•An application of i-Tree Eco model in Strasbourg city to assess air pollution removal by trees in public green spaces across Strasbourg city was conducted.•The contribution of urban trees in air ...pollution removal is small in comparison with local emission rates in Strasbourg city.•Public trees of Strasbourg remove about 7% of the emitted PM10coarse in the city’s atmosphere.
This study integrates i-Tree Eco model in order to estimate air pollution removal by urban trees in Strasbourg city, France. Applied for the first time in a French city, the model shows that public trees, i.e., trees managed by the city, removed about 88t of pollutants during one year period (from July 2012 to June 2013): about 1 ton for CO; 14 tons for NO2; 56 tons for O3; 12 tons for PM10coarse (particles with diameter ranging from 2.5 to 10μm); 5 tons for PM2.5 and 1 ton for SO2. Air pollution removal varied mainly with the tree cover and the level of air pollutants concentrations. Comparison between simulated pollution removal rates and local emissions shows that public trees of Strasbourg reduce about 7% of the emitted PM10coarse in the city’s atmosphere; however, effect on other air pollutants is small. Thus, our study reveals that urban trees are a significant element to reduce air pollution but are not the only solution to this problem. It’s then recommended to associate planting and managing urban forest resources to other strategies that take into account the urban environment characteristics: built structures, street design, location of local sources; etc.
Urban ecology is a field encompassing multiple disciplines and practical applications and has grown rapidly. However, the field is heterogeneous as a global inquiry with multiple theoretical and ...conceptual frameworks, variable research approaches, and a lack of coordination among multiple schools of thought and research foci. Here, we present an international consensus on how urban ecology can advance along multiple research directions. There is potential for the field to mature as a holistic, integrated science of urban systems. Such an integrated science could better inform decisionmakers who need increased understanding of complex relationships among social, ecological, economic, and built infrastructure systems. To advance the field requires conceptual synthesis, knowledge and data sharing, cross-city comparative research, new intellectual networks, and engagement with additional disciplines. We consider challenges and opportunities for understanding dynamics of urban systems. We suggest pathways for advancing urban ecology research to support the goals of improving urban sustainability and resilience, conserving urban biodiversity, and promoting human well-being on an urbanizing planet.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The paradigm shift towards very high spatial resolution was smoothly achieved at least at thebeginning. The improvement of the spatial resolution should lead to a better match between realityand its ...pixel representation. Has urban research been more effective? Have we really broughtanother vision of the territories or influenced planning practices? Has the image become anelement of decision-making? What are the impacts of this digital revolution that we are facing?Imagery has positioned itself as a must in many fields, it remains an unparalleled medium ofinformation and the offer embraces a multitude of possibilities. The current digital transitionoffers us the opportunity to look at the latest developments.
Le changement de paradigme vers la très haute résolution spatiale (THRS) a été réalisé en douceur tout au moins au début. L'amélioration de la résolution spatiale devait aboutir à une meilleure adéquation entre la réalité et sa représentation pixellaire. On allait pouvoir cartographier, analyser suivre dans le temps les dynamiques des paysages, et plus particulièrement le volet urbain qui enfin se dévoilerait. La recherche urbaine at -elle été réellement plus performante ? L'image est-elle devenue un élément de prise de décision ? Quels sont les impacts de cette révolution numérique auxquels nous faisons face ? Les enjeux sont plus nombreux mais sommes-nous mieux armés pour proposer quelques solutions ? La transition numérique actuelle nous offre la possibilité d'un regard sur les dernières évolutions qu'il serait intéressant d'étudier. Mots clés observation de la Terre, systèmes urbains, pratiques territoriales, transition numérique Abstract The paradigm shift towards very high spatial resolution was smoothly achieved at least at the beginning. The improvement of the spatial resolution should lead to a better match between reality and its pixel representation. Has urban research been more effective? Have we really brought another vision of the territories or influenced planning practices? Has the image become an element of decision-making? What are the impacts of this digital revolution that we are facing? Imagery has positioned itself as a must in many fields, it remains an unparalleled medium of information and the offer embraces a multitude of possibilities. The current digital transition offers us the opportunity to look at the latest developments.
