Search results for "Nature"
showing 10 items of 1564 documents
Possible influence of Zoophycos bioturbation on radiocarbon dating and environmental interpretation
2002
Abstract In paleoenvironmental studies of marine sediments bioturbation is often neglected and/or only treated as a diffusion-like process affecting only the uppermost sediment with decreasing intensity with depth. Deep dwelling animals, like the Zoophycos producing animal, however, affect the sediment composition by transporting material over vertical distances of up to 1 m below the seafloor. In Arabian Sea sediment cores 70KL, 64KL and 57KL a significant downward transport of particles by Zoophycos can be observed. Within the Zoophycos burrows the faunal composition of both planktonic and benthic foraminiferal assemblages as well as the isotopic signature of foraminiferal carbonate diffe…
The anthropogenic sealing of soils in urban areas
2009
The sealing of soils by impervious materials is, normally, detrimental to its ecological functions. Exchanges of energy, water and gases are restricted or hampered and an increasing pressure is being exerted on adjacent, non sealed areas. The negative effects span from loss of plant production and natural habitats to increased floods, pollution, and health risks and consequently higher social costs. Environmental Agencies produce periodical reports where the phenomenon of soil consumption by urban infrastructures is monitored with extremely sophisticated geographical tools but little specific research is available that describes the effects of soil sealing. This paper reviews some recent co…
Sex-specific genetic differences in endurance swimming of Trinidadian guppies.
2015
Abstract Swim performance is considered a main fitness‐determining trait in many aquatic organisms. Swimming is generally the only way most aquatic prey can escape predation, and swimming capacity is directly linked to food capture, habitat shifts, and reproduction. Therefore, evolutionary studies of swim performance are important to understand adaptation to aquatic environments. Most studies, however, concentrate on the importance of burst‐swim responses to predators, and little is known about its effect on endurance. Even fewer studies associate differences in organism swim capabilities to key gender‐specific responses. In this experiment, we assess the gender‐specific genetic basis of sw…
Shifts in plankton assemblages promoted by free water surface constructed wetlands and their implications in eutrophication remediation
2015
Abstract Two units of free water surface constructed wetlands (FWSCWs) were created in 2009 in a Mediterranean protected site, the Albufera de Valencia Natural Park, to treat eutrophic inflows to the Albufera de Valencia lagoon, the largest coastal lagoon in the Iberian Peninsula, affected by cultural eutrophication. Data of phytoplankton and zooplankton biomass and richness of the inflows and outflows corresponding to the first 3.5 years of operation of the system have been analyzed to evaluate the role of plankton in the eutrophication reversion. The FWSCWs significantly reduced the exported microalgal biomass, stimulated the potential mixotrophic groups of phytoplankton such as Euglenoph…
The effects of post-pasture woody plant colonization on soil and aboveground litter carbon and nitrogen along a bioclimatic transect.
2013
Abstract: We investigated the effects of woody plant colonization of abandoned pastures on soil and litter organic carbon (C) stocks and nitrogen (N) content along a bioclimatic transect in a semi-arid environment (Sicily, Italy). Soil samples were taken in three successional stages (grazed pasture, shrubland, forest) within each of three bioclimates (supramediterranean - “supra”, mesomediterranean - “meso”, thermomediterranean - “thermo”). Organic C and N in litter and soil (0-10 cm and 10-30 cm depth) were determined, as well as soil bulk density. Especially at 0-10 cm depth, changes in C and N contents along successional stages differed among bioclimates. Soil organic carbon (SOC) stock …
The role of eutrophication reduction of two small man-made Mediterranean lagoons in the context of a broader remediation system: Effects on water qua…
2013
In order to meet the requirements of the European Union Water Framework Directive for the Albufera de Valencia (AV) Natural Park, in 2009, several areas of free water surface constructed wetlands (FWSCWs) planted with emergent vegetation and two small shallow lagoons planted with submerged macrophytes were created over a 40-ha area formerly occupied by rice fields. This area is currently a reserve known as Tancat de la Pipa. The dual goal of this programme was to improve the quality of the hyper-eutrophicated waters of the AV lagoon, the largest littoral lagoon in the Iberian Peninsula, and to restore former lost habitats to increase the biodiversity of the area. The lagoons were mainly fed…
Landslide inventory and rockfall risk assessment of a strategic urban area (Palermo, Sicily)
2019
This study concerns the assessment of the rockfall risk for two strategic sectors of the Mount Pellegrino, one of the most relevant place in the city of Palermo. During the last two decades, several rockfalls affected the study area setting up a serious threat to the people, structures and infrastructures preventing the economic and social development. For these landslides a detailed GIS inventory was realized; the most dangerous rockfalls occurred within the two study sectors. In both areas we have carried out detailed field surveys and the geo-mechanical characterization of the rock slopes. These analyses allowed to define the rock mass parameters, the set of discontinuities and the kinem…
Habitat preference of endangered Eastern Iberian Reed BuntingsEmberiza schoeniclus witherbyi
2011
Capsule Careful management is required to maintain or create habitats with the correct proportions of rush with reeds that are preferred by this subspecies. Aims To determine the habitat requirements of Eastern Iberian (Western Iberian Reed Buntings were not included in the study) Reed Buntings Emberiza schoeniclus witherbyi, a subspecies endemic to a few marshes in France, Spain and Morocco, with a population of 254–360 breeding pairs. Methods Twenty-five wetlands in Spain were surveyed and presence/absence of Iberian Reed Buntings was deteremined together with data on 41 environmental variables. The relationships between the birds and habitat data were investigated using glm. Results Prop…
Conservation value of forest plantations for bird communities in western Kenya
2008
Tree plantations of native and exotic species are frequently used to compensate for forest loss in the tropics. However, these plantations may support lower species diversity and different communities than natural forest. We therefore investigated bird communities in stands of natural forest, different types of tree plantations and secondary forest in Kakamega Forest, western Kenya. We compared birds differing in habitat specialisation, i.e. forest specialists, generalists, and visitors. We recorded significant differences in mean species richness and number of individuals among the different forest types. Stands of natural forest and plantations of indigenous tree species comprised more sp…
High seedling recruitment of indigenous tree species in forest plantations in Kakamega Forest, western Kenya
2009
Tree plantations are often used to compensate for the destruction and conversion of natural forests in the tropics. An important question is whether these plantations allow for the regeneration of indigenous tree species and are expected to transform into more natural forests in the future. To evaluate the potential of differently managed forest types for seedling recruitment of indigenous tree species we studied structural characteristics as well as tree and seedling communities in stands of natural forest, different types of tree plantations and secondary forest in Kakamega Forest, western Kenya. Forest types differed considerably in structural characteristics and tree composition with st…