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showing 10 items of 20402 documents
Climate change fosters the decline of epiphytic Lobaria species in Italy
2016
Similarly to other Mediterranean regions, Italy is expected to experience dramatic climatic changes in the coming decades. Do to their poikilohydric nature, lichens are among the most sensitive organisms to climate change and species requiring temperate-humid conditions may rapidly decline in Italy, such in the case of the epiphytic Lobaria species that are confined to humid forests. Our study, based on ecological niche modelling of occurrence data of three Lobaria species, revealed that in the next decades climate change will impact their distribution range across Italy, predicting a steep gradient of increasing range loss across time slices. Lobaria species are therefore facing a high ext…
Factors affecting population dynamics of Eurasian woodcocks wintering in France: assessing the efficiency of a hunting-free reserve
2005
International audience; The Eurasian woodcock Scolopax rusticola is a migratory bird of major importance for hunting, which is susceptible to habitat loss and the stochastic effects of severe winter weather. Conservation issues mostly concerned regulation of hunting, but the efficiency of hunting-free reserves has never been investigated. We studied causes of mortality and survival probabilities of 98 radio-tagged woodcocks in a reserve with no hunting and in an adjoining hunting area in Brittany (France). Predation, mostly by mammalian predators on fields at night, was similar among adults and yearlings, while hunting mortality was more important in yearlings. Overall winter survival proba…
Ectosymbiosis is a critical factor in the local benthic biodiversity of the Antarctic deep sea.
2008
10 pages; International audience; In deep-sea benthic environments, competition for hard substrates is a critical factor in the distribution and diversity of organisms. In this context, the occurrence of biotic substrates in addition to mineral substrates may change the characteristics of sessile fauna. We tested this hypothesis at different localities of the Weddell Sea (Antarctica) by studying the diversity of ectosymbionts living on the spines of cidaroids (echinoids). The presence of cidaroids promoted a higher total specific richness and increased sessile species abundance, but did not change the diversity. Analyses of species distribution suggested that the cidaroids are a favourable …
Developing an orientation and cutting point determination algorithm for a trout fish processing system using machine vision
2019
Abstract Fish processing in small and medium fish supplying centers requires an intelligent system to operate on different sizes. Therefore, an image processing algorithm was developed to extract the proper head and belly cutting points according to the trout dimensions. The algorithm detects the fish orientation and location of pectoral, anal, pelvic, and caudal fins. In this study, each of the trout images was divided into slices along its length in order to segment the fins and extract cutting points. The channel ‘B’ of RGB color space was considered in both initial segmentation and fin detection stages among the examined channels of RGB, HSV, and L*a*b* color spaces. The back-belly and …
Fragmentation-related patterns of genetic differentiation in pedunculate oak (<i>Quercus robur</i>) at two hierarchical scales
2016
Populations at speciesâ range margins are expected to show lower genetic diversity than populations at the core of the range. Yet, long-lived, widespread tree species are expected to be resistant to genetic impoverishment, thus showing comparatively high genetic diversity within populations and low differentiation among populations. Here, we study the distribution of genetic variation in the pedunculate oak ( L.) at its range margin in Finland at two hierarchical scales using 15 microsatellite loci. At a regional scale, we compared variation within versus among three oak populations. At a landscape scale, we examined genetic structuring within one of these populations, growing on an islan…
Oxygen transmittance correction for solar-induced chlorophyll fluorescence measured on proximal sensing: Application to the NASA-GSFC fusion tower
2017
Since oxygen (O 2 ) absorption of light becomes more pronounced at higher pressure levels, even a few meters distance between the target and the sensor can strongly affect canopy-leaving Solar-Induced chlorophyll Fluorescence (SIF) retrievals. This study was conducted to quantify the consequent error propagation and the impact of ignoring oxygen absorption effects on proximal sensing SIF measurements based on the O 2 -A absorption band with field-acquired and simulated data. It was demonstrated that the uncorrected oxygen transmittance between target and sensor distance of 10 m can lead to SIF relative errors ranging from 66% to higher than 100% when using a Spectral Fitting (SF) technique …
Incorporating Biotic Information in Species Distribution Models: A Coregionalized Approach
2021
In this work, we discuss the use of a methodological approach for modelling spatial relationships among species by means of a Bayesian spatial coregionalized model. Inference and prediction is performed using the integrated nested Laplace approximation methodology to reduce the computational burden. We illustrate the performance of the coregionalized model in species interaction scenarios using both simulated and real data. The simulation demonstrates the better predictive performance of the coregionalized model with respect to the univariate models. The case study focus on the spatial distribution of a prey species, the European anchovy (Engraulis encrasicolus), and one of its predator spe…
Tracking management-related water quality alterations by phytoplankton assemblages in a tropical reservoir
2015
Water quality improvement and suppression of cyanobacterial blooms were planned in a eutrophic reservoir in southern China through ecological engineering measures from 2006 to 2011. This consisted in (i) a hydraulic resetting of inflows and outflows to increase the distance between inlet and outlet and the water residence time in the reservoir, and in (ii) the installation of floating frames hosting wetland vegetation to promote an alteration in phytoplankton composition. The environmental changes were therefore followed through the analysis of biotic responses in phytoplankton assemblages. Ecological engineering was effective in reducing phytoplankton total biomass, in re-establishing more…
Distance decay 2.0 – a global synthesis of taxonomic and functional turnover in ecological communities
2021
AbstractUnderstanding the variation in community composition and species abundances, i.e., β-diversity, is at the heart of community ecology. A common approach to examine β-diversity is to evaluate directional turnover in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distances. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 149 datasets comprising different types of organisms and environments. We modelled an exponential distance decay for each dataset using generalized linear models and extracted r2 and slope to analyse the streng…
Linking species interactions with phylogenetic and functional distance in European bird assemblages at broad spatial scales
2017
Aim Understanding the relative contribution of different species interactions in shaping community assembly has been a pivotal aim in community ecology. Biotic interactions are acknowledged to be important at local scales, although their signal is assumed to weaken over longer distances. We examine the relationship between positive, neutral and negative pairwise bird abundance distributions and the phylogenetic and functional distance between these pairs after first controlling for habitat associations. Location France and Finland. Time period 1984 to 2011 (Finland), 2001 to 2012 (France). Major Taxa studied Birds. Methods We used results from French and Finnish land bird monitoring program…