In 2018, the International Tracing Service (ITS) extends the online accessibility of further parts of its 30 million documents on the fate of Holocaust victims, of forced laborers and Displaced ...Persons. To support the understanding of this historical documentation the ITS developed a so-called e-Guide - an interactive tool for describing document types, their origin, the meaning of terms and the possible variations. This paper introduces the concept thoughts behind the e-Guide and the first results. Using the Malariakartei as a practical example, the article will show how different user groups can benefit from the new digital guide.
Blind source separation is a common processing tool to analyse the constitution of pixels of hyperspectral images. Such methods usually suppose that pure pixel spectra (endmembers) are the same in ...all the image for each class of materials. In the framework of remote sensing, such an assumption is no longer valid in the presence of intra-class variability due to illumination conditions, weathering, slight variations of the pure materials, etc. In this paper, we first describe the results of investigations highlighting intra-class variability measured in real images. Considering these results, a new formulation of the linear mixing model is presented leading to two new methods. Unconstrained pixel-by-pixel NMF (UP-NMF) is a new blind source separation method based on the assumption of a linear mixing model, which can deal with intra-class variability. To overcome the limitations of UP-NMF, an extended method is also proposed, named Inertia-constrained Pixel-by-pixel NMF (IP-NMF). For each sensed spectrum, these extended versions of NMF extract a corresponding set of source spectra. A constraint is set to limit the spreading of each source’s estimates in IP-NMF. The proposed methods are first tested on a semi-synthetic data set built with spectra extracted from a real hyperspectral image and then numerically mixed. We thus demonstrate the interest of our methods for realistic source variabilities. Finally, IP-NMF is tested on a real data set and it is shown to yield better performance than state of the art methods.
Earth observation data are becoming available at increasingly finer resolutions. Sensors already in existence (IKONOS, Quickbird, SPOT 5, Orbview) or due to be launched in the near future will reach ...1-5 m resolution. These very high resolution (VHR) data will provide more details of the urban areas, but it seems evident that they will create additional problems in terms of information extraction using automatic classification. In this framework, this paper examines the potential of the spectral/textural approach to improve the classification accuracy of intra-urban land cover types. The utility of the textural analysis was measured in comparison with multi-spectral per-pixel classifications. Haralick's second-order statistics were applied to the co-occurrence matrix. Four texture indices with six window sizes created from panchromatic images were tested on images at high to very high resolutions (10-1 m). The results show that the optimal index improving the global classification accuracy is the homogeneity measure, with a 7×7 window size. Moreover, for 1 m images, texture measure of homogeneity allows one to decrease the shadows.
High-spectral-resolution hyperspectral data are acquired by sensors that gather images from hundreds of narrow and contiguous bands of the electromagnetic spectrum. These data offer unique ...opportunities for characterization and precise land surface recognition in urban areas. So far, few studies have been conducted with these data to automatically detect and estimate areas of photovoltaic panels, which currently constitute an important part of renewable energy systems in urban areas of developed countries. In this paper, two hyperspectral-unmixing-based methods are proposed to detect and to estimate surfaces of photovoltaic panels. These approaches, related to linear spectral unmixing (LSU) techniques, are based on new nonnegative matrix factorization (NMF) algorithms that exploit known panel spectra, which makes them partial NMF methods. The first approach, called Grd-Part-NMF, is a gradient-based method, whereas the second one, called Multi-Part-NMF, uses multiplicative update rules. To evaluate the performance of these approaches, experiments are conducted on realistic synthetic and real airborne hyperspectral data acquired over an urban region. For the synthetic data, obtained results show that the proposed methods yield much better overall performance than NMF-unmixing-based methods from the literature. For the real data, the obtained detection and area estimation results are first confirmed by using very high-spatial-resolution ortho-images of the same regions. These results are also compared with those obtained by standard NMF-unmixing-based methods and by a one-class-classification-based approach. This comparison shows that the proposed approaches are superior to those considered from the literature.
