Laboratoire de Géographie Physique et Environnementale


Nos tutelles


Nos partenaires


Accueil > Annuaire > Fiche personnelle

Christophe CORONA

Chercheur - CNRS
Équipe : "Dynamiques géoenvironnementales actuelles"
Contact :


ACL - Articles dans des revues à comité de lecture


  • Casteller Alejandro, Stoffel Markus, Crespo Sebastian, Villalba Ricardo, Corona Christophe et Bianchi Emilio« Flash floods in the Patagonian Andes: A dendrogeomorphological approach. », Geomorphology, 228, p. 116-123. DOI : 10.1016/j.geomorph.2014.08.022.
    Résumé : Flash floods represent a significant natural hazard in small mountainous catchments of the Patagonian Andes and have repeatedly caused loss to life and infrastructure. At the same time, however, documentary records of past events remain fairly scarce and highly fragmentary in most cases. In this study, we therefore reconstruct the spatiotemporal patterns of past flash flood activity along the Los Cipreses torrent (Neuquén, Argentina) using dendrogeomorphic methods. Based on samples from Austrocedrus chilensis, Pseudotsuga menziesii, and Nothofagus dombeyi, we document 21 flash flood events covering the period A.D. 1890–2009 and reconstruct mean recurrence intervals of events at the level of individual trees being impacted, which varies from 4 to 93 years. Results show that trees tend to be older (younger) in sectors of the torrent with gentler (steeper) slope gradients. Potential triggers of flash floods were analyzed using daily temperature and precipitation data from a nearby weather station. Weather conditions leading to flash floods are abundant precipitations during one to three consecutive days, combined with temperatures above the rain/snow threshold (2 °C) in the whole watershed.
    Mots-clés : Austrocedrus chilensis, Dendrogeomorphology, Nothofagus dombeyi, Patagonian Andes, Pseudotsuga menziesii.

  • Corona Christophe, Saez Jérôme Lopez, Stoffel Markus, Rovéra Georges, Edouard Jean-Louis et Guibal Frédéric« Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps », Frontiers in Ecology and Evolution, 2 (82), p. 10.3389/fevo.2014.00082. DOI : 10.3389/fevo.2014.00082.
    Résumé : Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven relict stands of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitude to a P. uncinata stand located at the alpine treeline. Two detrending procedures are used to reveal high- and low-frequencies embedded in annually resolved ring-width series. Growth response of P. uncinata to instrumental temperature and precipitation data is investigated by means of moving response function analyses. Results show an increase in the sensitivity of tree-ring widths to drought during previous summer in both stands. At the treeline stand, an increasing response to fall temperature is observed whereby fall temperature and radial tree growth increased in two synchronous steps around ~1930 and from ~1980-present. At the low-altitude stand, P. uncinata appears more drought sensitive and exhibits a sharp growth decline since the mid-1980s, coinciding with increasing summer temperatures. Growth divergence between the two stands can be observed since the mid-1980s. We argue that the positive growth trend at the high-altitude stand is due to increasing fall temperatures which would favor the formation of metabolic reserves in conjunction with atmospheric CO2 enrichment that in turn would facilitate improved water use efficiency. At the relict low-altitude stand, in contrast, it seems that improved water use efficiency cannot compensate for the increase in summer temperatures.
    Mots-clés : climate change, dendroclimatology, elict pine stand, French Alps, response functions, tree-growth decline.

