Road Proximity Research Articles

Nest‐site selection of endangered cinereous vulture (Aegypius monachus) populations affected by anthropogenic disturbance: present and future conservation implications

AbstractThe cinereous vulture Aegypius monachus is the largest bird of the western Palaearctic, and is threatened over its entire range of distribution. Considering explicitly the influence of human interference, we studied breeding habitat selection in seven breeding colonies using a geographic information system and multivariate statistical models. Steep areas far from human disturbance constituted the preferential breeding sites in all the colonies. The nesting substrate and climatic conditions varied between colonies, but always corresponded to non‐extreme climates, and included tree species of adequate size. Since human activities influenced the breeding habitat choice, there is a potential for management policies that can clearly be of benefit for the conservation of this vulture. These would fundamentally be as follows: (1) forestry activity should be oriented to protecting oak (Quercus spp.) and pine (Pinus ssp.) stands, especially individual trees of great height, and to replacing eucalyptus (Eucalyptus spp.) with autochthonous species; (2) activities (recreational, economic, etc.) around the breeding areas should be scheduled and spatially organized to avoid disturbance, particularly those deriving from the proximity of roads and tracks; (3) the expected effects of global warming should be compensated, identifying future sites where the habitat can be managed, supplementary food can be provided and reserves can be designed.

INVASIBILITY OF ROADLESS GRASSLANDS: AN EXPERIMENTAL STUDY OF YELLOW STARTHISTLE

Roadless habitats are commonly found to be less invaded than habitats near roads, but few studies have tested whether this pattern is due to propagule limitation or to greater invasion resistance of roadless sites. We examined reasons for the lower frequency and cover of yellow starthistle (Centaurea solstitialis) in grassland sites >1000 m vs. 10 m from roads in an inland California, USA, foothill landscape. During winter 2001 and 2002, we planted 100 Centaurea seeds in 64 pairs of 30 x 30 cm plots (uncleared and cleared of aboveground plant material) at sites stratified by distance from roads (10 m and >1000 m), soil type (nonserpentine and serpentine), and aspect (cool, warm, and neutral slopes). In nonserpentine grasslands, Centaurea survival was greater in uncleared (but not cleared) near (10 m) plots than in distant (>1000 m) plots. These findings suggest that the effect of distance from roads on survival corresponds with higher aboveground biotic resistance in distant sites than in near sites. Centaurea biomass was greater in near than in distant plots (both uncleared and cleared) on nonserpentine soil, suggesting that either abiotic resistance or belowground biotic resistance could limit its growth in distant sites. These distance effects were no longer significant in models that included two biotic co- variates: native grass cover (which was higher in distant sites and negatively correlated with Centaurea performance) and bare ground (which was lower in distant sites and pos- itively correlated with Centaurea performance). On serpentine soil, there was no effect of road proximity on the performance of planted Centaurea. Our results suggest that Centaurea seeds can germinate in nonserpentine and serpentine grasslands regardless of distance from roads. Beyond the seedling stage, however, biotic resistance associated with higher native grass cover and lower levels of disturbance may inhibit Centaurea invasion of nonserpentine grassland sites that are distant from roads.

Herpetofaunal species richness responses to forest landscape structure in Arkansas

Species accumulation curves were used to study relationships between herpetofaunal richness and habitat characteristics on four watersheds in Arkansas that differed markedly with respect to management intensity. Selected habitat characteristics were estimated for stands containing the sample points and within buffers with radii of 250, 500 m, and 1 km surrounding the sample points. Richness of all three herpetofaunal groups (amphibians, reptiles, and all herpetofauna) was greater in hardwood forests than in pine or mixed pine–hardwood. For all three groups, the youngest forest age class had the most species. For amphibians and total herpetofauna, richness declined as stand ages increased. Reptiles had the highest richness at sample points with the lowest class of stand basal area (BA), whereas amphibians were richest at points having the highest BA. In contrast to expectations, there was no effect of distance from water on richness of any taxa; however, we may have had incomplete data on the spatial distribution of small ponds outside the sample plots because they were not recorded in the GIS data. Results for distance to roads were ambiguous, but with more separation of compared curves as more plots were sampled, a positive influence of road proximity was suggested. There was a positive effect of buffer age diversity at the 250 m scale for all three herpetofaunal groups, but less so at scales >250 m except for amphibians, which also showed a positive effect at the 1 km scale. The two most intensively managed watersheds had higher species richness than the two less intensively managed watersheds for reptiles, amphibians, and both groups combined. In this study landscape, where urban and agricultural influences were minimal, we did not observe negative impacts of forest management and associated activities, and local habitat heterogeneity created by silviculture often had a positive effect on herpetofaunal species richness.

