Physical Site Characteristics Research Articles

Potential Biases in Mixed-Effects Ground-Motion Models and Variance Components Due to Uncertainty in Random Effects

ABSTRACT Empirical ground-motion models are typically estimated via mixed-effects regression, to account for correlation between records from the same event or from the same site or station. Estimated values of the random effects are often used in further analyses, for example, to develop additional submodels or to investigate physical characteristics of individual events or sites. Such analyses often do not account for uncertainty in the random effects. Using simulations, we show that neglecting these uncertainties can lead to a variety of biases, such as underestimation of variances or biased scaling with predictor variables. We demonstrate that these biases can often be overcome by estimating more complex (e.g., Bayesian) models on the total residuals of a mixed-effects regression.

Habitat selection by lake trout at reefs near Drummond Island, Lake Huron: An evaluation of physical characteristics used for spawning

Continued dependence on stocking of hatchery-reared lake trout, Salvelinus namaycush, in the Laurentian Great Lakes indicates recruitment bottlenecks still exist between spawning and the juvenile life stage (age-1). Possible impediments include poor habitat quality and an inability of hatchery-origin adults to select substrates that support successful incubation. Understanding of characteristics of suitable lake trout spawning habitat is limited but has centered on the cobble-contour framework, which identifies sloped reefs with cobble substrate and deep interstices to entrain eggs as spawning habitat. A novel sampling design based on acoustic-telemetry detections was used to evaluate relative importance of cobble-contour habitat characteristics (substrate size, homogeneity, interstitial depth, and slope) for predicting egg presence on two spawning reefs in northern Lake Huron. Fixed effect logistic regression models were used to relate egg presence to all possible combinations of measured physical characteristics. Physical characteristics of sites with naturally spawned eggs present varied, and no single best model predicted egg presence. Model selection and multi-model inference revealed slope to be the only informative predictor. Substrate size, homogeneity, and interstitial depth were not important. Embryo survival-to-hatch was also compared among sampling sites using in situ habitat bioassays seeded with hatchery fertilized embryos. No difference in embryo survival was observed between sites where naturally spawned eggs were present vs. absent. Over half of sites evaluated exceeded 75% survival. Naturally spawned eggs were observed at 25 of 57 sites. We suspect other characteristics such as interstitial flow could be helpful for predicting selection of lake trout spawning habitats.

Evaluating translocation success of wild eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) in Blue Ridge Ecoregion streams using pre- and post-translocation home range sizes and movement metrics.

Translocations of freshwater species have become a widespread conservation strategy to mitigate the impacts of habitat fragmentation, yet they are not often rigorously monitored using animal movement data to determine their success. We demonstrate the value of monitoring pre- and post-translocation movements and home-range sizes of a fully-aquatic, benthic stream salamander, the eastern hellbender (Cryptobranchus a. alleganiensis) to determine translocation success. We studied the home range sizes, movements, and habitat use of individuals (n = 27) in two self-sustaining populations (S1 & S2) for one year, and then subsequently collected similar data from a subset of these individuals (n = 17) that were translocated into two nearby streams (T1 & T2) with dam-isolated, declining populations in the Blue Ridge Ecoregion of Tennessee. We collected 1,571 location data points (869 pre-translocation and 715 post-translocation) from four study sites, and evaluated effects of mass, sex, and pre-translocation home range size/sedentariness, as well as habitat covariates on home range size and movements. Hellbender home range sizes increased from pre-translocation estimates at both sites, but response depended primarily on physical characteristics of release sites. Home range and fine-scale movement metrics indicated that hellbenders translocated from S1 to T1 settled in more quickly, had greater site fidelity, and smaller home ranges than hellbenders translocated from S2 to T2. Hellbender movements were influenced by cover rock size and density rather than individual characteristics. Study-long survival rates of translocated hellbenders increased from S1 to T1 (80% to 100%) and decreased from S2 to T2 (76% to 33%). Monitoring pre- and post-translocation movements was a valuable method for evaluating short-term translocation success in a freshwater environment. For future hellbender translocations, managers should prioritize selecting suitable release sites with contiguous boulder-dense areas (1-2 per m2), adequate prey (crayfish) densities (>1/m2), and habitats with low risk of predation.

