A quantitative assessment of the ecological value of sycamore maple habitats in the French Alps

La naturalité est un critère important pour l'évaluation de mesures conservatoires des écosystèmes. Au niveau local, une telle évaluation doit être basée sur des indicateurs objectifs et quantifiables sur le terrain. Dans cette étude, nous avons utilisé une méthode multicritères basée sur la différence entre Valeur Naturelle (NV) et Valeur Conservatoire (CV) pour quantifier la valeur écologique des érablaies de versant à érable sycomore (Acer pseudoplatanus L.) par comparaison avec les peuplements mixtes de hêtraie-sapinière-pessière avoisinants. En effet, les naturalistes ainsi que l'Union Européenne considèrent que les érablaies de versant ont une valeur de conservation et de naturalité élevée. Nos résultats montrent que les valeurs naturelle et de conservation sont significativement plus élevées pour l'érablaie que pour la forêt mixte avoisinante et que cette évaluation ne dépend pas de facteurs abiotiques tels que l'altitude ou l'exposition. En fait, la naturalité de structure et de composition des érablaies de versant sont plus fortes que celles des forêts mixtes et permettent de différencier les deux habitats en termes de valeur écologique. Les gestionnaires peuvent facilement utiliser cette méthode pour évaluer la valeur écologique de petits habitats en zone de montagne, ce qui permet d'établir des orientations sylvicoles pour une gestion conservatoire et proche de la nature. / Naturalness is an important criterion in nature conservation assessment. At the stand-level, such assessment must be based on objective and quantifiable indicators measurable in the field. In this study, we used a multi-criterion method based on the difference between a Natural Value(NV) and a Conservation Value (CV) to quantify the ecological value of sycamore maple patches compared to the surrounding mixed forests. Indeed, sycamore habitats are considered of high natural and conservation value both by naturalists and by European institutions. Our results showed that the natural and conservation values were significantly higher for the sycamore forests than for the surrounding mixed forests and that this assessment did not depend on abiotic factors such as elevation or aspect. Actually, naturalness of structure and composition in the sycamore habitats was higher than for mixed forests and allowed us to differentiate between the two habitats. Managers could easily use this method in order to assess the ecological value of small habitats in mountainous regions and to provide guidelines for close-to-nature and conservation-related silviculture.FORET DE MONTAGNE;ECOLOGIE FORESTIERE;EVALUATION;PROTECTION DE LA NATURE;ACER PSEUDOPLATANUS;METHODOLOGIE;HABITAT;VALEUR ECOLOGIQUE;NATURALITE;ALPES FRANCAISES;CHARTREUSE MASSIF;ACER PSEUDOPLATANUS;CHARTREUSE;INDICATORS;NATURALNESS;ECOLOGICAL VALUE

Geophysical Well-Log Analysis In Characterizing The Hydrology Of Crystalline Rocks Of The Canadian Shield

A full suite of geophysical logs, including nuclear, electric, acoustic transit-time, acoustic waveform, and acoustic televiewer logs, and high-resolution flowmeter measurements have been used to investigate the lithologic and hydrologic properties of three igneous plutons located on the southern margin of the Canadian shield. Geophysical logs were used to identify lithologic boundaries, determine the properties of unfractured granitic or gabbroic rocks, interpret and calibrate the results of surface geophysical surveys, and characterize permeable fracture zones that could serve as conduits for fluid migration. Nuclear and acoustic transit-time logs provided good quantitative correlation with changes in lithology. Electric logs yielded consistent qualitative correlations, with lower resistivities associated with more mafic lithologies. Lithologic contacts indentified on logs generally confirmed the results of surface electromagnetic, seismic, and gravity surveys. All major fracture zones intersected by boreholes were clearly indicated by the geophysical logs. Electric, epithermal-neutron, and acoustic transit-time logs gave the most consistent indications of fracturing, but the lithologic responses associated with some thin mafic intrusions were difficult to distinguish from possible fractures, and some steeply-dipping fractures were not indicated by conventional acoustic transit-time logs. Electric and neutron log response is attributed to the effect of clay minearl alteration products in the vicinity of fractures. This alteration may be indirectly related to permebaility, but no direct relationship between resistivity or neutron attenuation and permeability appears to exist. Tube-wave attenuation determined from acoustic waveform logs was related to the transmissivity of equivalent infinite, plane fractures; these results agree qualitatively, and possibly quantitatively with packer isolation and injection tests if the combined effects of differing scales of investigation and borehole enlargements in fracture zones are taken into account. Tube-wave attenuation in waveform logs also compares well with the permeability distributions determined from tube-wave generation in vertical seismic profiles. Comparison of conventional geophysical logs, acoustic televiewer images of the borehole wall, and fracture frequency distributions measured on core samples indicates that many fractures are completely sealed and have no effect on log response, whereas many more apparently sealed fractures have been slightly opened during drilling, and do provide some log response. High resolution flowmeter meaurements of natural flow in boreholes and comparison of packer isolation tests with log data indicate that a relatively few individual fractures often provide a large proportion of fracture zone transmissivity in the immediate vicinity of the borehole, and that the orientation of these fractures may not coincide with fracture zone orientation. These results indicate that the scale problem in relating borehole logs to regional configuration of fracture flow systems may be the most important consideration in the appplication of geophysical well logging to the characterization of ground water flow in crystalline rock bodies