The Impacts of Sprawl on Biodiversity: the Ant Fauna of the Lower Florida Keys

Sprawling development can affect species composition by increasing the rate of invasion by non-native species, and decreasing the persistence of native species. This paper briefly reviews the scientific literature on the impacts of sprawl on biological diversity, with specific emphasis on the influence of sprawl on non-native species richness. We then explore the relationship between sprawl and biodiversity using a data set of ant species collected from 46 habitat patches located in the increasingly suburbanized Florida Keys, USA. We quantified sprawl as the proximity of roads and amount of development surrounding a habitat patch. Using bait transects, we identified 24 native and 18 non-native species of ants. Neither the overall number of native species nor the number of rare native species were significantly affected by the amount of development or proximity to roads, however, the number of non-native species was significantly correlated with the amount of development. Surprisingly, the number of native species and rare native species was significantly positively correlated with the number of non-native species. Areas that supported many species of native ants also supported a diverse non-native ant fauna, and the species distribution was highly nested. Currently, the native ant fauna of the Florida Keys does not appear to be dramatically influenced by sprawl, however, if development increases, the number of non-native ants may increase, and many of these species have been documented as decreasing native ant diversity. If development plateaus, there is evidence that the native ant fauna could persist and could decrease non-native species richness through competition or predation.

AMPHIBIAN ROAD MORTALITY IN RESPONSE TO NIGHTLY VARIATIONS IN TRAFFIC INTENSITY

Pond-breeding amphibians frequently encounter roads during their movements across the landscape to reach their breeding, summering, or hibernation sites. Through night driving surveys conducted each summer from 1995-2002 on a 20-km stretch of secondary road within a national park of eastern Canada, I evaluated whether road traffic had cumulative effects on amphibian abundance over this period. I also investigated the effect of nightly variations in traffic intensity on the number of amphibians killed on the road. I recorded a total of 4643 amphibian crossing events during the 37 surveys. I did not detect any decreasing trend in abundance for amphibian roadside populations over the 8 years. The number of dead American toads (Bufo americanus) increased with increasing traffic intensity. The number of ranid frogs (Rana clamitans, R. pipiens, and R. sylvatica) dead on the road was greatest when many individuals were moving on the road and at moderate traffic intensities (approximately 10-18 vehicles/h). In contrast, spring peepers (Pseudacris crucifer) dead on the road increased with decreasing traffic intensity. The number of ambystomatid salamanders (Ambystoma laterale and A. maculatum) dead on the road, on the other hand, did not respond to traffic intensity. Nonetheless, results indicate that subtle variations in traffic intensity as those observed in this study (i.e., 5-26 vehicles/h) can increase mortality on the road for certain amphibian species. Future studies in landscape ecology should routinely consider measures associated with roads, such as the proximity and density of roads, when investigating amphibian abundance patterns in wetlands.

Landscape context influences salt marsh bird diversity and area requirements in New England

We evaluated the contributions of spatial distribution, juxtaposition, and quality of salt marsh habitat to salt marsh breeding birds along the New England coast, USA. We divided the region into two landscapes, Long Island Sound and the Gulf of Maine, based on latitude, geologic and human land use histories, and physical characteristics (tidal amplitude, wave energy). Species richness in both landscapes was at least 20% greater on larger salt marshes. Response to marsh isolation and human development varied regionally, with bird species more sensitive to marsh isolation and road proximity in the more pristine (Gulf of Maine) than altered (Long Island Sound) region. Relatively little overlap was evident between regions in predictors of occurrence and effects of marsh area on particular species. These results indicate that: (1) salt marsh bird communities show similar associations with habitat area and isolation as do forest, grassland, and freshwater wetland bird communities, and (2) landscape context mediates the influence of these parameters on the avian community and should be considered when defining the habitat requirements of salt marsh breeding birds.

Le pinson du Nord Fringilla montifringilla L.: un visiteur d'exception dans les forêts d'Ajoie durant l'hiver 2001–2002 | The brambling Fringilla montifringilla L.: a rare visitor in the forests of Ajoie in winter 2001/2002

In the winter of 2001/2002, over a period lasting 110 days, ten to twelve million bramblings (northern Eurasian finches)sought a place to sleep in the region of Villars-sur-Fontenais in Canton Jura, Switzerland. Suitable resting places in the proximity of access roads enabled a great number of ornithologists to carry out regular and numerous observations that were collected by the author in Jura's Natural Science Museum in Porrentruy. A lot of new information on the behaviour of the bramblings at their places of rest was collected, both during the day, on their return, and was also closely observed and described with regard to weather conditions and the change of season. Information was also collected on the ethology of predators. The special aspect of the article is the visit to the resting places after the departure of the bramblings. Much new knowledge was gained from this. Pseudombrophila stercofringilla,a newly discovered Ascomyzete, was actually found by its discoverer in situ. The effect was detected of uric acid,which turned the ground plants brown and destroyed fir needles from the previous year. It would be a worthwhile subject of scientific inquiry to study the effect of enrichment with fertiliser – manifest on trees and mushrooms. A regional study would make it possible to examine whether the scratching activity of the bramblings, allowing beechnuts to fall on fruitful ground, have a positive effect of regeneration of beech forests in the long term.

