The impact of road maintenance and construction on roadside vegetation

The article provides data on the results of long-term monitoring of the state of vegetation along the main highways of Belarus, caused by environmental pollution in roadside strips with deicing reagents based on sodium chloride in winter in combination with a set of other negative factors (exhaust gases from mobile sources of pollution, changes in environmental conditions, extreme manifestations of weather and climatic factors).

Roadkills in Northern Peninsular Malaysia

As Malaysia’s economy continues to grow, an ever-expanding road network is being built to support the new developments. Whilst roads increase accessibility to resources and connect human communities, they also bring with them a host of environmental problems such as destruction and fragmentation of habitat, poaching, pollution, and roadkills. Of these, roadkills are the most direct and visible impact of building roads, yet few dedicated studies have been conducted on the extent of roadkills and how to minimize them in Malaysia. In this study, we examined the species richness and abundance of vertebrate roadkills along eight one-km stretches (two in each habitat) of highways in Terengganu and Pahang across four habitat types: rainforest, oil palm plantation, subsistence agricultural land, and village. Each stretch of highway was surveyed by walking it six times between May to October 2017 for the Terengganu segments and May to October 2018 for the Pahang segments. A total of 305 roadkilled animals were recorded, consisting of at least 24 species. Three of these are protected by Malaysian law. The most common roadkilled animals were frogs (102 individuals) followed by birds (70 individuals), mammals (67 individuals) and reptiles (66 individuals). The highest number of roadkills were recorded in roads going through villages (112 individuals), followed by oil palm plantations (81 individuals), forests (65 individuals) and subsistence agricultural land (47 individuals). For every roadkill we also recorded the location’s specific habitat and landscape characteristics such as distance to the nearest fruit tree, tree, shrub, water body, human structure, and overhead cable. Most roadkills were found close to vegetation cover and water bodies. However, we found that roadkills decreased to near zero between 30 and 80 m from the nearest shrub or tree. Roadkills decreased over larger distances from the nearest water body, but in oil palm and village habitats, reducing water bodies within 20–50 m from a road would almost half the number of roadkills. We suggest that making changes to the structure and composition of roadside vegetation and other landscape features, such as thinning vegetation to discourage wildlife from gathering near roads, could significantly reduce the number of roadkills.

Floristic composition and potential invasiveness of alien herbaceous plant in Western Mexico

Introduction: Numbers of alien plant species are rising around the globe, but not all of them become invasive. Whereas introductions have been documented for several decades in some regions of the world, knowledge on alien species in Western Mexico is limited. Here, we study roadside vegetation along an elevational gradient, which includes a protected area. Objective: We analysed the floristic composition of herbaceous alien species, their distribution patterns, and their relationship with various environmental factors. A relative importance value index (IVI) identified the most important and, therefore, probably invasive taxa. Methods: During 2017 and 2018, roadside vegetation was documented with 4-6 transects every 300 altitudinal meters, from 0 to 2 100 m, for a total of 37 transects. Each transect consisted of five 1 m² plots. All herbaceous species were registered and alien taxa identified. A cluster analysis distinguished grouping of species based on elevation. The potentially invasive species were identified by their IVI, based on the sum of relative frequency and density values. The influence of environmental variables was analysed with a canonical correspondence analysis. Results: Most alien species were grasses; other families were represented by one or two species. The species were grouped into three main clusters. The first group included rare species, the second consisted of species restricted to higher altitudes, and the third group were tropical taxa with a distribution from sea level to medium altitudes. The most important potentially invasive species were: Urochloa maxima, Melinis repens, Eragrostis ciliaris and Cynodon dactylon, all African grasses introduced for grazing. The IVI of the species was related to tree cover, leaf litter depth and surface stone cover for some species and, for others, to soil compaction, distance to major roads and elevation. Conclusions: The alien ruderal species clustered according to the general climate (temperate vs. tropical). Grasses of African origin are of highest concern as invasive species. Although most introductions are related to human disturbance, each species becomes dominant under certain environmental conditions. Thus, management programs must be specifically adjusted to each individual invasive alien.

Heavy metal accumulation by roadside vegetation and implications for pollution control

Vehicular emissions cause heavy metal pollution and exert negative impacts on environment and roadside vegetation. Wild plants growing along roadsides are capable of absorbing considerable amounts of heavy metals; thus, could be helpful in reducing heavy metal pollution. Therefore, current study inferred heavy metal absorbance capacity of some wild plant species growing along roadside. Four different wild plant species, i.e., Acacia nilotica L., Calotropis procera L., Ricinus communis L., and Ziziphus mauritiana L. were selected for the study. Leaf samples of these species were collected from four different sites, i.e., Control, New Lahore, Nawababad and Fatehabad. Leaf samples were analyzed to determine Pb2+, Zn2+, Ni2+, Mn2+ and Fe3+ accumulation. The A. nilotica, Z. mauritiana and C. procera accumulated significant amount of Pb at New Lahore site. Similarly, R. communis and A. nilotica accumulated higher amounts of Mn, Zn and Fe at Nawababad and New Lahore sites compared to the rest of the species. Nonetheless, Z. mauritiana accumulated higher amounts of Ni at all sites compared with the other species included in the study. Soil surface contributed towards the uptake of heavy metals in leaves; therefore, wild plant species should be grown near the roadsides to control heavy metals pollution. Results revealed that wild plants growing along roadsides accumulate significant amounts of heavy metals. Therefore, these species could be used to halt the vehicular pollution along roadsides and other polluted areas.