  • Morel Pauline, Trappmann Daniel, Corona Christophe et Stoffel Markus« Defining sample size and sampling strategy for dendrogeomorphic rockfall reconstructions », Geomorphology, p. doi:10.1016/j.geomorph.2015.02.017. DOI : 10.1016/j.geomorph.2015.02.017.
    Résumé : Optimized sampling strategies have been recently proposed for dendrogeomorphic reconstructions of mass movements with a large spatial footprint, such as landslides, snow avalanches, and debris flows. Such guidelines have, by contrast, been largely missing for rockfalls and cannot be transposed owing to the sporadic nature of this process and the occurrence of individual rocks and boulders. Based on a data set of 314 European larch (Larix decidua Mill.) trees (i.e., 64 trees/ha), growing on an active rockfall slope, this study bridges this gap and proposes an optimized sampling strategy for the spatial and temporal reconstruction of rockfall activity. Using random extractions of trees, iterative mapping, and a stratified sampling strategy based on an arbitrary selection of trees, we investigate subsets of the full tree-ring data set to define optimal sample size and sampling design for the development of frequency maps of rockfall activity. Spatially, our results demonstrate that the sampling of only 6 representative trees per ha can be sufficient to yield a reasonable mapping of the spatial distribution of rockfall frequencies on a slope, especially if the oldest and most heavily affected individuals are included in the analysis. At the same time, however, sampling such a low number of trees risks causing significant errors especially if nonrepresentative trees are chosen for analysis. An increased number of samples therefore improves the quality of the frequency maps in this case. Temporally, we demonstrate that at least 40 trees/ha are needed to obtain reliable rockfall chronologies. These results will facilitate the design of future studies, decrease the cost–benefit ratio of dendrogeomorphic studies and thus will permit production of reliable reconstructions with reasonable temporal efforts.
    Mots-clés : Dendrogeomorphology, frequency, mass movement, Methodology, Rockfall, simulation.

  • Corona Christophe, Saez Jérôme Lopez et Stoffel Markus« Defining optimal sample size, sampling design and thresholds for dendrogeomorphic landslide reconstructions », Quaternary Geochronology, 22 (22), p. 72-84. DOI : 10.1016/j.quageo.2014.02.006.
    Résumé : Trees affected by mass movements record the evidence of geomorphic disturbance in their growth-ring series, and thereby provide a precise geochronological tool for the reconstruction of past process activity. At the tree scale, identification of past mass movements was typically based on the presence of growth anomalies and focused on the presence of scars, tilted or buried trunks, as well as on apex decapitation. In terms of sampling strategy, however, clear guidelines have been largely missing. Most previous work was based either on the sampling of visibly disturbed trees irrespective of their position at the study site or on the systematic sampling of trees evenly distributed along transects. Based on a dense dataset of 323 trees growing on an active landslide body, this study aims at defining guidelines for future tree-ring sampling of landslides. Using random extractions of trees and iterative mapping, we investigate subsets of the full tree-ring sample to define optimal sampling strategy, sample depth and trees for the development of frequency maps of landslide reactivations. We demonstrate that (i) the sampling of 50-100 trees can be sufficient to obtain satisfactory results on landslide frequency without including noise to the dendrogeomorphic record; (ii) increasing growth disturbance thresholds should be adjusted to sample size and are preferable to fixed values; (iii) an even distribution of sampled trees is crucial to increase the reliability of frequency maps, even more so if the reconstruction is based on small sample sizes; and that (iv) the selection of the most frequently disturbed trees is key to reduce uncertainties in the frequency maps. The optimization of sample sizes and the adjustment of sampling strategy will not only facilitate fieldwork and render analyses and interpretation more reliable, but will also ultimately allow reconstruction of time series of past mass movements with reasonable temporal efforts and excellent cost-benefit ratios.
    Mots-clés : Dendrogeomorphology, mass movement, Sample size, Sampling design, Spatial analysis.

  • Saez Jérôme Lopez, Corona Christophe, Stoffel Markus et Berger Frédéric« Assessment of forested shallow landslide movements coupling tree ring records from stems and exposed roots », Géomorphologie : Relief. Processus. Environnement, 2/2014, p. 159-174. DOI : 10.4000/geomorphologie.10616.
    Résumé : The purpose of this study is to explore and illustrate the potential of exposed roots to reconstruct larger-scale landslide activity and thus to complement tree-ring data gathered from stems to reconstruct spatio-temporal patterns of landslide reactivation. Work was undertaken in a forested area of the Davids-Bas landslide, Barcelonnette (Southeastern French Alps) and based on growth disturbances (GD) from 48 stems and on anatomical changes (decrease of cell lumina) in 20 exposed root sections of heavily affected Mountain pine (Pinus uncinata Mill. ex Mirb.) trees growing on the scarps and upon the landslide body. A total of 95 GD and 20 anatomical changes were identified in the samples pointing to 7 movements of the landslide body since AD 1977. The study demonstrates that reconstructions of landslide reactivations obtained from exposed roots samples are not significantly different from those gathered from stems, but that the inclusion of exposed roots permits realization of frequency maps in sectors which could not be documented with classic dendrogeomorphic approaches focusing on tree-ring records from stems (scars, cracks). In addition, and even more importantly, the inclusion of exposed roots allowed assessment of the geomorphic evolution of the landslide at the local scale and to detect precursor signals of major reactivations in the form of crack widening before the main movement was registered in the tree stems. In that sense, the combined approach presented in this paper can be considered as a valuable tool for land-use planners and emergency cells in charge of forecasting future events and in protecting people and their assets from the negative effects of landslides.
    Mots-clés : Dendrogeomorphology, exposed root, French Alps, landslide.

