Search results for " Ecosystem"
showing 10 items of 633 documents
Dynamics of closed ecosystems described by operators
2014
Abstract We adopt the so-called occupation number representation , originally used in quantum mechanics and recently adopted in the description of several classical systems, in the analysis of the dynamics of some models of closed ecosystems. In particular, we discuss two linear models, for which the solution can be found analytically, and a nonlinear system, for which we produce numerical results. We also discuss how a dissipative effect could be effectively implemented in the model.
Parameter Sensitivity and the Quality of Model Predictions
1994
Using SIM-PEL, a comprehensive model for the pelagic compartment of lake ecosystems, we analyse synergistic toxicant effects in lake ecosystems. We show, that — even for a rather simple model — model predictions may be strongly dependent on the time horizon of the prediction and on the quality of input parameters. For longer time spans, small errors in parameter estimation may lead to qualitatively wrong prediction of toxicant effects. Monte Carlo simulations allow to take errors in parameter estimation into account, but they need rather good estimates of parameter variance.
Anthropic space and design for all. New knowledge paths for urban planning strategies
2019
Abstract Nowadays city environment shows the presence of a mixed variety of elements, as natural, semi natural and anthropic components that build up both structure and connections of the urban context. This specific structure shapes and directs space and its functions strictly connected with their sustainable potential uses and sustainable development opportunities. The lack of rules and proper planning methods produces inefficient use conditions by resident citizens, entropy, functions' reduction of ecological networks and deep environmental impacts. The consequence comes out to be a great widespread life quality decrease in urban areas. These thoughts lead the authors to rethink the defi…
Evaluation of approaches for measuring taxonomic completeness of lake profundal macroinvertebrate assemblages
2011
Summary 1. Benthic macroinvertebrates (MI) are commonly used to assess freshwater ecosystems with the reference condition approach. Such assessments necessitate control for natural community variation, either by categorical typologies or by predictive models that have been widely and successfully developed for running water biota but not previously for lake profundal invertebrates. 2. We evaluated four modelling techniques [multivariate regression tree (MRT), limiting environmental differences, nonparametric multiplicative regression (NPMR) and River Invertebrate Prediction And Classification System (RIVPACS) and the operative Finnish lake typology for assessing taxonomic completeness (obse…
Accumulation and discharge behavior of Cs-137 by zebra fish (Brachydanio rerio) in different aquatic environments
1990
The uptake and release kinetics of137Cs from water by the tropical fishBrachydanio rerio has been studied under controlled laboratory condition. The accumulation of this radionuclide from food was avoided by feeding the fishes separately in an inactive environment. A steep inverse dependence of bioconcentration factor (BCF) with potassium concentration has been observed. This can formally be described by the equation BCF=5.2 · [K+]−0.44. The elimination rate constant K in fresh water conditions has been found to have a magnitude of 0.014±0.03 d−1 which corresponds to a biological half-life of 51±10 days. The uptake and release kinetics ofBrachydanio rerio has been compared with earlier stud…
Early Cambrian origin of modern food webs: evidence from predator arrow worms.
2007
7 pages; International audience; Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cam…
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.
Remote Sensing for Agriculture, Ecosystems, and Hydrology XX
2018
This proceedings volume contains papers presented during the Remote Sensing for Agriculture, Ecosystems, and Hydrology Conference. The Conference was part of the International Symposium on Remote Sensing sponsored by SPIE—The International Society for Optics and Photonics. The Symposium was held at the ESTREL Congress Centre, Berlin, Germany, from 10th to 13th of September 2018. Approximately 40+ oral and 20 poster papers were presented during this year’s conference, covering a broad range of topics in the field of remote sensing applications for environmental science.
Quality of Lake Ecosystems and its Role in the Spread of Invasive Species
2021
Abstract Lake ecosystems are important elements of hydrological regime, the quality of these ecosystems is affected by anthropogenic actions, and therefore, a variety of organisms, living in these habitats depend on the applied management solutions. Due to human activities freshwater ecosystems suffer from loss of biodiversity and increased eutrophication. Therefore, important aspects related to lake management include knowledge about the water quality, ecosystem response to climate change as well as increased risks of appearance and spreading of invasive species. Water quality, content of oxygen, nutrients, phytoplankton and distribution of macrophytes, including invasive species were anal…
A methodological approach for assessing businness investments in renewable resources from a circular economy perspective
2018
Abstract In this paper, we have analyzed a feasibility project for the realization of a biogas plant at a company in the viticulture sector located in south-central Sicily. Using engineering formulas, we identified the electrical power that the plant could produce using waste products created by the vineyard itself, examined the new and interesting opportunities that have arisen with the encouragement and development of biogas production in Italy, and then assessed the economic feasibility of the investment itself, considering an investment scheme of total capital self-financing. The possibility of using wastes from wine production comes from an in-depth study of the circular economy, that …