The Effects of Roadside Woody Vegetation on the Surface Temperature of Cycle Paths

The article is on the effects of woody vegetation growing on the roadside on the temperature of the surface of cycle paths. The main hypothesis of the study is that vegetation has the effect of lowering the temperature of the surroundings in its shadow and thus improves the comfort of users of cycle paths in the summer months. The second hypothesis is to find out which type of road surface is most suitable for the thermal well-being of users. This goal was achieved by measuring the temperature of selected locations on cycle paths with different types of construction surfaces with nearby woody vegetation using a contactless thermometer over several days at regular intervals. The positions of the selected locations were measured using GNSS and the whole locality of interest was photographed using an unmanned aerial vehicle (UAV), or drone, and subsequently a digital surface model (DSM) of the area was created using a Structure from Motion (SfM) algorithm. This model served for the calculation of incident solar radiation during the selected days using the Solar Area Graphics tool with ArcGIS software. Subsequently, the effect of the shade of the surrounding vegetation on the temperature during the day was analysed and statistically evaluated. The results are presented in many graphs and their interpretation used to evaluate the effects of nearby woody vegetation and the type of road surface on the surrounding air temperature and the comfort of users of these routes. The results demonstrate the benefits of using UAVs for the purpose of modelling the course of solar radiation during the day, showing the effect of roadside vegetation on reducing the surface temperature of the earth’s surface and thus confirming the need for planting and maintaining such vegetation.

Roadside Vegetation in and Around the Megacity of Kolkata Along an Urbanisation Gradient

Combustion of fossil fuels by the on-road vehicles is major contributor of air pollution which affects the surrounding vegetation and their habitat in addition to human health hazards. Study on the concurrence between vehicular greenhouse gas emissions and associated plant community is important to assess the present day problem scenario on environmental equilibrium. An ecological analysis has been carried out from five locations along roadside of the suburban interiors to the highly vehicle congested urban areas of Kolkata megacity. Quantitative study on naturally grown road side vegetation covering seedlings of tree and shrubby species, herbaceous annuals and perennials along the suitable length of each study area was conducted following standard methodology. Increasing vehicular pollution shows reciprocal correlation with species richness and species diversity. From community structure analyses across the emission gradient it was revealed that a few species exhibited tolerance to withstand increasing air contamination by successful population growth. Nevertheless, the present study might be worthwhile in assessing ecological status of the local plant communities subjected to varying level of vehicle traffic.

Study on the occlusion of the visibility window on highway exit ramps

Traffic accidents frequently occur at the nose of highway exit ramps for a variety of reasons. When attempting to take an exit, a driver’s line of sight may be obscured by the curvature or slope of the main expressway, roadside vegetation, traffic signs, and other vehicles traveling alongside. These increase the likelihood of accidents due to inaccurate or poor driver judgement when approaching a highway exit. Because of emotional responses that accompany the possibility of missing an exit, many drivers act irrationally through haphazard acceleration or braking, aggressive lane changes; in some cases, even coming to a complete stop and reversing against the flow of high speed traffic to correct their course. This study applies to curved highway exit corridors with a poor line of sight. The total visible area of the exit ramp is defined in accordance with the design specifications of both the highway routes and exit ramps, which was then further refined by considering the driving characteristics of both the drivers and of surrounding traffic. This study set out to establish a reliable occlusion model of highway exits with the following goals in mind. Geometric equations describing the area and volume of the target area of the exit ramp are established. Discrete expression equation was deployed to establish the occlusion model for the target area within the visual field. Parameters taken from specifications of the Hunan section of the Shanghai-Kunming Expressway are used for multiple calculations, in which obstruction patterns of objects with the same width, and objects with different width at different positions are analyzed. Based on the patterns observed from stimulated experiments mentioned above, multiple effective measures were proposed to prevent the obstruction of the highway exit ramp. In summary, this study provides theoretical support for prevention of obstruction as well as an anti-occlusion model for better identification of the highway exit ramps by intelligent vehicle systems.

Comparison of Attitudes Towards Roadside Vegetation Management Across an Exurban Landscape

Exurban development is the fastest growing land use across the United States (US). Its prevalence on the East Coast is susceptible to natural disaster events such as hurricanes and nor’easters. However, the socio-ecological processes related to disaster mitigation within exurban areas remain understudied. Our objective was to integrate social and landscape data to compare resident attitudes towards utility roadside vegetation management across four areas in the state of Connecticut, US. We collected data from residents using two mail surveys completed in 2017 and 2019 (n = 1962). From the survey questions, three attitude variables measured perceptions of the utility vegetation management process, and tradeoffs between protecting trees and maintaining reliable power. Across all locations, respondents with more favorable attitudes toward vegetation management were more likely to have greater knowledge about trees, and beliefs that trees should be used for human benefit; land cover characteristics and sociodemographic variables were less strongly associated with attitudes scores. Respondents differed among study areas in their preferences for aesthetics of roadside trees and their basic beliefs regarding the importance of trees. The results suggested that social processes within the exurban landscapes are spatially heterogeneous. Therefore, local variation in residential preferences for vegetation management may influence support for natural disaster management policy.