Search results for "VEGETATION"
showing 10 items of 1069 documents
Public and Private Economic Feasibility of Green Areas as a Passive Energy Measure: A Case Study in the Mediterranean City of Trapani in Southern Ita…
2022
Green infrastructure in urban environments provides a wide range of ecological, social, aesthetic, and health co-benefits. Urban plant covers in particular contribute to improved outdoor environmental conditions that, in turn, influence the energy behavior of buildings and their indoor thermo-hygrometric comfort performance. Within this context, this study illustrates a methodology aimed at verifying the economic feasibility of alternative types of green areas for public and private stakeholders, which are analyzed as passive energy measures. Therefore, our methodology integrates approaches from different disciplines and consists of a microclimatic analysis of different vegetation scenarios…
Urban Heat Island (UHI) and heat waves: what relations?
2018
With four years of measurements and alarge sample of stations, the MUSTARDijon network allows for a detailed characterization of the Urban HeatIsland (UHI), a warm season phenomenon. But UHI and maximum temperature values are out of phase at twodistinct time-scales. Seasonally, the maxima of UHI occur from May to July, i.e. before the annual peak oftemperature (July to August). At a daily time-scale, analysis of the two heat waves of July 2015 shows a lag of afew days between the peak of UHI and the heat wave. Two hypotheses are suggested to explain these lags:changes in radiative conditions and/or energy fluxes between the ground surface and the atmosphere.
Modeling the hydrological and mechanical effect of roots in shallow landslide analysis
2015
The additional cohesion exercised by vegetation roots (cr) provides an important contribution to the slope stability. This study proposes a methodology for estimating the cr term in a hillslope landslide analysis within a coupled ecohydrological-stability model. The coupled model simulates the spatial distribution and temporal dynamics of the Factor of Safety (FS) as a function of soil moisture dynamics, by taking into account the hydrological effects of vegetation through the root water uptaking. The additional mechanical root cohesion is estimated in a Fiber Bundle Model framework that allows for the evaluation of the root strength as a function of stress-strain relationships of populatio…
Hydrological and mechanical effects of roots in shallow landslide analysis: A physically-based approach
2015
This study provides the first insights of a methodology for estimating the additional cohesion exercised by vegetation roots in a hillslope landslide analysis within a coupled ecohydrological-stability model. The existing coupled system is able to simulate the spatial distribution and temporal dynamics of Factor of Safety (FS) as a function of soil moisture dynamics. The model takes into account the hydrological effects of vegetation which, through the root water uptaking, contributes in reducing the soil water content and, thus, in increasing the slope stability. The additional mechanical root cohesion is estimated in a Fiber Bundle Model (FBM) framework that allows for the evaluation of t…
Hydrophytic vegetation aspects in the Nebrodi mountains (Sicily)
2009
The vegetation of damp areas in the Nebrodi Natural Park was already surveyed in some studies (Brullo et al. 1994). In particular, the various hygro and hydrophytic aspects were referred to associations belonging to the Phragmitetea and the Potamogetonetea classes respectively. Small lacustrine habitats in Sicily have disappeared almost everywhere and are conserved still today only in the Nebrodi Mountains. They host widely distributed hydrophytes. Some of these plants are rather localized in Sicily, e.g. Potamogeton polygonifolius Pourr. and Utricularia australis R. Br. The latter occurs also in the Madonie Mountains. Recent analyses revealed some hollows characterized by an accentuated re…
Pattern formation in hyperbolic reaction-transport systems and applications to dryland ecology
2023
Pattern formation and modulation is an active branch of mathematics, not only from the perspective of fundamental theory but also for its huge applications in many fields of physics, ecology, chemistry, biology, and other sciences. In this thesis, the occurrence of Turing and wave instabilities, giving rise to stationary and oscillatory patterns, respectively, is theoretically investigated by means of two-compartment reaction-transport hyperbolic systems. The goal is to elucidate the role of inertial times, which are introduced in hyperbolic models to account for the finite-time propagation of disturbances, in stationary and transient dynamics, in supercritical and subcritical regimes. In p…
The classification of submerged vegetation using hyperspectral MIVIS data
2009
The aim of this research is to use hyperspectral MIVIS data to map the Posidonia oceanica prairies in a coastal lagoon (Stagnone di Marsala). It is approximately 12 km long and 2 km wide and is linked to the open sea by two shallow openings. This environment is characterised by prairies of phanerogams, the most common of which is Posidonia oceanica, an ideal habitat for numerous species of fish, molluscs and crustaceans. A knowledge of the distribution of submerged vegetation is useful to monitor the health of the lagoon. In order to classify the MIVIS imagery, the attenuation effects of the water column have been removed from the signal using Lyzenga’s technique. A comparison between class…
Angular Dependency of Hyperspectral Measurements over Wheat Characterized by a Novel UAV Based Goniometer
2015
In this study we present a hyperspectral flying goniometer system, based on a rotary-wing unmanned aerial vehicle (UAV) equipped with a spectrometer mounted on an active gimbal. We show that this approach may be used to collect multiangular hyperspectral data over vegetated environments. The pointing and positioning accuracy are assessed using structure from motion and vary from σ = 1° to 8° in pointing and σ = 0.7 to 0.8 m in positioning. We use a wheat dataset to investigate the influence of angular effects on the NDVI, TCARI and REIP vegetation indices. Angular effects caused significant variations on the indices: NDVI = 0.83–0.95; TCARI = 0.04–0.116; REIP = 729–735 nm. Our analysis high…
Micro-scale post-fire surface cover changes monitored using high spatial resolution photography in a semiarid environment: A useful tool in the study…
2012
[ES] Although post-fire soil erosion has been studied, little attention has been paid to changes in soil surface cover following fires, despite this being a key factor in understanding the water and sediment yield. This study, at Peñaflor (Spain), investigated the effect of fire on soil erosion using data from soil erosion plots and high spatial resolution photography (HSRP). Measurements were made from October 2003 to October 2005 in a control plot and a plot experimentally exposed to a fire in October 2004. Ground cover components were identified, including vegetation, bare soil, stones, charcoal and ash. Runoff and sediment concentrations were low because of the absence of intense rainfa…
Camouflage in arid environments: the case of Sahara-Sahel desert rodents
2020
Deserts and semi-deserts, such as the Sahara-Sahel region in North Africa, are exposed environments with restricted vegetation coverage. Due to limited physical surface structures, these open areas provide a promising ecosystem to understand selection for crypsis. Here, we review knowledge on camouflage adaptation in the Sahara-Sahel rodent community, which represents one of the best documented cases of phenotype-environment convergence comprising a marked taxonomic diversity. Through their evolutionary history, several rodent species from the Sahara-Sahel have repeatedly evolved an accurate background matching against visually-guided predators. Top-down selection by predators is therefore …