More Than Meets the Eye

ABSTRACTCulturally significant landscapes, which evoke and promote strong feelings of attachment among their constituencies and advocates, pose a management challenge for federal agencies. Current cultural resources laws and policies focus largely on the physical characteristics of individual sites and features. I call here for a management approach that differs from current practice in several important ways. First, it recognizes the power of landscapes and landscape character. Drawing from both wilderness and park management, it calls for the identification and preservation of landscape characteristics, and the development of landscape-level inventories that can identify current landscape condition. Finally, it recognizes that how a landscape is experienced by its constituencies and advocates is a measure of management effectiveness. For management to succeed, management approaches must recognize and respect the core values and experiences that are at the heart of culturally significant landscapes.

Reproductive Success of Red-Billed Tropicbirds (Phaethon aethereus) on St. Eustatius, Caribbean Netherlands

The daily nest-survival rates of Red-billed Tropicbirds (Phaethon aethereus) were estimated over six breeding seasons on St. Eustatius in the Caribbean. We analyzed 338 nesting attempts between 2013 and 2020. The daily survival rate (DSR) of tropicbird nests was modeled as a function of nest initiation date, sea surface temperature (SST), elevation, vegetation in front of the nest, and year. Yearly nest survival rates (± SE) of the best fitting models ranged from 0.21 ± 0.06–0.74 ± 0.13 (n = 338 nests). DSR of the most parsimonious models averaged 0.39 ± 0.04 during the incubation period, 0.83 ± 0.05 during the chick-rearing period, and 0.30 ± 0.04 during the nesting period (incubation through fledging) when data were pooled across all years. Models with linear and quadratic trends of nest initiation date combined with SST and elevation received strong support in the incubation and nesting periods. Nests initiated in peak nesting season, when SSTs were lower, had higher DSR estimates than nests initiated early or late in the season. Compared to studies of the same species from Saba and the Gulf of California, survival probability on St. Eustatius was lower during the incubation stage but higher during the chick-rearing period. Similar to populations in the Gulf of California, tropicbird reproduction differed and laying date varied among years, and survival was influenced by SST. Our results are consistent with a study on White-tailed Tropicbirds (Phaethon lepturus) in Bermuda which found that survival was affected by temporal factors rather than physical site characteristics. Our study contributes to a better understanding of the factors that influence Red-billed Tropicbird survival on a small Caribbean island.

Influence of oyster reefs on infauna and sediment spatial distributions within intertidal mudflats

Oysters are described as estuarine ecosystem engineers because their reef structures provide habitat for a variety of flora and fauna, alter hydrodynamics, and affect sediment composition. To what spatial extent oyster reefs influence surrounding infauna and sediment composition remains uncertain. We sampled sediment and infauna across 8 intertidal mudflats at distances up to 100 m from oyster reefs within coastal bays of Virginia, USA, to determine if distance from reefs and physical site characteristics (reef elevation, local hydrodynamics, and oyster cover) explain the spatial distributions of infauna and sediment. Total infauna density increased with distance away from reefs; however, the opposite was observed for predatory crustaceans (primarily crabs). Our results indicate a halo surrounding the reefs of approximately 40 m (using an increase in ~25% of observance as the halo criterion). At 90 m from reefs, bivalves and gastropods were 70% more likely to be found (probability of observance), while there was an approximate 4-fold decrease for large crustaceans compared to locations adjacent to reefs. Increases in percent oyster reef cover and/or mean reef area did not statistically alter infauna densities but showed a statistical correlation with smaller sediment grain size, increased organic matter, and reduced flow rates. Weaker flow conditions within the surrounding mudflats were also associated with smaller grain sizes and higher organic matter content, suggesting multiple drivers on the spatial distribution of sediment composition. This study emphasizes the complexity of bio-physical couplings and the considerable spatial extent over which oyster reefs engineer intertidal communities.