Presse et délinquance ou comment lire entre les signes

Based on two newspapers published in different socio-political contexts, one in Nice, France, the other in Geneva, Switzerland, we would like to compare the way these two dailies view crimes against property. Does the journalist report theft, breach of trust or break and enter in the same way? Are the same variables used in the articles or are important changes made from one article to the other? If such is the case, who orders the changes in the structure of the articles? The work, which comprises a systematic list of six months daily articles, covers all typical situations published in the two newspapers. It seems, then, that the persons mentioned in the papers who belong to minority, as opposed to the majority groups, are generally presented as responsible for crime. It seems, too, that individuality disappears in the reconstruction of the reality by the media. All in all, the analysis shows that the press exercises only a relative influence on its readers

Analysis of total dose-induced dark current in CMOS image sensors from interface state and trapped charge density measurements

The origin of total ionizing dose induced dark current in CMOS image sensors is investigated by comparing dark current measurements to interface state density and trapped charge density measurements. Two types of photodiode and several thick-oxide-FETs were manufactured using a 0.18-µm CMOS image sensor process and exposed to 10-keV X-ray from 3 krad to 1 Mrad. It is shown that the radiation induced trapped charge extends the space charge region at the oxide interface, leading to an enhancement of interface state SRH generation current. Isochronal annealing tests show that STI interface states anneal out at temperature lower than 100°C whereas about a third of the trapped charge remains after 30 min at 300°C

Frequency and Scale Effects in the Optimization of Acoustic Waveform Logs

Previously formulated scaling laws relating acoustic waveforms in boreholes to frequency, tool size and borehole diameter were investigated by repeated logging of the same test interval with different frequencies, and by logging adjacent boreholes of different diameters with the same logging system. Acoustic source frequency bands were centered on approximately 15, 20 and 34 kilohertz. Borehole diameters were Band 17 centimeters for test intervals located at depths ranging from 100 to 400 meters in granite. Test intervals included zones of homogeneous rock and fracture zones that were independently characterized with acoustic televiewer logs and core from the B centimeter borehole. The high frequency transducer produced waveforms dominated by the tube wave mode in the B centimeter borehole, but by a complicated interference pattern produced by the superposition of three normal modes in the 17 centimeter borehole. The two lower frequency transducers produced waveforms in the 17 centimeter diameter borehole with power spectra dominated by the first normal mode. Various methods for picking shear arrivals produced shear velocities in close agreement with known values for all cases except for the data obtained with the high frequency transducer in the 17 centimeter diameter borehole. This result was attributed to the effects of mode superposition and enhanced attenuation of higher frequencies. Tube wave amplitudes constructed from the data obtained with the higher frequency transducer in the B centimeter borehole provided the most unambiguous indication of open fractures. The superior quality of these amplitude logs was attributed to the strong excitation of tube waves, as opposed to the primary excitation of the first normal mode by the two lower frequency transducers in the 17 centimeter borehole

Field Test of a Low-Frequency Sparker Source for Acoustic Waveform Logging

Low-frequency acoustic-energy sources for waveform logging have important applications in: 1) Verifying theoretical calculations; 2) generating tube waves in large-diameter boreholes; and 3) providing larger sample volumes in cases where borehole effects are important. A new low-frequency source was fabricated by modifying an existing acoustic-waveform logging system to discharge multiple capacitors in series with an automobile spark plug. The sparker source was tested in boreholes of 15- and 8-centimeter diameter in homogeneous granite containing isolated fractures. The sparker source produced repeatable waveforms with frequencies centered on 5 kilohertz in the 8-centimeter-diameter borehole, and 7 kilohertz in the 15-centimeter-diameter borehole, compared to frequencies near 15 kilohertz for the same system using a low-frequency magnetostrictive source. The lower-frequency sparker source excited consistently measurable tube waves, in agreement with theory. Test results also confirmed that lower-source frequencies greatly decreased sensitivity to borehole effects. Observed differences in frequency content and extent of shear-mode excitation in the two different diameter boreholes are probably related to differences in mode-excitation functions. The data confirm theoretical predictions that optimum shear-mode excitation occurs for source frequencies near normal-mode cutoff. Reflection of low-frequency tube waves appears to be an effective means for distinguishing between isolated open fractures and intervals containing extensive alteration around nearly impermeable fractures