Predictive models of habitat preferences for the Eurasian eagle owl Bubo bubo: a multiscale approach

Habitat preference of eagle owls Bubo bubo were examined through comparing habitat composition around 51 occupied cliffs and 36 non‐occupied cliffs in Alicante (E Spain). We employed Generalized Linear Models to examine patterns of habitat preference at three different spatial scales: nest site (7 km2), home range (25 km2), and landscape (100 km2). At the nest site scale, occupied cliffs were more rugged, had a greater proportion of forest surface in the surroundings, and were further from the nearest paved road than unoccupied cliffs. Additionally, probability of having an occupied cliff increased when there was another occupied territory in the surroundings. At both the home range scale and the landscape scale, high probabilities of presence of eagle owls were related to high percentages of Mediterranean scrubland around the cliffs, which are the preferred habitat of European rabbits Oryctolagus cuniculus, the main prey of the owls. We suggest a hierarchical process of habitat selection in the eagle owl concerning suitable trophic resources at the broadest scales and adequate sites for breeding and roosting at the smallest scale. However, it should be noted that some structural features such as the proximity of roads were not necessarily avoided by the owls, but their presence were possibly constrained by systematic killing of individuals. Our paper provides new evidence for the requirement of multi‐scale approaches to gain insight into both the different limiting factors for the persistence of populations and the role of individual perception of the environment in the evolution of habitat selection.

Adverse respiratory effects and allergic susceptibility in relation to particulate air pollution: flirting with disaster.

Adverse respiratory effects and allergic susceptibility in relation to particulate air pollution: flirting with disaster.

Influence of the proximity and amount of human development and roads on the occurrence of the red imported fire ant in the lower Florida Keys

We examined the influence of both the proximity and extent of human developments and paved roads on the presence of the predatory, non-indigenous, red imported fire ant ( Solenopsis invicta). This species was inadvertently introduced into the United States at the port of Mobile, Alabama, around 1930 and rapidly spread to many southeastern states, including Florida. More recently, S. invicta colonized the Florida Keys, an area with a high proportion of rare and endemic vertebrate and invertebrate species. We placed bait transects in transitional salt-marsh, pineland, and hardwood hammocks on 13 of the lower Florida Keys and compared habitat type, the shortest distance of the bait transect to a development or road, and area of development and roads 50, 70, 100, and 150 m around each bait transect for areas with and without red imported fire ants. Red imported fire ants were detected on 21 of the 80 transects and were equally abundant in all habitat types. While all of the development and road variables differed significantly between bait transects with and without red imported fire ants, transects that were closest to roads and that had the largest amount of development within a 150 m radii had the highest probability of presence of red imported fire ants. Recovery efforts for endangered species in areas invaded by red imported fire ants should include analyses of the cumulative impacts of roads and developments in areas near protected lands.

Reduced bird occurrence in pine forest fragments associated with road proximity in a Mediterranean agricultural area

This study investigated the effect of road and highway proximity on the occurrence of bird species in isolated secondary pine forest fragments in an agricultural matrix. We assessed the effects of road proximity separately for three different groups of bird species in order to detect ecological responses related to species biology. Bird occurrence was mainly related to fragment size but also to vegetation structure and fragment connectivity. When corrected for patch characteristics, we found that fragments up to 2 km away from a main highway contained less forest species, both generalists and specialists than fragments more distantly located. This pattern was independent of the side of the highway analysed. Considering each bird species separately, we found consistent lower occurrence probabilities near the highway in 50% of forest species. This difference was not found for ubiquitous species that were to some extent positively influenced by proximity of other major roads. Our results suggest that highway proximity, but not that of other major roads, decrease occupancy probability of forest birds in isolated forest fragments, thus reducing probability of metapopulation persistence. Although low habitat quality as a result of noise disturbance is likely to account for some of the results, the long distance effect detected strongly suggests that other factors rather than direct traffic disturbance alone are involved in lower bird occurrences near the highway. Decreased connectivity among forest fragments associated to avoidance of areas near the highway is an alternative explanation to the results obtained. We suggest that these findings should be included in strategic environmental impact assessment studies conducted to determine the ecological impact of large transport infrastructures across highly fragmented landscapes.