  • Stoffel Markus et Corona Christophe« Dendroecological dating of geomorphic disturbance in trees », Tree-Ring Research, 70 (1), p. 3-20. DOI : 10.3959/1536-1098-70.1.3.
    Résumé : The initial employment of tree rings in geomorphic studies was simply as a dating tool and only rarely were other environmental information and records of damage contained within the tree exploited. However, these annually resolved tree-ring records also preserve valuable archives of past geomorphic processes on timescales of decades to centuries. As many of these processes are significant natural hazards, understanding their distribution, timing and controls provides crucial information that can assist in the prediction, mitigation and defense against these hazards and their effects on society. This contribution aims at presenting a proposal on the types of growth disturbances to be included in future work focusing on geomorphic disturbance, the intensity of reactions, and on the minimum requirements needed for growth disturbances to be considered in event histories. We present possibilities and limitations of dendrogeomorphic applications in geomorphic research and propose a range of techniques and approaches that may become standard practice in the analysis and understanding of earth-surface processes and related natural hazards in the future.
    Mots-clés : Dendrogeomorphology, earth-surface process, geomorphology, hydrogeomorphology, injury, reaction wood, resin duct, tracheid, vessel, Wood anatomy.

  • Trappmann Daniel, Stoffel Markus et Corona Christophe« Achieving a more realistic assessment of rockfall hazards by coupling three-dimensional process models and field-based tree-ring data », Earth Surface Processes and Landforms, 39 (114), p. 1866–1875. DOI : 10.1002/esp.3580.
    Résumé : Sound knowledge of the spatial and temporal patterns of rockfalls is fundamental for the management of this very common hazard in mountain environments. Process-based, three-dimensional simulation models are nowadays capable of reproducing the spatial distribution of rockfall occurrences with reasonable accuracy through the simulation of numerous individual trajectories on highly-resolved digital terrain models. At the same time, however, simulation models typically fail to quantify the ‘real’ frequency of rockfalls (in terms of return intervals). The analysis of impact scars on trees, in contrast, yields real rockfall frequencies, but trees may not be present at the location of interest and rare trajectories may not necessarily be captured due to the limited age of forest stands. In this article, we demonstrate that the coupling of modeling with tree-ring techniques may overcome the limitations inherent to both approaches. Based on the analysis of 64 cells (40 m × 40 m) of a rockfall slope located above a 1631-m long road section in the Swiss Alps, we illustrate results from 488 rockfalls detected in 1260 trees. We illustrate that tree impact data cannot only be used (i) to reconstruct the real frequency of rockfalls for individual cells, but that they also serve (ii) the calibration of the rockfall model Rockyfor3D, as well as (iii) the transformation of simulated trajectories into real frequencies. Calibrated simulation results are in good agreement with real rockfall frequencies and exhibit significant differences in rockfall activity between the cells (zones) along the road section. Real frequencies, expressed as rock passages per meter road section, also enable quantification and direct comparison of the hazard potential between the zones. The contribution provides an approach for hazard zoning procedures that complements traditional methods with a quantification of rockfall frequencies in terms of return intervals through a systematic inclusion of impact records in trees.
    Mots-clés : 3D rockfall simulation models, Dendrogeomorphology, hazard assessment, rockfall frequency, Tree ring.

  • Corona Christophe, Trappmann Daniel et Stoffel Markus« Parameterization of rockfall source areas and magnitudes with ecological recorders: When disturbances in trees serve the calibration and validation of simulation runs », Geomorphology, 202, p. 33-42. DOI : 10.1016/j.geomorph.2013.02.001.

