Search results for "VEGETATION"
showing 10 items of 1069 documents
A comparison of two methods for surveying aquatic macrophyte communities in boreal lakes: Implications for bioassessment
2013
To compare the performance of two common methods for surveying boreal lake aquatic macrophyte communities (the transect survey and the phytolittoral inventory) in lake bioassessment, we studied five small humic lakes with both methods. In addition to this pairwise comparison, we contrasted available independent sets of reference lake data of either methodological origin. Specifically, we compared the observed species richness and a number of ecological quality (community) metrics and their variability both between the methods and within them in relation to sampling effort and operator. With the phytolittoral inventory, more taxa (mean 38.8 ± s.d. 12.1) were observed than with transect surve…
The last glacial/interglacial record of rodent remains from the Gigny karst sequence in the French Jura used for palaeoclimatic and palaeoecological …
1995
Abstract A multidisciplinary approach has produced an exceptional chronological log of climatic patterns for the Upper Pleistocene sequence of Gigny Cave (Jura, France) covering the Pre-Eemian, Eemian Interglacial, Middle Glacial and Upper Pleniglacial, as well as a part of the Holocene. Multivariate analysis (correspondence and component analysis) of rodent associations from the sequence is used here to characterize the different climatic stages in terms of relative temperature, plant cover and moisture. Faunal analysis establishes: (1) positive and negative correlations among the variations of the different species; (2) the significance of axis 1 (component analysis) which, in terms of te…
Ecological Indicator Values of Europe (EIVE) 1.0: A Powerful Open-Access Tool for Vegetation Scientists
2016
International audience; Background: Ecological indicator values (EIVs) have a long tradition in vegetation ecological research in Europe. EIVs characterise the ecological optimum of species along major environmental gradients using ordinal scales. Calculating mean indicator values per plot is an effective way of bioindication. Following first systems in Russia and Central Europe, about two dozen EIV systems have been published for various parts of Europe.Aims: As there was no EIV system available at European scale that could be used for broad- scale analyses, e.g. in the context of the European Vegetation Archive (EVA), we develop such a system for the first time for the vascular plants of …
Improvement of the thermal emissivity calculated with the vegetation cover method by using optical atmospherically corrected images
2007
In this paper we assess the influence caused by the lack of atmospheric correction of the optical images used to calculate land surface emissivity (LSE). When thermal emissivity is determined by the Vegetation Cover Method (VCM), information from the solar spectrum in order to calculate the vegetation cover fraction is required. The atmospheric correction is performed in this research by using the combination of the Dark Dense Vegetation method (DDV) and the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) code. The methodology was applied to a Landsat TM image of Tomelloso, Spain. It was determined that the emissivity between 10 and 12 mum only increases 0.4% (which rep…
Modeling transpiration and leaf temperature of urban trees – A case study evaluating the microclimate model ENVI-met against measurement data
2018
Abstract Increasing vegetation cover in cities is a key approach to mitigating urban heat excess. However, both the effect of vegetation on microclimate and the plants’ vitality need to be assessed to support and quantify the effects of such strategies. One way to assess the interactions between vegetation and the urban environment is through microclimate models that can simulate the effects of vegetation onto the urban microclimate as well as effects of urban environments onto vegetation. To provide reliable estimates microclimate models need to be parameterized based on empirically obtained data. In this paper we compare modeled transpiration rates and leaf temperatures of a leading micro…
Comparison Between Fractional Vegetation Cover Retrievals from Vegetation Indices and Spectral Mixture Analysis: Case Study of PROBA/CHRIS Data Over …
2009
Abstract: In this paper we compare two different methodologies for Fractional Vegetation Cover (FVC) retrieval from Compact High Resolution Imaging Spectrometer (CHRIS) data onboard the European Space Agency (ESA) Project for On-Board Autonomy (PROBA) platform. The first methodology is based on empirical approaches using Vegetation Indices (VIs), in particular the Normalized Difference Vegetation Index (NDVI) and the Variable Atmospherically Resistant Index (VARI). The second methodology is based on the Spectral Mixture Analysis (SMA) technique, in which a Linear Spectral Unmixing model has been considered in order to retrieve the abundance of the different constituent materials within pixe…
Linear spectral mixture modelling to estimate vegetation amount from optical spectral data
1996
Abstract Spectral mixture modelling has developed in recent years as a suitable remote sensing tool for analysing the biophysical and compositional character of ground surfaces. In this paper the potentiality of the linear spectral mixture model to extract vegetation related parameters from 0·4-2·5 μm reflectance data has been tested. High spectral resolution reflectance measurements of soil-plant mixtures with different soil colour and plant densities were carried out in a laboratory experiment. The constrained least-squares and the factor analysis unmixing procedures were applied to generate endmember fractions of the components present in the mixtures and to test the validity of the mode…
Vegetation and Thermal comfort in temperate areas: proposal of an integrated methodology for urban and building retrofit
2014
The paper points out the main outcomes of a doctoral research carried out at the Department of Architecture of the University of Palermo, aimed at investigating the issues of environmental, social and economic sustainability related to the recovery of the existing building stock with focus on social housing. In particular, starting from the analysis carried out on a real case of the city of Palermo, through the use of specific simulation tools, the research provides a new methodology for the design and the assessment of the effectiveness of plants and Building-Integrated Vegetation systems used as a cost-effective solutions for urban and building retrofit, contributing to new knowledge and …
Vegetation and soil – related parameters for computing solar radiation exchanges within green roofs: Are the available values adequate for an easy mo…
2016
Several studies analyze the thermal performance of vegetated roofs, presenting either mathematical models or experimental quantifications of heat transfer process through them, also showing the effect of vegetation and soil parameters on the thermal and energy performance of this type of roofing system. However, presently the level of availability of these parameters, has not been enough considered. This work intends to investigate this underestimated issue of the green roofs’ thermal modeling, through the consideration of the availability of parameters pertinent to the shortwave radiation exchange, which are adopted by models based on leaf area index (LAI) and on the fractional vegetation …
First results of iButton® loggers and infrared camera application inside a greenhouse
2017
Greenhouse microclimate management (temperature, relative humidity) plays a very important role in order to optimize the production process improving pest and disease control, irrigation and energy efficiency. The systems mostly used in Sicily (south Italy) to record the ambient parameters are made up of fixed measuring stations able to give useful information about the climate inside the greenhouse limited to some pre-fixed points. In this study we texted a novel system made up of humidity and temperature data loggers (iButton®) placed inside a greenhouse. The iButton® temperature/humidity logger (DS1923) is a rugged, self-sufficient system that measures temperature and/or humidity and r…