Relationships between Nitrogen Dioxide Personal Exposure and Ambient Air Monitoring Measurements among Children in Three French Metropolitan Areas: VESTA Study

In epidemiological studies, investigators have routinely used ambient air concentrations, measured by air-quality monitoring networks, to assess exposure of subjects. When there is great spatial variability of ambient air concentrations or when there are specific indoor exposures, this approach may yield substantial exposure misclassification and distort the associations between exposure and the health endpoints of interest. In 3 French metropolitan areas, the cross-sectional relationships between 48 hr of nitrogen dioxide personal exposure of 73 children and the corresponding 48-hr background ambient air concentrations were analyzed. The crude correlation between ambient air concentrations and personal exposures was poor in all cities (r2 = .009 for Grenoble, r2 = .04 for Toulouse, and r2 = .02 for Paris). These correlations were improved when the authors took into account other ambient air or indoor air sources of nitrogen dioxide emissions (the corresponding multiple linear regression, r2, increased to .43 in Grenoble, .50 in Toulouse, and .37 in Paris). The main variables that explained personal exposures were an index of traffic intensity and proximity and use of a gas cooker at home. The results of this study confirm that ambient air-monitoring site measurements are poor predictors of personal exposure. Investigators should carefully characterize the proximity of roads occupied by dense traffic to the home/school as well as indoor sources of nitric oxide emissions; both of these careful characterizations will assist researchers in the prediction of personal exposure in epidemiological studies.

Vertical dispersion of suspended particulates in urban area of Hong Kong

Field data are used to evaluate the vertical distribution of suspended particulates at different height levels in an urban area of Hong Kong. Four buildings in different street configurations and street environments were selected. According to the street configuration, they are classified into two groups: street canyon and open street. In street canyon, TSP and PM 10 concentration varies with height exponentially. However, the rate of TSP, PM 10 and PM 2.5 decrease with distance from the ground floor is in decreasing order of TSP, PM 10 and PM 2.5. The particulate matter dispersion in street canyon is affected by the prevailing wind direction and the street configuration in particular the height-to-width ratio. In open streets, the vertical concentration depends on the vertical mixing, local dilution and other external factors such as sea breeze, as well as the proximity of trunk road and construction activity. Fine particulates contribute a major part of suspended particulates in Hong Kong and the impact can penetrate to the tenth floor and above. The PM 2.5 level is high in Hong Kong and above 80% of the PM 2.5 recorded in this field study exceeded the EPA NAAQS standards.

Analysis of incidence of childhood cancer in the West Midlands of the United Kingdom in relation to proximity to main roads and petrol stations.

OBJECTIVES: To investigate whether there is an excess of leukaemias in 0-15 year old children among those living in close proximity (within 100 m) of a main road or petrol...

Environmental impact prediction using neural network modelling. An example in wildlife damage

1. Decision making in management of environmental impact confronts the problem of analysing relationships in highly complex ecological systems. These relationships are generally non‐linear, and conventional techniques do not apply satisfactorily. The problem is equivalent to that of predicting the output of a black box. Artificial neural networks (ANN) have shown tremendous promise in modelling such situations. 2. The present work describes the development and validation of an ANN in modelling wildlife damage to farmland, a particular instance of ecological impact. An ANN approach was developed and tested using data from 200 damaged plots, and a control sample of 20 undamaged plots, described by 17 environmental characters. The dependent variable was the financial cost of impact per plot. 3. The predictive quality of the ANN models was evaluated through the ‘leave‐one‐out’ procedure. For 82% of predicted values, deviation from observed values is lower than 1780, that is 10% of the range of the observed values. The frequency of bad predictions depends on the minimum level of impact (critical effect size) considered. In France, compensation is given starting from a minimum level of 200 FF. At this level, the frequency of occurrence of Type I errors (predicted impact does not occur) is 7·11%. Different strategies of prevention of impact, using different threshold values for prevention, are analysed. Frequency of Type I errors increases, and that of Type II errors (occurrence of unpredicted impact) decreases as the threshold for prevention increases. 4. Sensitivity analysis allows the determination of the effect of seven quantitative variables on the cost of damage compensation. Proximity of a paved road, proximity and number of houses, and number of other buildings contribute negatively, and three other variables (proportion of the perimeter of the plot occupied by woody vegetation, density of the vegetation, and density of wild boar in the surrounding area) contribute positively to the predicted value. 5. Results show that the utility of impact prediction for prevention depends on the cost of errors and the absolute cost of prevention. 6. Finally, ANNs proved able to learn complex relationships between environmental variables and impact assessment, and to produce operationally relevant predictions. Good predictions can help managers to distribute efficiently their actions between prevention, protection and compensation.