  • Rovera Georges, Lopez Saez Jérôme, Corona Christophe, Stoffel Markus et Berger Frédéric« Preliminary quantification of the erosion of sandy-gravelly cliffs on the island of Porquerolles (Provence, France) through dendrogeomorphology, using exposed roots of Aleppo pine (Pinus halepensis Mill.) », Geografia Fisica e Dinamica Quaternaria, p. 10.
    Résumé : This study is a first attempt to specify the geodynamic processes leading to the erosion of detrital quaternary cliffs on the island of Porquerolles, and to quantify the rate of erosion thanks to dendrogeomorphology. The island is located in the Mediterranean Sea, off the coast of Provence (France). The method identifies the roots of Aleppo pine (Pinus halepensis Mill.) that have been unearthed by cliff retreat. The year of denudation is revealed by the net change in tracheid anatomy in tree rings, so that we can establish the retreating rates of cliffs, and assess the ratio between the distance of loosening and the number of years since denudation. 13 root samples were used to determine that the cliff retreat is due to small rockfalls, at an average rate of 2.5 cm/a. This value is compared to other rates of erosion quantified on rocky or sandy shores. A review of the method and a comparison with methods based on photogrammetry and micrometrics are proposed.
    Mots-clés : Aleppo pine, Aleppo pine., Dendrogeomorphology, Erosion rate, Littoral geodynamics, Mediterranean Sea, Quaternary cliff, Tracheid root.

  • Saez Jérôme Lopez, Corona Christophe, Berger Frédéric et Stoffel Markus« Climate change increases frequency of shallow spring landslides in the French Alps », Geology, 41 (5), p. 619-622. DOI : 10.1130/G34098.1.
    Résumé : In this contribution, past process activity is reconstructed on seven landslide bodies of the Riou Bourdoux catchment (southeastern French Alps). Based on an unusually dense data set of 3036 tree-ring series extracted from 759 conifers, we provide evidence for 61 landslide reactivations since A.D. 1898. Based on logistic regressions and threshold analyses of monthly rainfall data and temperature anomalies, we determine that the combination of snow-rich winters and positive temperature anomalies in spring (enhanced snowmelt) seems to have driven landslide reactivations in the past. Since the early 1990s, however, landslide reactivations clearly have been on the rise and thereby exhibit excessive and unprecedented rates of activity (12.5 events per 10 yr) at the scale of the Riou Bourdoux catchment. From the data, evidence exists for a shift from snowmelt-induced landslides (controlled by winter precipitation) to reactivations controlled by spring temperatures. Therefore, this contribution also adds evidence to the hypothesis that climate change (and related warmer springs) could further enhance landslide activity in the course of the 21st century.
    Mots-clés : climate change, landslides, tree-ring.

  • Schläppy Romain, Jomelli Vincent, Grancher Delphine, Stoffel Markus, Corona Christophe, Brunstein Daniel, Eckert Nicolas et Deschatres Michael« A New Tree-Ring-Based, Semi-Quantitative Approach for the Determination of Snow Avalanche Events: use of Classification Trees for Validation », Arctic, Antarctic, and Alpine Research, 45 (3), p. 383-395. DOI : 10.1657/1938-4246-45.3.383.

  • Schneuwly-Bollschweiler Michelle, Corona Christophe et Stoffel Markus« How to improve dating quality and reduce noise in tree-ring based debris-flow reconstructions », Quaternary Geochronology, 18, p. 110-118. DOI : 10.1016/j.quageo.2013.05.001.

  • Stoffel Markus, Butler David R. et Corona Christophe« Mass movements and tree rings: A guide to dendrogeomorphic field sampling and dating », Geomorphology, 200, p. 106-120. DOI : 10.1016/j.geomorph.2012.12.017.