Field Testing of a Putative Larviposition Pheromone for the Tsetse Fly Glossina m. morsitans Westwood

Under laboratory conditions, the alkane hydrocarbon n-pentadecane attracts gravid female tsetse (Glossina morsitans morsitans Westwood) to potential larviposition sites. We describe field-testing of this chemical, which is the first such test for any putative tsetse larviposition pheromone. We replicated randomised block experiments at 11 sites near Rekomitjie Research Station, Zambezi Valley, Zimbabwe. Each site comprised a cluster of four artificial warthog burrows constructed from 200-litre steel drums. We placed six trays, filled with sand and covered with leaf litter, inside each burrow. Both species of tsetse inhabiting this region entered these artificial burrows and deposited 1282 pupae in the trays during the experiments. In 13 experiments, n-pentadecane was tested at three different concentrations against a control. We were unable to find any conclusive evidence that the presence of n-pentadecane resulted in an increased larviposition rate for either G. m. morsitans or G. pallidipes. This finding was independent of the concentration of n-pentadecane used, and was not influenced by the presence or absence of added water, acetone or warthog urine. Any small effect of the pheromone is likely masked by the important physical characteristics of burrow larviposition sites. Order of magnitude increases in larviposition rates when leaf litter was added to larviposition sites were far greater than those due to the use of putative larviposition pheromones.

A Review of Freshwater Invertebrates as Biomonitors of Methylmercury: the Importance of More Complete Physical and Chemical Reporting.

Methylmercury (MeHg) is a toxic and bioaccumulative organo-metallic compound that is naturally produced in many ecosystems. Organisms that occupy the lower trophic positions in food webs may be key factors in the assessment of MeHg biomagnification between ecosystems. Here we present a review of the peer-reviewed literature examining MeHg bioaccumulation in freshwater invertebrates, focused principally on insects. This review aims to characterize the invertebrates that bioaccumulate higher MeHg concentrations and therefore pose a higher risk to upper trophic levels and to clarify which ecosystems are more susceptible to bioaccumulation in lower trophic levels. However, we found that few studies provided robust environmental data (notably water chemistry) as part of their papers, dramatically limiting our ability to test for factors that might contribute to different concentrations of MeHg in invertebrates. We highlight the importance of providing physical and chemical characteristics of study sites in publications examining MeHg bioaccumulation and biomagnification. Adopting the proposed recommendations will improve the available information for future mercury risk assessment analyses.

Planning green infrastructure placement based on projected precipitation data

Continued urbanization has led to tremendous changes on the landscape. These changes have exacerbated the effects of extreme climatic events such as flooding because of constrained water infiltration and increased surface flow. Typical runoff control measures involve sophisticated gray infrastructure that guide excess surface flow into storage and disposal sites. In a dynamic climate system, these measures are not sustainable since they cannot be easily modified to accommodate large volumes of runoff. Green Infrastructure (GI) is an adaptable technique that can be used to minimize runoff, in addition to offering an array of additional benefits (urban heat regulation, aesthetics, improved air quality etc.). Strategic placement of GI is key to achieving maximum utility. While physical site characteristics play a major role in determining suitable GI placement sites, knowledge of future precipitation patterns is crucial to ensure successful flood mitigation. In this paper, suitable GI sites within the city of Knoxville, Tennessee, were determined based on potential impact of an extreme flood event as indicated by site characteristics. Then, the relative potential likelihood of a flood event was determined based on projected precipitation data and knowledge of existing flood zones. By combining potential impact with likelihood information, low, medium, and high priority GI implementation sites were established. Results indicate that high priority sites are in the central parts of the city with priority decreasing outward. The GI prioritization scheme presented here, offers valuable guidance to city planners and policy makers who wish to exploit the GI approach for flood mitigation.