Animals as sentinels of human health hazards of environmental chemicals.

A workshop titled "Using Sentinel Species Data to Address the Potential Human Health Effects of Chemicals in the Environment," sponsored by the U.S. Army Center for Environmental Health Research, the National Center for Environmental Assessment of the EPA, and the Agency for Toxic Substances and Disease Registry, was held to consider the use of sentinel and surrogate animal species data for evaluating the potential human health effects of chemicals in the environment. The workshop took a broad view of the sentinel species concept, and included mammalian and nonmammalian species, companion animals, food animals, fish, amphibians, and other wildlife. Sentinel species data included observations of wild animals in field situations as well as experimental animal data. Workshop participants identified potential applications for sentinel species data derived from monitoring programs or serendipitous observations and explored the potential use of such information in human health hazard and risk assessments and for evaluating causes or mechanisms of effect. Although it is unlikely that sentinel species data will be used as the sole determinative factor in evaluating human health concerns, such data can be useful as for additional weight of evidence in a risk assessment, for providing early warning of situations requiring further study, or for monitoring the course of remedial activities. Attention was given to the factors impeding the application of sentinel species approaches and their acceptance in the scientific and regulatory communities. Workshop participants identified a number of critical research needs and opportunities for interagency collaboration that could help advance the use of sentinel species approaches.

The Effects of Car Traffic on Breeding Bird Populations in Woodland. III. Reduction of Density in Relation to the Proximity of Main Roads

1. This study investigated the effect of car traffic on the breeding density of birds in deciduous and coniferous woodland, and the importance of noise and visibility of cars as possible factors affecting density. 2. Of the 43 species analysed in both woodland types, 26 species (60%) showed evidence of reduced density adjacent to roads (based on analysis with Wilcoxon signed-ranks test and regression). 3. Regression models with noise load as the only independent variable gave the best overall results. Calculated «effect distances» (the distance from the road up to where a reduced density was present) based on these regressions varied between species from 40-1500 m for a road with 10 000 cars per day to 70-2800 m for a road with 60 000 cars per day (120 km h −1 and 70% amount of woodland along the road). For a zone of 250 m from the road the reduction of the density varied from 20 to 98%. 4. When visibility of cars was controlled for, the number of species showing density reductions was much higher on plots with a high noise load than on ones with a low noise load. When noise conditions were held constant, however, there was no difference in bird densities between plots with high and low visibility of cars. 5. It is argued that noise load is probably the most important cause of the reduced densities. Visibility of cars, direct mortality and pollution are considered unimportant. 6. The results of this study stress the importance of considering the effect of car traffic on the breeding density of birds in planning and constructing main roads

Habitat selection by the little bustard Tetrax tetrax in cultivated areas of Central Spain

Habitat selection of the little bustard Tetrax tetrax during the breeding season was analysed in four cultivated areas of Central Spain. Little bustards preferred long-fallow land, legume crops and fallow land. Cereal crops, ploughed land and shrubland were avoided. One of the most important habitat requirements was vegetation whose average height does not exceed 20 cm. The species shows some tolerance to the proximity of buildings, villages and roads. Conservation implications are discussed.

Soils and settlement location in 18th century colonial Tidewater Virginia

A case demonstrating the importance of soils as an attractive force in site location is constructed from a review of soil literature and agriculture practices. Since tobacco cultivation was the dominant economic activity in rural Tidewater Virginia, the environmental requirements of the tobacco plant heavily influenced the colonists’ site location decisions. Environmental and social factors, featuring the proximity of navigable water, roads, drinking water, nearest neighbor, and soil type were compared. The results confirmed the primacy of the role of soils in the decision of site location in a tobacco-based economy.

Lead content of household dust from a city in Iraq

Abstract More than seventy samples of household dust from residential apartments of Erbil(Iraq) were analysed for their lead content. All the dust samples were found to contain sufficiently high concentrations of lead. The highest recorded concentration was 1102 μg and the lowest was 151 μg of lead per gram of air dry dust. Apartments in the city centre were containing highest concentrations of lead> apartments along a highway> apartments besides secondary roads and the lowest concentrations were recorded for samples from apartments in the proximity of roads with nominal traffic. Along the highway, highest concentrations of lead were recorded for dust samples from 50 m. Next place was occupied by the samples from 60 m.