City climate and landscape structure shape pollinators, nectar and transported pollen along a gradient of urbanization

Urbanization gradients influence both landscape and climate and provide opportunity for understanding how species, especially plants and pollinators, respond to artificially driven environmental transitions. Here, we investigated several aspects of pollination along an urbanization gradient in landscape and climate. We quantified wild hoverfly and bee abundances with trapping, standing crop of nectar with spectrophotometer, and the pollen transported by flower-visitors with DNA-metabarcoding, in 40 independent sites from seminatural to built-up areas in Northern Italy. Linear and nonlinear relationships were detected along the urbanization gradient. Pollinator abundances increased until 22% of impervious surface, dropping by 34% after that, and it also decreased with green patch distance and urban park size. Thus, suburban landscapes host more pollinators than highly cemented or seminatural areas. Moreover, pollinators diminished by up to 45% in areas with low temperature seasonality: urbanized areas likely posing thermic stress. Furthermore, the sugar mass available in nectar increased by 91% with impervious cover, indicating that city nectars were less consumed or flowers more productive. Furthermore, the species richness of pollen decreased by 32% in highly urbanized areas, and with a high incidence of exotic plants, hinting for anthropized plant communities. Synthesis and applications: Urbanization influences pollinator abundances, nectar resources and transported pollen. Pollinators are negatively affected by a thermally harsh climate in highly urbanized areas with isolated green areas and large parks. Suburban landscapes demonstrated the highest pollinator presence. In the city core, flowers contained more nectary sugar, while pollinators collected pollen from a small number of plants, mainly exotic. These findings highlight the influence of urban landscape structure and climate on pollinators and plants, showing that cities are heterogenous realities. Patterns from this study will serve as basis for pollinator-friendly planning and management of urban landscapes.

Effect of Land Surface Temperature on Urban Heat Island in Varanasi City, India

Crucial changes in urban climate can be witnessed due to rapid urbanisation of cities across the world. It is important to find a balance between urban expansion and thermal environment quality to guarantee sustainable urban development. Thus, it is a major research priority to study the urban heat island (UHI) in various fields, i.e., climate change urban ecology, urban climatology, urban planning, mitigation and management, urban geography, etc. The present study highlighted the interrelationship between land surface temperature (LST) and the abundance of impervious cover and green cover in the Varanasi city of Uttar Pradesh, India. For this purpose, we used various GIS and remote-sensing techniques. Landsat 8 images, land-use–land-cover pattern including urban/rural gradients, and grid- and metric-based multi-resolution techniques were used for the analysis. From the study, it was noticed that LST, density of impervious cover, and density of green cover were correlated significantly, and an urban gradient existed over the entire city, depicting a typical UHI profile. It was also concluded that the orientation, randomness, and aggregation of impervious cover and green cover have a strong correlation with LST. From this study, it is recommended that, when planning urban extension, spatial variation of impervious cover and green cover are designed properly to ensure the comfort of all living beings as per the ecological point of view.

How Surface Water Management Can Benefit Fish Conservation in Urban Streams

We analyzed 33 y of fish community data collected from a low-order, urban stream in central Illinois, USA, to determine the effects of municipal wastewater management projects and urbanization on fish communities. From 1985 to 2017, species richness, number of pollution-intolerant species, and alternative index of biotic integrity significantly increased at sites across this system. Species diversity likewise increased, but was mostly significant only at sites downstream of the effluent outflow. Ceasing the chlorination of wastewater in 1990 resulted in significant increases in fish community metrics both upstream and downstream of effluent outflow, although effects varied from site to site. Completing a combined sewer overflow abatement project in 2008 resulted in some significant increases in species richness, diversity, and number of pollution-intolerant species at sites downstream of effluent outflow. From 2001 to 2016, the change in the number of pollution-intolerant species correlated inversely with the increased percentage of impervious cover in the study system. There was no significant correlation of other metrics with the change in percent impervious surfaces. These results suggest that urbanization at upstream sites limited to some extent the benefits of water management interventions that improved fish community metrics at downstream sites.

Development and Assessment of Watershed Management Indicators Using the Budyko Framework Parameter

This study aims to introduce the Budyko curve’s parameter (w) as a watershed quality indicator and establish criteria. Basin-specific (w) was calculated in 183 watersheds based on land use in 2013. Weather data and runoff data were used, and runoff data were calculated using Hydrological Simulation Program-Fortran (HSPF). An estimation model was developed to estimate the w of the unmeasured watershed, and the R2 of the developed model was 0.917, showing that the modeled value was reliable. A cluster analysis between basin-specific w and impervious area ratio in 2013 was performed to classify watershed quality. w was classified into four grades according to the dendrogram and impervious cover model. Watershed quality in 1975 and 2013 was evaluated using the developed indicators and criteria. The quality grades of 30 watersheds deteriorated, and the deteriorated watershed increased built-up and decreased forest and grass. To evaluate the indicators’ applicability, the low impact development (LID) method was applied to HSPF to confirm the indicator and criteria changes. It showed that the watershed to which LID was applied has improved indicator and reduced grade. The indicator developed in this study is expected to be useful for watershed quality assessment and analysis of improvement effects according to watershed management.