  • Stoffel Markus, Corona Christophe, Ballesteros-Cánovas Juan Antonio et Bodoque José Maria« Dating and quantification of erosion processes based on exposed roots », Earth-Science Reviews, 123, p. 18-34. DOI : 10.1016/j.earscirev.2013.04.002.
    Résumé : Soil erosion is a key driver of land degradation and heavily affects sustainable land management in various environments worldwide. An appropriate quantification of rates of soil erosion and a localization of hotspots are therefore critical, as sediment loss has been demonstrated to have drastic consequences on soil productivity and fertility. A consistent body of evidence also exists for a causal linkage between global changes and the temporal frequency and magnitude of erosion, and thus calls for an improved understanding of dynamics and rates of soil erosion for an appropriate management of landscapes and for the planning of preventive or countermeasures. Conventional measurement techniques to infer erosion rates are limited in their temporal resolution or extent. Long-term erosion rates in larger basins have been analyzed with cosmogenic nuclides, but with lower spatial and limited temporal resolutions, thus limiting the possibility to infer micro-geomorphic and climatic controls on the timing, amount and localization of erosion. If based on exposed tree roots, rates of erosion can be inferred with up to seasonal resolution, over decades to centuries of the past and for larger surfaces with homogenous hydrological response units. Root-based erosion rates, thus, constitute a valuable alternative to empirical or physically-based approaches, especially in ungauged basins, but will be controlled by individual or a few extreme events, so that average annual rates of erosion might be highly skewed. In this contribution, we review the contribution made by this biomarker to the understanding of erosion processes and related landform evolution. We report on recent progress in root-based erosion research, illustrate possibilities, caveats and limitations of reconstructed rates, and conclude with a call for further research on various aspects of root–erosion research and for work in new geographic regions.
    Mots-clés : dendrochronology, Dendrogeomorphology, Erosion rates, Exposed roots, Target areas, Wood anatomy.

  • Trappmann Daniel, Stoffel Markus et Corona Christophe« Rolling stones and tree rings: A state of research on dendrogeomorphic reconstructions of rockfall », Progress in Physical Geography, 37, p. 701-716. DOI : 10.1177/0309133313506451.
    Résumé : This progress report focuses on the contribution of tree-ring series to rockfall research and on recent development and challenges in the field. Dendrogeomorphic techniques have been used extensively since the early 2000s and several approaches have been developed to extract rockfall signals from tree-ring records of conifer trees. The reconstruction of rockfall chronologies has been hampered in the past by sample sizes that decrease as one goes back in time, as well as by a paucity of studies that include broadleaved tree species, which are in fact quite common in rockfall-prone environments. In this report, we propose a new approach considering impact probability and quantification of uncertainty in the reconstruction of rockfall time series as well as a quantitative estimate of presumably missed events. In addition, we outline new approaches and future perspectives for the inclusion of woody vegetation in hazard assessment procedures, and end with future thematic perspectives.
    Mots-clés : chronology, Dendrogeomorphology, frequency, hazard assessment, mass movement, Rockfall, simulation, Tree ring.

  • Arbellay Estelle, Corona Christophe, Stoffel Markus, Fonti Patrick et Decaulne Armelle« Defining an adequate sample of earlywood vessels for retrospective injury detection in diffuse-porous species », éd. par Ben Bond-Lamberty, PLoS ONE, 7 (6), p. e38824. DOI : 10.1371/journal.pone.0038824.
  • Astrade Laurent, Stoffel Markus, Corona Christophe et Lopez Saez Jérôme« Using tree rings to study events and morphological changes: relevance, methods, and contribution of Alpine research to dendrogeomorphology », Géomorphologie : relief, processus, environnement, 3, p. 295-316.

  • Corona Christophe, Lopez Saez Jérôme, Stoffel Markus, Bonnefoy Mylène, Richard Didier, Astrade Laurent et Berger Frédéric« How much of the real avalanche activity can be captured with tree rings? An evaluation of classic dendrogeomorphic approaches and comparison with historical archives », Cold Regions Science and Technology, 74-75, p. 31-42. DOI : 10.1016/j.coldregions.2012.01.003.

