretaceous of the Vocontian Basin, southeast France

Upper Cretaceous platform carbonates of the Vocontian Basin (southeastern France) have been investigated in a cross-section from the proximal deposits exposed in the lower Rhône Valley to the distal part of the basin in the Southern Subalpine Ranges north of Nice. The stratigraphic interval studied in detail spans the uppermost Turonian and Coniacian. Palynofacies patterns were used to detect eustatic signals at a third-order scale and are the tool for correlation of proximal and distal platform deposits. The organic constituents observed in the studied samples have been grouped into a continental fraction, including higher plant debris (phytoclasts) and sporomorphs, and a marine fraction with dinoflagellate cysts, acritarchs, prasinophytes, and foraminiferal test linings. The main factors influencing the stratigraphic and spatial distribution of land-derived, allochthonous, and marine, relatively autochthonous, organic particles are the proximity of land, the organic productivity, the degree of biodegradation and the hydrodynamic conditions of the depositional system. Palynofacies parameters used for the sequence stratigraphic interpretation are: (1) the ratio of continental to marine constituents (CONT/MAR ratio); (2) the ratio of opaque to translucent phytoclasts (OP/TR ratio); (3) the phytoclast particle size and shape; and (4) the relative proportion and species diversity of marine plankton. Ternary diagrams illustrating significant proximality changes were used to decipher transgressive-regressive trends within the succession. High amounts of translucent phytoclasts and decreasing values of the CONT/MAR ratio occur during the phase of relative sea-level rise in the upper Turonian. The stratigraphic interval of maximum flooding around the Turonian/Coniacian boundary is marked by the highest abundance and species diversity of dinoflagellate cysts, and by high percentages of opaque, equidimensional particles within the phytoclast group. The OP/TR ratio is still high within the lower Coniacian representing the early highstand deposits, whereas the relative abundance of marine constituents is again decreasing. Sedimentary organic matter of the upper Coniacian is dominated by large, blade-shaped, mainly opaque phytoclasts, which are a characteristic palynofacies signature of late highstand deposits. The present study demonstrates the high potential of palynofacies analysis in high-resolution stratigraphy and correlation of sedimentary series of shallow epeiric seas.

Grizzly bears and forestry: I. Selection of clearcuts by grizzly bears in west-central Alberta, Canada

We examined if clearcuts were selected as habitats by grizzly bears ( Ursus arctos L.) in west-central Alberta during three seasons: hypophagia, early hyperphagia, and late hyperphagia. Our objectives were to describe seasonal habitat selection of clearcuts using resource selection functions at two scales. At the first scale, we assessed patch or third-order selection by comparing use (radiotelemetry) with study area-wide random locations and a dummy variable identifying whether locations occurred within or outside of clear-cut boundaries. At the second scale, we assessed within-patch or fourth-order selection by comparing locations (use and random) found within clearcuts and environmental covariates of terrain, silviculture, and landscape metrics. Finally, we examined diurnal versus crepuscular/nocturnal use of clearcuts by comparing the two with an expected 50:50 ratio. At the third-order scale, grizzly bears used clearcuts with respect to their availability for hypophagia and late hyperphagia, while selecting clearcuts more than expected during early hyperphagia. Fourth-order habitat selection revealed that landscape metrics, silviculture, and terrain were important predictors of grizzly bear use during hypophagia and late hyperphagia, while terrain appeared to be the most important predictor during early hyperphagia. Overall, grizzly bears avoided clear-cut interiors and preferred clearcuts with higher perimeter-to-edge ratios. Clearcuts were significantly more likely to be used during crepuscular/nocturnal periods. Intermediate-aged (∼30 years old) clearcuts were selected during hypophagia, whereas recent and old clearcuts were selected during late hyperphagia. Bears tended to avoid clearcuts with Donaren mound preparation, while selecting clearcuts with Bracke or shark-fin barrel dragging. These results suggest that landscape metrics, site preparation history, terrain, and season were important factors determining the use of clearcuts by grizzly bears. Future forest planning should strive to maximize habitat quality by: (1) increasing perimeter-to-edge ratio for clear-cut shapes; (2) using low impact and/or positively associated site preparation treatments like Bracke and shark-fin barrel dragging; and (3) limiting human access to areas predicted as high-quality habitat.