Search results for "SCALE"
showing 10 items of 5180 documents
Chronostratigraphy and geochronology: A proposed realignment.
2013
We propose a realignment of the terms geochronology and chronostratigraphy that brings them broadly into line with current use, while simultaneously resolving the debate over whether the Geological Time Scale should have a “single” or “dual” hierarchy of units: Both parallel sets of units are retained, although there remains the option to adopt either a single (i.e., geochronological) or a dual hierarchy in particular studies, as considered appropriate. Thus, geochronology expresses the timing or age of events (depositional, diagenetic, biotic, climatic, tectonic, magmatic) in Earth’s history (e.g., Hirnantian glaciation, Famennian-Frasnian mass extinction). Geochronology can also qualify r…
Geology of Monte Gallo (Palermo Mts, NW Sicily)
2016
The promontory of Monte Gallo (Palermo, NW Sicily) is a spectacular site where Upper Triassic-Eocene carbonate platform rocks and Quaternary continental to marine deposits are well exposed. A Mesozoic-Paleogene rock succession allows the potential visitor to easily detect the features and the evolution of the Panormide carbonate platform, a shallow-water paleogeographic domain of the Southern Tethyan margin. Quaternary deposits, as well many landforms, enable the visitor to directly identify the interplay between climate changes, tectonics and fluctuations of marine level that occurred during the Quaternary Period. A detailed geological map (1:15,000 mapping scale) is presented, accompanied…
Tree-ring δ2H values from lignin methoxyl groups indicate sensitivity to European-scale temperature changes
2020
Abstract Stable hydrogen isotope ratios of lignin methoxyl groups (δ2HLM) of wood have been shown to reflect climate-sensitive δ2H values of precipitation (δ2Hprecip). However, a detailed calibration study between high-resolution δ2HLM and δ2Hprecip data has not been performed yet. Here, we present annually resolved δ2HLM values from nine tree-ring series (derived from four Fagus sylvatica L. trees) collected near a station of the Global Isotope Network of Isotopes in Precipitation (GNIP) and the meteorological observatory at Hohenpeisenberg (Germany; ~48°N, 11°E). The nine δ2HLM tree-ring series show highly significant inter-series correlations (Rbar = 0.52) over the common period of overl…
More is more? : Forest management allocation at different spatial scales to mitigate conflicts between ecosystem services
2017
Context: Multi-objective management can mitigate conflicts among land-use objectives. However, the effectiveness of a multi-objective solution depends on the spatial scale at which land-use is optimized. This is because the ecological variation within the planning region influences the potential for site-specific prioritization according to the different objectives. Objectives: We optimized the allocation of forest management strategies to maximize the joint production of two conflicting objectives, timber production and carbon storage, at increasing spatial scales. We examined the impacts of the extent of the planning region on the severity of the conflict, the potential for its mitigation…
Gauging scale effects and biogeographical signals in similarity distance decay analyses: an Early Jurassic ammonite case study.
2016
17 pages; International audience; In biogeography, the similarity distance decay (SDD) relationship refers to the decrease in compositional similarity between communities with geographical distance. Although representing one of the most widely used relationships in biogeography, a review of the literature reveals that: (1) SDD is influenced by both spatial extent and sample size; (2) the potential effect of the phylogenetic level has yet to be tested; (3) the effect of a marked biogeographical structuring upon SDD patterns is largely unknown; and (4) the SDD relationship is usually explored with modern, mainly terrestrial organisms, whereas fossil taxa are seldom used in that perspective. U…
Biodiversity is not (and never has been) a bed of roses!
2011
9 pages; International audience; Over the last decades, the critical study of fossil diversity has led to significant advances in the knowledge of global macroevolutionary patterns of biodiversity. The deep-time history of life on Earth results from background originations and extinctions defining a steady-state, nonstationary equilibrium occasionally perturbed by biotic crises and "explosive" diversifications. More recently, a macroecological approach to the large-scale distribution of extant biodiversity offered new, stimulating perspectives on old theoretical questions and current practical problems in conservation biology. However, time and space are practically distinct, but functional…
Tendencies in paleontological practice when defining species, and consequences on biodiversity studies
2005
The exploration of evolutionary patterns over geological time has recently received new impetus from the development of morphological disparity as a new biodiversity metric alongside taxonomic diversity. Clade dynamics can be analyzed by comparing and contrasting these two metrics. Like any metrics based on sampling, quantification, and naming, taxonomic diversity and morphological disparity are not free from bias. The long use of taxonomic diversity has prompted many studies of bias and its effects, whereas bias affecting morphological disparity has only been summarily explored. This is particularly so for the effect of the growth of knowledge over paleontographical time (i.e., historical …
Give me a sample of air and I will tell which species are found from your region : Molecular identification of fungi from airborne spore samples
2017
Fungi are a megadiverse group of organisms, they play major roles in ecosystem functioning and are important for human health, food production and nature conservation. Our knowledge on fungal diversity and fungal ecology is however still very limited, in part because surveying and identifying fungi is time demanding and requires expert knowledge. We present a method that allows anyone to generate a list of fungal species likely to occur in a region of interest, with minimal effort and without requiring taxonomical expertise. The method consists of using a cyclone sampler to acquire fungal spores directly from the air to an Eppendorf tube, and applying DNA barcoding with probabilistic specie…
Through the eye of a lizard: hue discrimination in a lizard with ventral polymorphic coloration.
2017
Colour polymorphisms are thought to be maintained by complex evolutionary processes some of which require that the colours of the alternative morphs function as chromatic signals to conspecifics. Unfortunately, a key aspect of this hypothesis has rarely been studied: whether the study species perceives its own colour variation as discrete rather than continuous. The European common wall lizard (Podarcis muralis) presents a striking colour polymorphism: the ventral surface of adults of both sexes may be coloured orange, white, yellow, or with a mosaic of scales combining two colours (orange-white, orange-yellow). Here we use a discrimination learning paradigm to test if P. muralis is capable…
Effects of the temporal scale of observation on the analysis of aquatic invertebrate metacommunities
2020
The development of metacommunity theory has boosted the implementation of numerous empirical tests with field data, mostly focused on the role of spatial and environmental gradients on metacommunity organization. These studies showed an important dependence of the results on the observational scale considered, i.e., spatial grain, sampling spacing, and extent. However, few works deal with time per se as a component explaining metacommunity structure, even when data from periodic sampling are available. We suggest adding time explicitly to metacommunity analysis, but taking into account that the temporal scale of observation could affect the estimation of the relative influence of environmen…