  • Corona Christophe, Lopez Saez Jérôme, Stoffel Markus, Rovera Georges, Edouard Jean-Louis et Berger Frédéric« Seven centuries of avalanche activity at Echalp (Queyras massif, southern French Alps) as inferred from tree-rings », The Holocene, 23 (2), p. 292-304.
    Résumé : The purpose of this study was to reconstruct spatio-temporal patterns of avalanche events in a forested avalanche path of the Queyras massif (Echalp avalanche path, Southeast French Alps). Analysis of past evnts was based on tree-ring series from 163 heavily affected multi-centennial larch trees (Larix decidua Mill.) near or next to the avalanche path. A total of 514 growth disturbances, such as tangential rows of traumatic resin ducts, the onset of compression wood as well as abrupt growth suppression or release, are identified in the samples indicating 38 destructive snow avalanches between 1338 and 2010. The mean return period of snow avalanches was 22 years with a 4% probability that avalanche occurs in a particular year. On a temporal plan, three maxima In snow avalanche frequency were reconstructed at the beginning of the 16th and 19th centuries and around 1850, correlating with above average winter temperatures and glacier advances. Analysis of the spatial distribution of disturbed trees contributed to the determination of four preferential patterns of avalanche events. The comparison of dendrogeomorphic data with historical records demonstrate that at least 18 events- six of were undocumented- reached the hamlet of Echalp during the last seven centuries, but no significant temporal trend was detected concerning the frequency of these extreme events.
    Mots-clés : Dendrogeomorphology, French Alps, frequency, last millennium, reconstruction, snow avalanche, tree-rings.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus et Berger Frédéric« High-resolution fingerprints of past landsliding and spatially explicit, probabilistic assessment of future reactivations: Aiguettes landslide, Southeastern French Alps », Tectonophysics. DOI : 10.1016/j.tecto.2012.04.020.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Schoeneich Philippe et Berger Frédéric« Probability maps of landslide reactivation derived from tree-ring records: Pra Bellon landslide, southern French Alps », Geomorphology, 138 (1), p. 189-202. DOI : 10.1016/j.geomorph.2011.08.034.

  • Corona Christophe, Edouard Jean-Louis, Guibal Frederic, Guiot Joel, Bernard Sylvain, Thomas Andre et Denelle Nicole« Long-term summer (AD751-2008) temperature fluctuation in the French Alps based on tree-ring data », Boreas, 40 (2), p. 351-366. DOI : 10.1111/j.1502-3885.2010.00185.x.
  • Corona Christophe, Edouard Jean-Louis, Guibal Frédéric, Lambert Georges-Noel, Py Vanessa, Guiot Joel et Thomas André« Last Millenium summer temperature variations in Briançonnais (French Alps) based on a composite tree-ring larch chronology », Scientia artis, 7, p. 26-41.

  • Corona Christophe, Lopez Saez Jérôme, Rovéra Georges, Stoffel Markus, Astrade Laurent et Berger Frédéric« High resolution, quantitative reconstruction of erosion rates based on anatomical changes in exposed roots at Draix, Alpes de Haute-Provence — critical review of existing approaches and independent quality control of results », Geomorphology, 125 (3), p. 433-444. DOI : 10.1016/j.geomorph.2010.10.030.

  • Corona Christophe, Lopez Saez Jérôme, Rovéra Georges, Astrade Laurent, Stoffel Markus et Berger Frédéric« Validation d’une méthode de quantification des vitesses d’érosion sur marnes par dendrogéomorphologie (Draix, Alpes de Haute-Provence) », Géomorphologie : relief, processus, environnement, 1/2011, p. 83-94. DOI : 10.4000/geomorphologie.9254.

  • Girard François, Vennetier Michel, Guibal Frédéric, Corona Christophe, Ouarmim Samira et Herrero Asier« Pinus halepensis Mill. crown development and fruiting declined with repeated drought in Mediterranean France », European Journal of Forest Research, 131 (4), p. 919-931. DOI : 10.1007/s10342-011-0565-6.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Astrade Laurent, Berger Frédéric et Malet Jean-Philippe« Dendrogeomorphic reconstruction of past landslide reactivation with seasonal precision: the Bois Noir landslide, southeast French Alps », Landslides, p. 189-203. DOI : 10.1007/s10346-011-0284-6.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Gotteland A., Berger Frédéric et Liébault F.« Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data », Natural Hazards and Earth System Science, 11, p. 1247-1257. DOI : 10.5194/nhess-11-1247-2011.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Rovéra Georges, Astrade Laurent et Berger Frédéric« Mapping of erosion rates in marly badlands based on a coupling of anatomical changes in exposed roots with slope maps derived from LiDAR data », Earth Surface Processes and Landforms, 36 (9), p. 1162-1171. DOI : 10.1002/esp.2141.

