Search results for "VEGETATION"
showing 10 items of 1069 documents
Timing and patterns of the ENSO signal in Africa over the last 30 years: insights from normalized difference vegetation index data.
2014
Abstract A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact of ENSO on vegetation dynamics as a combined result of ENSO on rainfall, solar radiation, and temperature. The month-by-month NDVI–Niño-3.4 correlation patterns evolve as follows. From July to September, negative correlations are observed over the Sahel, the Gulf of Guinea coast, and regions from the northern Democratic Republic of Congo…
Restoration of two small Mediterranean lagoons: The dynamics of submerged macrophytes and factors that affect the success of revegetation
2013
Abstract Two small, shallow lagoons newly created from former rice fields in the Mediterranean coast (Albufera de Valencia Natural Park, Spain) were restored by planting several species of submerged macrophytes (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton spp., Zannichellia peltata and Ranunculus peltatus) in 2008. Charophytes also appeared spontaneously. M. spicatum was the species that dominated both lagoons and almost completely covered their surface. M. spicatum reached a high biomass and displayed a seasonal pattern, declining during the cold season and reappearing in the spring. No submerged vegetation was observed in the lagoons from 2011 onward. The major purpose of t…
Vegetation, soils, and humus forms of Sardinian holm oak forests and approximated cross-harmonization of vegetation types, WRB Soil Groups and humus …
2018
Five plant communities, related to elevation above sea level and geological substrata, are recognized in the holm oak forests of Sardinia (Italy). These forests show a considerable inhomogeneous structure due to present day and past uses. Coppice management prevails, influencing the quantity and quality of organic horizons. Most frequent mineral soils are Cambisols, Leptosols, and Regosols. Regarding the humus forms, Moder and, with less extent, Amphi, are prevailing. Furthermore, the paper presents a synoptic table giving a rough picture of the relationships between vegetation types, WRB Soil Groups and humus forms in selected Mediterranean ecosystems.
The First Forty Years of a Technosol
2009
Abstract Soil formation is often a very slow process that requires thousands and even millions of years. Human influence, occasionally on a par with the function of climate or geological forces, can accelerate the process and can be viewed as a distinct soil forming factor. This paper describes a soil, Haplic Regosol, in which anthrosolization dominates the soil forming process. Man-made soils, Technosols, were stabilized with techniques of ecological engineering (crib walls). We measured the main soil properties and focused on the movement of water (the reduction of soil weight is the key factor in stabilizing these calcschists). The newly deposited debris, sheltered by anthropic intervent…
Advances in the Retrieval and Interpretation of Solar-Induced Vegetation Chlorophyll Fluorescence Using Passive Remote Sensing Techniques
2021
In the context of the development and implementation of the Fluorescence Explorer (FLEX) mission, selected in 2015 by the European Space Agency (ESA) as the 8th Earth Explorer, many recent developments in the field of vegetation chlorophyll fluorescence have taken place in the last years. These advances include new retrieval approaches, more accurate and robust, and a much better understanding of the variability of the signal, facilitating the interpretation of the dynamical changes and the usage of the fluorescence signal in Earth models and applications. Although chlorophyll fluorescence is related to the actual photosynthetic activity of the plants, the link between fluorescence and phot…
Phytosociological and phytogeographical considerations on the orophilous alliance Berberido aetnensis-Crataegion laciniatae (Rhamno-Prunetea)
2011
Malaria resurgence risk in southern Europe: climate assessment in an historically endemic area of rice fields at the Mediterranean shore of Spain
2010
Abstract Background International travel and immigration have been related with an increase of imported malaria cases. This fact and climate change, prolonging the period favouring vector development, require an analysis of the malaria transmission resurgence risk in areas of southern Europe. Such a study is made for the first time in Spain. The Ebro Delta historically endemic area was selected due to its rice field landscape, the presence of only one vector, Anopheles atroparvus, with densities similar to those it presented when malaria was present, in a situation which pronouncedly differs from already assessed potential resurgence areas in other Mediterranean countries, such as France an…
Investigating the Performance of Enhanced Permeable Groins in Series
2020
The enhanced permeable groin is a novel eco-friendly and cost-effective technique for bank protection and restoration of meander bends. The behavior of bed deformations due to the distance between the structures has to be studied to design enhanced permeable groins in series properly. In this study, scour morphologies around enhanced permeable groins in series, characterized by four different distances and located in a 180°
Flow velocity profile and turbulence characteristics in a vegetated straight flume
2008
Vegetation affects the hydrodynamic conditions of an open channel flow with direct implications in physical and biophysical processes. In this paper, the vertical flow velocity distribution of a vegetated flow has been analyzed using experimental data collected in a straight flume. The experimental velocity distributions are positively compared with the hyperbolic tangent profile of a pure mixing layer previously verified by Ghisalberti and Nepf (2002). Peculiarly, for different flow and vegetative conditions, fitting of the hyperbolic tangent profile to the experimental velocity distributions has allowed the localization of the inflection point of the velocity profile at a distance from th…
Vegetation against erosion downstream of a hydraulic structure
2016
The present work shows the effects of vegetation on sediment transport process. The volume of sediments transported at different time steps is determined by applying a numerical model previously developed [4] and the model parameters are calibrated by using the experimental data.