Site Conditions, Maintenance Costs, and Plant Performance of 10 Extensive Green Roofs in the Research Triangle Area of Central North Carolina

Compared with traditional roofing, green roofs (GRs) have quantifiable environmental and economic benefits, yet limited research exists on GR plant survival, maintenance practices, and costs related to plant performance. The objective of this study was to assess plant cover, site conditions, and maintenance practices on 10 extensive GRs in the Research Triangle Area of North Carolina. Green roof maintenance professionals were surveyed to assess plant performance, maintenance practices, and maintenance costs. Vegetation cover on each site was characterized. Relationships among plant performance and environmental and physical site characteristics, and maintenance practices were evaluated. Survey respondents ranked weed control as the most problematic maintenance task, followed by irrigation, pruning, and debris removal. No single design or maintenance factor was highly correlated with increased plant cover. Green roof age, substrate organic matter, and modular planting methods were not correlated with greater plant cover. Results showed a trend that irrigation increased plant cover. Plants persisting on GRs included several species of stonecrop (Sedum sp.), but flame flower (Talium calycinum) and ice plant (Delosperma basuticum) were also present in high populations on at least one roof each. Green roof maintenance costs ranged from $0.13/ft2 to $3.45/ft2 per year, and were greater on sites with more weeds and frequent hand watering.

Validation of the GeoWATCH soil moisture model and proposed bias correction method

The US Army is required to be a good steward of the land per US Army regulation AR 200-1. Based on this regulation, Army installations need to manage lands, to reduce potential damage and impacts to water quality and habitat that may occur from training. Maneuver training does impact the vegetation and soil and this damage is directly related to soil moisture. Soil moisture is an important factor for understanding the potential for soil surface disturbance due to vehicle impacts and predicting soil resilience to vehicle traffic, however, producing accurate estimates of the spatial and temporal variation of soil moisture has historically been elusive. GeoWATCH, which stands for Geospatial Weather-Affected Terrain Conditions and Hazards (formerly DASSP), simulates soil moisture world-wide, at relatively small spatial and temporal scales. GeoWATCH uses a physics-based downscaling approach that uses weather-scale land surface model estimates of soil moisture and land surface water and energy fluxes, with high resolution geospatial data. GeoWATCH soil moisture outputs coupled with vehicle impact models, are anticipated to be useful for near-real-time estimation of ground disturbance, but will require ground validation. To validate GeoWATCH soil moisture estimates, we utilized Soil Climate Analysis Network (SCAN) gauge network soil moisture data from 127 sites across 34 states. Statistical analysis of the raw GeoWATCH output indicated the model performs statistically better in certain soil textures. Model bias is largest for sandy soils, whereas clayey soils were least biased. As a result, bias correction models were applied to the raw GeoWATCH simulated values using linear regression to predict correction factor (CF) values based on physical site characteristics. The bias correction models significantly improved the performance of the GeoWATCH soil moisture model in terms of average performance statistics and number of statistically cally unbiased sites. This process could easily be incorporated into GeoWATCH, allowing for a capability to rapidly estimate vehicle impacts and determine rehabilitation requirements by installation land managers.

Efectos de la calidad del agua y del sustrato blando sobre la macrofauna bentónica de la zona intermareal en la Playa Pochomil, San Rafael del Sur

Se realizó un estudio espacial y temporal de la macrofauna bentónica en la zona intermareal de la Playa Pochomil, Nicaragua, en tres sitios denominados S.A (sitio arenoso), SRR (sitio rocoso con río) y S.R (sitio rocoso), respectivamente. Al final del estudio se contabilizaron un total de 596 individuos pertenecientes a cuatro Filos (Molusca, Anélida, Artrópoda y Equinodermata). La diversidad de macrofauna bentónica calculada mediante el índice de Shannon-Weaver, refleja valores de diversidad muy bajos durante todas las épocas de muestreo. Mediante el índice de Jaccard y Morisita-Horn, se evidenció que hubo baja similitud de especies. Además, se comprobó que la temporalidad no tuvo efecto directo significativo sobre la abundancia y distribución de la macrofauna bentónica, sino que ésta fue influenciada principalmente por las características físicas de los sitios de muestreo

Nesting ecology in the Hawaiian population of an endangered seabird, the Band-rumped Storm-Petrel (Oceanodroma castro)