  • Rovera Georges, Corona Christophe et Lopez Saez Jérôme« High resolution, quantitative reconstruction of erosion rates based on anatomical changes in exposed roots at Draix, Alpes de Haute-Provence - critical review of existing approaches and independent quality control of results », Geomorphology, 125, p. 433-444.
    Résumé : Extensive areas of French Alps are underlain by Jurassic black marls. Wherever these "terres noires" crop out they become subject to intense erosion, causing major sedimentation in regional reservoirs and river systems. In the badlands near Draix (Alpes de Haute-Provence, France), measured sediment rates were obtained at the plot scale by surface elevation change-based methods and at the catchment scale by monitoring sedimentation in dams. In this study, we use a dendrogeomorphic approach based on anatomical changes in exposed roots of Pinus sylvestris L. to accurately quantify continuous denudation rates. A total of 123 cross sections (75 from buried and 48 from exposed roots of 23 trees) were sampled in the Moulin basin. The size and position of roots at the time of exposure was determined via anatomical variations in the annual growth rings of roots. In cross sections of buried roots, a sharp reduction of earlywood tracheid lumen area - a growth signature which has traditionally been used to determine the moment of root denudation - was observed as soon as erosion reduced soil cover to < 3 cm. As a consequence, estimates of eroded soil thickness had to be adjusted to take account of this bias. Bias-adjusted, averaged, medium term erosion rates derived from exposed roots vary between 6 and 7 mm y-1 at Moulin basin depending on the importance accorded to the uplift of roots after exposure. values are significantly correlated to slope angle and match with erosion rates derived from monitored iron stakes (5.7 mm y-1) or measurements of sediment yield in retention dams. (4.7 mm y-1) at the outlet of the Moulin basin. Besides demonstrating that the interpretation of anatomical signatures in tree roots to erosion have to be revised, this paper also shows that dendrogeomorphic analyses of roots are indeed a powerful tool for the quantification of minimal rates of soil erosion in environments where measurements of past activity are not available.
    Mots-clés : badlands, black marls, Dendrogeomorphology, earlywood tracheids, Erosion rates, Exposed roots, Pinus sylvestris L, Pinus sylvestris L..

  • Rovera Georges, Corona Christophe et Lopez Saez Jérôme« Quantification des vitesses d'érosion par dendrogéomorphologie : utilisation des racines déchaussées dans les badlands marneux des bassins expérimentaux de Draix (Alpes de Haute-Provence) », Géomorphologie : Relief. Processus. Environnement, 1, p. 83-94.
    Résumé : Les marnes noires du Jurassique couvrent de vastes surfaces dans les Alpes françaises du Sud. Partout où elles affleurent, elles sont sujettes à une érosion intense à l'origine de problèmes de sédimentation dans les cours d'eau et d'envasement dans les réservoirs hydro-électriques. Dans les badlands de Draix (Alpes de Haute-Provence), les vitesses d'érosion obtenues par différentes méthodes de mesure atteignent 5 à 10 mm/a. Dans cette étude, les mesures d'érosion quantifiées au moyen d'une approche dendrogéomorphologique sont validées par comparaison avec celles issues du suivi micrométrique d'un réseau de 47 tiges métalliques. Trente-neuf racines de Pinus sylvestris L. déchaussées ont été échantillonnées dans le bassin-versant du Moulin (8 ha) et l'impact de la dénudation sur les variations anatomiques des cernes annuels de croissance a été mesuré. L'année de déchaussement a pu être déterminée via l'étude de la diminution très rapide, de l'ordre de 60%, de la surface du lumen des trachéides. Les vitesses d'érosion mesurées au moyen de la dendrogéomorphologie atteignent en moyenne 5 mm/an et montrent une corrélation significative [r²(d)=0,39] mais non exclusive avec la pente locale. Elles concordent avec celles obtenues à partir de mesures micrométriques (5,7 mm/a en moyenne) et par cubages réalisés à l'exutoire du bassin-versant (4,7 mm/a). Dés lors, cette approche offre des perspectives particulièrement intéressantes pour quantifier et spatialiser rapidement les vitesses d'érosion moyennes sur plusieurs décennies, dans des bassins versants non instrumentés.
    Mots-clés : badlands, dendrogéomorphologie, micrométrie, racines, vitesse d'érosion.

  • Saulnier Mélanie, Edouard Jean-Louis, Corona Christophe et Guibal Frédéric« Climate/growth relationships in a Pinus cembra high-elevation network in the Southern French Alps », Annals of Forest Science, 68 (1), p. 189-200. DOI : 10.1007/s13595-011-0020-3.