The Rome gas blowout zone (Central Italy)

<p>Colli Albani is an alkali-potassic quiescent volcano of Central Italy that last erupted 36 ka ago. Several lahar generating water overflows have occurred from Albano crater lake, the most recent in Roman times (IV Century B.P.) and the resulting deposits form a surficial impermeable cover on its north-western flank. An important NW-SE trending volcano-tectonic fracture extends from the volcano to the periphery of Rome city. This is a leaky fracture allowing deep magmatic gas to rise toward the surface. In zones where the impervious cover has been removed by excavations, as Cava dei Selci, the gas is freely discharged into the atmosphere creating local hazardous conditions. Elsewhere, the gas dissolves and pressurizes the shallow aquifer confined underneath the impervious cover. Any time this aquifer is reached by a drilling, a dangerous gas blowout may be generated, i.e. a sudden emission of a jet of gas, nebulized water and fine loose fragments of volcanic rocks. Since 2003 four gas blowouts, from ~ 45–50 m deep drillings, have occurred at the boundary between Rome and Ciampino municipalities, a site designed as the Rome gas blowout zone. Dangerous atmospheric CO<sub>2</sub> and H<sub>2</sub>S concentrations killed some animals and several families had to be evacuated because of hazardous gas concentration inside their houses. The emitted gas consists mostly of CO<sub>2</sub> (>90 vol.%) and contains a low but significant quantity of H<sub>2</sub>S (0.3–0.5 vol.%); it has the highest helium isotopic R/Ra value (up to 1.90) of all Colli Albani natural gas discharges. This He isotopic value is similar or even slightly higher than in the fluid inclusions of phenocrysts of the Colli Albani volcanic rocks, suggesting a likely magmatic origin of the gas. Colli Albani volcano is characterized by anomalous uplift, release of magmatic gas and episodic seismic crises. The Rome gas blowouts represent a geochemical window to investigate deep volcanic processes. Should a volcanic unrest occur, gas hazard would increase in this densely inhabited zone, as the input of magmatic gas into the confined aquifer might create overpressure conditions leading to a harmful phreatic explosion, or increase the emission of hazardous gas through newly created fractures.</p>

Fully Convolutional Neural Network for Impervious Surface Segmentation in Mixed Urban Environment

The urgency of creating appropriate, high-resolution data products such as impervious cover information has increased as cities face rapid growth as well as climate change and other environmental challenges. This work explores the use of fully convolutional neural networks (FCNNs )—specifically UNet with a ResNet-152 encoder—in mapping impervious surfaces at the pixel level from WorldView-2 in a mixed urban/residential environment. We investigate three-, four-, and eight-band multispectral inputs to the FCNN. Resulting maps are promising in both qualitative and quantitative assessment when compared to automated land use/land cover products. Accuracy was assessed by F1 and average precision (AP) scores, as well as receiver operating characteristic curves, with area under the curve (AUC ) used as an additional accuracy metric. The four-band model shows the highest average test-set accuracies (F1, AP, and AUC of 0.709, 0.82, and 0.807, respectively), with higher AP and AUC than the automated land use/land cover products, indicating the utility of the blue-green-red-infrared channels for the FCNN. Improved performance was seen in residential areas, with worse performance in more densely developed areas.

Multiscale determinants of Pacific chorus frog occurrence in a developed landscape

Pacific chorus frog (Pseudacris regilla) populations have persisted despite urban and rural development throughout the species’ range; yet it is possible that P. regilla, like other anurans with which it historically co-occurred, will become extirpated from cities and suburbs if urbanization intensifies as predicted. An improved understanding of the conditions that enable this species to persist in developed landscapes is needed to identify and conserve suitable habitats. We investigated species-habitat relationships for P. regilla in a mixed urban-rural landscape in southwestern British Columbia, Canada, to identify potential criteria for habitat suitability. We conducted repeat auditory surveys of chorusing males at 52 potential breeding wetlands and modeled occupancy at 26 of these sites using local and landscape variables representing competing hypotheses and spatial scales of influence. The models that best explained P. regilla occupancy included a combination of terrestrial habitat and connectivity factors and the presence of non-native predators. We found that the proportion of impervious cover within 250 m of a wetland had the strongest negative impact on occupancy. Our findings suggest that availability of terrestrial habitat adjacent to breeding sites is the primary driver of species presence in the developed landscape. Conservation efforts should seek to limit impervious cover to less than 20% within a 250-m buffer around breeding wetlands. Further, restored and created wetlands in urban and rural areas may be more likely to support P. regilla if they are designed with a seasonal hydroperiod that excludes non-native aquatic predators and are placed in an area of high pond density.