The first confirmed nesting location of the Hawaiian population of the Band-rumped Storm-Petrel (Oceanodroma castro), an endangered seabird, was recently discovered on Hawai‘i island after decades of searching. Following the discovery, we analyzed nest site preferences of the Band-rumped Storm-Petrel at this site using a paired design. Band-rumped Storm-Petrels preferred deeper crevices compared with those available within 100 m of the nest sites. Physical and environmental characteristics of Hawaiian Bandrumped Storm-Petrel nest sites may aid conservation efforts including on-the-ground searches, removal of invasive mammalian predators, identification of potential translocation sites, and habitat restoration for this endangered species.

Galería Alcuadrado (Bogotá, Colombia): a partial history in three exhibitions

During its brief life span, the Alcuadrado art gallery (Bogotá, 2003–2009) represented an entire cohort of important contemporary artists from Colombia including Miguel Ángel Rojas, Oscar Muñoz, María Teresa Hincapié, María Elvira Escallón, Juan Fernando Herrán, François Bucher, and Jaime Ávila. Unlike most of the galleries operating in the country at the time, Alcuadrado did not have a permanent space for the display of artworks. Instead, it opted for experimental, temporary interventions in public spaces throughout the city. All of their shows created dialogues between works produced by the artists represented by the gallery, while at the same time engaging with the contexts where they were displayed. This paper provides the first chronicle of the history of this pivotal Colombian gallery by focusing on three of their exhibitions: Tres Artistas Alcuadrado, held in Bogotá in 2004 at an industrial warehouse in disuse, Campos Latinoamericanos, installed 2005 within the ruins of an unfinished Hilton Hotel building in downtown Bogotá, and Sin Remedio mounted in 2008 in a former hospital building in disuse. It studies the nomadic display model pioneered by the gallery’s directors and how it incorporated artworks into the physical and historical characteristics of several sites.

관광지의 물리적 환경특성이 관광가치 및 지역사회연계에 미치는 영향 연구 : 군산시 경암동 철길마을을 중심으로

The purpose of this study is to understand the characteristics of the tourist environment in Gunsan City and to increase the value of tourism to attract visitors' preferences and to establish links with the local community. First, based on the physical environment characteristics of the railroad village in Kyouam - dong, it is necessary to develop the physical environment characteristics by empirically identifying the causal relationship with the tourist value felt by tourists. Second, I will present the grounds for establishing tourism marketing strategy by enhancing tourism value and establishing community linkage by empirically identifying the causality that the tourism value formed through the visit of the railroad village in Kyouam - dong influences the community linkage. In order to elucidate the results of this study, a questionnaire survey was conducted to investigate the relationship between the physical environment characteristics of tourist sites and tourism value and community linkage in the railway village of Gyeongam - dong in Gunsan city. The main results of this study are as follows. First, to improve the tourism value among the characteristics of tourist environment, the most important factor is to improve the comfort. Second, accessibility affects emotional value only. Third, convenience of tourism value has no effect on all factors. Fourth, tourism value is influenced by all factors in community linkage. Emotional value has the greatest effect on tourism value. Lastly, the factors affecting the local community were convenience and accessibility.

Seedling regeneration at northern treeline, Northwest Territories tundra

Global warming has had an amplified effect in northern environments (i.e. Arctic and Subarctic regions). An indirect result of this warming is what is known as Arctic greening, which is the increase of photosynthetic material, or plant matter, in Arctic environments. How this greening trend is represented by trees at latitudinal (or northern) treeline is largely unknown. To determine how treeline may respond, I am investigating the physical environment surrounding seedlings found growing at treeline in the Northwest Territories, as well as the reproductive capacity of the mature trees in this region. Physical characteristics of sites which contain seedlings are compared to sites within the same region which do not in an attempt to determine what aspects of these environments are significant in the establishment of seedlings at treeline. Site characteristics include vegetation cover, distance to mature trees, and distance and dimensions of the nearest shrub. Reproductive capacity of mature trees is also tested to determine how significant seed viability may be in generating seedlings in this region. The limiting factor in treeline expansion may be an issue of pre-dispersal (i.e. viable seed production) as opposed to post-dispersal (i.e. seedling growth). I am conducting a germination test where I have extracted seeds from fifteen trees dispersed throughout the treeline region and have placed them under ideal growth conditions for an honest depiction of viable to unviable seed ratios. These tests may show conclusive evidence regarding what factors are contributing to treeline dynamics within a changing environment.