Characterizing urban climate in hot arid cities is a key step to understand the interactions of climatic variables with the built-up and the vegetation. Extreme heat waves in summer are a strong ...stress especially for heat-vulnerable populations such as young children, the elderly and the sick. Urban Heat Island (UHI) in hot arid regions shows some specific features compared to other regions. Vegetation is known to play a role in alleviating urban heat island especially in hot arid climates. This study aims to analyse intra-urban microclimatic variations and the impact of vegetation in the arid city of Ghardaïa via in-situ measurements. The thermal behavior of measurement sites varies between urban heat island and cool island. It was detected an "archipelago" of heat throughout the city. The maximum intensity of UHI is 2.98 ° C. As for the intra-urban differences, the vegetation produces a maximum PCI of 5.61 ° C. The minimum night-time temperature is above 30 ° C, well above the thermal comfort limit. The moderating effect of vegetation is mainly due to the shade provided by tree canopy. Vegetated sites do not show a significant difference in humidity compared to other built-up sites. It seems that a denser urban vegetation cover would further improve comfort conditions in the city.
This paper proposes a contribution to tackle urban sanitation issues giving some hindsight on a place-based science-practice collaborative project. Insights from a French public service in charge of ...On-site Wastewater Treatment Systems (OWTS) highlighted the need to deepen the understanding of soil infiltration assessments and to clarify their relation to some misunderstandings between actors. The initial aim was to explore how a knowledge based approach can offer an original perspective to historical “septic tanks” and overcome technical and organizational difficulties. In this work we consider OWTS as hybrid infrastructures necessary to collect, transport, treat and dispose of domestic wastewater on the plot where it is generated. We suppose that OWTS adaptive management (sludge not included) offer many opportunities regarding water circulation (ecological function), infrastructure diversity (redundancy), and soil-based decision making (spatial planning). The main objective of this paper is to document the French sociotechnical configuration through the interplay between soil and water actors, OWTS technics and local institutions. The originality is to look at OWTS through the lens systemic perspective of Nature-Based Solutions (NBS). We first contextualize OWTS implementation and planning by presenting technical design studies (water-soil interactions, indicators assessment) and the diversity and capacity of actors. Second, we build on the application of a soil-based methodology in a peri-urban district to provide a place-based outlook on the influence of soil infiltration rates variability in day-to-day management. While the current consideration given to soil infiltration rate in OWTS design studies created a situation of conflicts and contestations between actors, a sociotechnical transition is taking place with new regulations and innovative energy-driven device. Moreover, collective infrastructure for domestic wastewater is currently challenged by densification constraints in metropolitan areas (urban sprawl regulation). As a consequence, resolving binding measures for indicators assessment would support OWTS integration into mainstream urban development. Careful investigation of soil hydraulic functions is thus a steppingstone in the search for an adaptive strategy both at the plot and the neighborhood scales. Not only OWTS are opportunities to support the adaptive management process in the water sector, but OWTS have also the potential to improve soil-based decision-making in urban areas. Finally, valuating OWTS as useful NBS for wastewater management in urban areas supports the evaluation of soil capacities to deliver ecosystem services and contributes to justify land-use changes on a functional knowledge basis.
Animals in urban environments face challenging situations and have to cope with human activities. This study investigated the ecology and behaviour of a population of European hamsters (Cricetus ...cricetus) living in the city centre of Vienna (Austria). We recorded the surface activities of 35 hamsters in May 2015. Each focal animal was observed for 15 minutes, and a total of 66 focal samples were analysable. As a prey species in an environment teeming with human activities, we predicted a high level of vigilance by the hamsters. The results show that while animals dedicated a lot of time to vigilance, most of their time was spent foraging. The study also explores whether the frequency of vigilance behaviours differ between males and females. We found that vigilance behaviours were expressed in a different manner by males and females. Finally, we investigated the distribution of the burrows on green spaces depending on proximity to trees and on noise levels. We found a biased distribution of burrows, with a spatial preference for location protected by the vegetation and distant to noise sources. Although burrows were located preferentially under vegetation cover, levels of noise did not determine their positions. Moreover, this species does not respond to disturbances like daily urban noises, probably due to habituation. The common hamster is an endangered species; our results lead to a greater knowledge of its behaviour in a persistent urban population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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