Egg masses of some stream‐dwelling caddisflies (Trichoptera: Hydrobiosidae) from Victoria, Australia

AbstractEggs are a largely neglected life stage in most ecological studies of aquatic insects, despite the importance of oviposition behaviour and fecundity estimates for many research questions. Incorporating egg stages into ecological research requires that ecologists can identify and quantify eggs, but descriptions of eggs and egg masses are scarce for many groups and particularly for Australian taxa. This paper focusses on stream‐dwelling caddisflies in the family Hydrobiosidae and provides species‐level identifications, morphological descriptions and images of egg masses of some species that commonly occur in south‐eastern Australia. All the species we identified laid plaque‐shaped egg masses attached to the underside of river rocks that protrude above the water surface. These egg masses can be identified in the field with the naked eye or the aid of a low‐magnification hand lens. Interspecific variations in egg mass morphology were primarily thickness and firmness of the spumaline layer, egg mass size and arrangement of eggs within the mass. We also provide some ecological information on clutch sizes and the physical characteristics of oviposition sites, and we discuss various ways in which these taxa could be exploited as model systems for ecological research.

Co-variation relations of physical soil properties and site characteristics of Finnish upland forests

Co-variation relations of physical soil properties and site characteristics of Finnish upland forests

Situating Green Infrastructure in Context: A Framework for Adaptive Socio-Hydrology in Cities.

Management of urban hydrologic processes using green infrastructure (GI) has largely focused on stormwater management. Thus, design and implementation of GI usually rely on physical site characteristics and local rainfall patterns, and do not typically account for human or social dimensions. This traditional approach leads to highly centralized stormwater management in a disconnected urban landscape, and can deemphasize additional benefits that GI offers, such as increased property value, greenspace aesthetics, heat island amelioration, carbon sequestration, and habitat for biodiversity. We propose a Framework for Adaptive Socio-Hydrology (FrASH) in which GI planning and implementation moves from a purely hydrology-driven perspective to an integrated socio-hydrological approach. This allows for an iterative, multifaceted decision-making process that would enable a network of stakeholders to collaboratively set a dynamic, context-guided project plan for the installation of GI, rather than a 'one-size-fits-all' installation. We explain how different sectors (e.g., governance, non-governmental organizations, academia, and industry) can create a connected network of organizations that work towards a common goal. Through a graphical Chambered Nautilus model, FrASH is experimentally applied to contrasting GI case studies and shows that this multi-stakeholder, connected, de-centralized network with a co-evolving decision-making project plan results in enhanced multi-functionality, potentially allowing for the management of resilience in urban systems at multiple scales.

Nest site characteristics, patterns of nest reuse, and reproductive output in an Arctic-nesting raptor, the Rough-legged Hawk

ABSTRACT Physical characteristics of nest sites are thought to influence their use by birds and the outcome of breeding attempts. The presence of preexisting nesting structures can also be an important factor influencing reuse patterns and reproductive success. We examined the relationships between nest-site physical characteristics, patterns of nest reuse, and reproductive output in Rough-legged Hawks (Buteo lagopus) breeding in the Canadian High Arctic. Because this species is a rodent specialist, we also examined the effect of variation in lemming density, their primary prey, on reproductive output. We monitored 109 nesting attempts over a 9 yr period and sampled physical characteristics of 87 known nesting sites in 53 territories on Bylot Island, Nunavut, Canada. The probability that a nest was used by a breeding pair increased with the distance to the nearest breeding conspecific, for nests sheltered by an overhang, and with lemming density. Hawk nests inaccessible to foxes and facing away from the n...