Larzac Plateau Research Articles

A Return to the Grandmother of Modern Activism

From 1971 to 1981, a group of 103 farming families living on the French Larzac plateau united to protect their sheep farms and land from expropriation to create space for the planned extension of the nearby Larzac military camp. Five decades later, the name ‘Larzac’ still remains part of French collective memory as a symbol of local activism, directly contesting the legitimacy of nationwide centralised decision-making. This article analyses how the myth of the Larzac struggle as the grandmother of small-scale French collective action first emerged in French media coverage, as well as engagement by both the Larzac farmers and activists of the Occitan regionalist movement. It also shows how the continuous reappropriation of this myth has shaped other newer kinds of protest, as the memory of the Larzac is mobilised to speak to issues that are still relevant today, namely the protection of local regional identity and culture writ large.

Trait–environment relationships depend on species life history

AbstractQuestionPredicting the functional response of vegetation to environmental variations remains highly challenging. A first reason is that trait–environment relationships result from joint intraspecific and interspecific responses. A second reason is that most plant communities host sets of species that are expected to display different environmental responses according to their ecophysiological strategies.LocationMediterranean rangeland, Larzac Plateau, France (“La Fage” INRAE experimental station: 43°55′ N, 3°05′ E).MethodsIn a Mediterranean rangeland, we tested whether changes in trait values in response to management intensification (increased resource availability and grazing intensity) differ between annuals and perennials that coexist locally. To capture the multiple facets of plant phenotypes, we studied nine traits related to carbon acquisition and conservation, plant size, water‐use efficiency, phenology and reproduction.ResultsFor most traits, we evidenced a significant interaction between environment and life history. In particular, changes in trait values were higher in perennials for leaf traits related to tissue density and growth. These differences were explained by: (a) a lower species turnover in annuals, and (b) the presence of species with more distinct trait values across environments in perennials. For most traits, these changes were not accompanied by differential intraspecific variations between annuals and perennials, which invalidates previous theoretical predictions. In addition, the contribution of intraspecific trait variation to among‐communities trait variance was higher for annuals than perennials for most traits.ConclusionAltogether, our findings highlight that changes in trait values with the environment can depend on functional groups (here, life history), which can further critically impact the assessment of the functional response of communities. They challenge the mean field approaches to communities in which trait aggregation is most often blindly applied, without considering potential different trajectories in response to environmental changes at various nested organizational levels.

Effect of fast drainage in karst sinkholes on surface runoff in Larzac Plateau, France

Study regionA 1 km² mountainous karst watershed on the Larzac Plateau in Southern France. Study focusThe village of La Vacquerie, located at the outlet of the watershed, is punctually affected by flash floods during storm events. On the contrary, no runoff is observed in the village during other rainfalls. A sinkhole, draining surface flows at the entrance of the village, plays a role on these differences. Descriptions of short and intense rainfalls in 2015 (avg. 40 mm/h over 5 h) and long and light events in 2014/2016 (avg. 8 mm/h over 25 h) provide valuable data to calibrate inputs of a distributed physic-based flow model, in particular the sinkhole drainage capacity. This study aims to quantify drainage capacity changes with rainfall characteristics and to find the rain intensity threshold at which runoff exceeds sinkhole capacity. New hydrological insights for the regionThe hydrological water balance of the hydrosystem is affected by the intensity variations for each of the different rain events. It shows the limited part of drainage in sinkhole (10%) during long light rains but its significant increase (40%) during short and intense rains. Drainage in sinkhole is affected by intensity variations rather than by the total amount of precipitation. When intensity exceeds 110 mm/h the sinkhole is submerged. However, this result is obtained in a case of Plateau configuration, where the saturated level, located deep below the surface (here 500 m), does not retro-affect drainage in the sinkhole.

Monitoring Saturation Changes with Ambient Seismic Noise and Gravimetry in a Karst Environment

Core Ideas Saturation changes can be monitored with ambient seismic noise. We present a new and nondestructive tool to investigate deep and heterogeneous vadose zones. At the site scale, this tool fills the gap between local boreholes and global basin information. Different geophysical datasets can be assimilated for hydrological model calibration. On a heterogeneous karstic site in the Larzac plateau (France), we performed cross‐correlations of ambient seismic noise recorded at two broadband seismometers to obtain daily seismic velocity changes. Rayleigh velocity changes at the 6‐ to 8‐Hz frequency band show variations of ±0.2% over 1 yr. Assuming a simple velocity profile, changes are expected to come from depths of tens of meters. Therefore velocity changes at 6 to 8 Hz were interpreted as induced by water saturation changes. A slow infiltration rate would explain the delay of several months between the rainy season (November) and the minimum velocity (June). Superconducting gravimeter, evapotranspiration, and magnetic resonance sounding (MRS) measurements were then combined with seismic data in one‐dimensional physical simulations. Velocity changes clearly constrain hydrological parameters, like saturated hydraulic conductivity, even if the Biot–Gassmann theory does not explain all of the amplitude observed. Nevertheless, this nondestructive method demonstrates great potential in hydrological model calibration. It overcomes the lack of depth resolution of gravimetry and the lack of temporal resolution of MRS. The combination of ambient seismic noise with gravimetry and MRS could fill the instrumental gap currently existing in hydrology for the study of deep and/or complex critical zones.

Landsliding generated by thermomechanical interactions between rock columns and wedging blocks: Study case from the Larzac Plateau (Southern France)

The Larzac Plateau is delimited by vertical cliffs whose geometry is controlled by vertical joints. Cliff’s erosion involves landslides initiated by incremental enlargement of joints that progressively detach rock columns at very low velocities (1.2 mm/yr). We find that enlargement of joints is linked to intraseasonal thermal cycles ranging between 2-15 days in relation with dilation/contraction of rock blocks trapped inside the joints. The mechanism involves two successive stages in which blocks create a wedging and a ratcheting effect on the rock column. Wedging is associated with compressional forces acting on the rock column, resulting from temperature increase and dilation of the shallow rocks. Ratcheting is associated with downward displacement of blocks by gravity to a new equilibrium position, resulting from temperature decrease and contraction of shallow rocks. The displacement vector in a thermal cycle is split into a plastic and a thermal component; plastic displacements range between 10 — 200 μm according to the seasons, and are absorbed along a shear plane dipping ~40° beneath the rock column: they are largest during autumn and winter, minor during spring and negligible in summer. This deformation mechanism is termed thermomechanical creep as permanent deformations are associated to mechanical forces induced by short-term thermal cycles.

Assessing the precision of the iGrav superconducting gravimeter for hydrological models and karstic hydrological process identification

In this paper we present the potential of a new compact superconducting gravimeter (GWR iGrav) designed for groundwater monitoring. At first, 3 yr of continuous gravity data are evaluated and the performance of the instrument is investigated. With repeated absolute gravity measurements using a Micro-g Lacoste FG5, the calibration factor (−894.8 nm s−2 V−1) and the long-term drift of this instrument (45 nm s−2 yr−1) are estimated for the first time with a high precision and found to be respectively constant and linear for this particular iGrav. The low noise level performance is found similar to those of previous superconducting gravimeters and leads to gravity residuals coherent with local hydrology. The iGrav is located in a fully instrumented hydrogeophysical observatory on the Durzon karstic basin (Larzac plateau, south of France). Rain gauges and a flux tower (evapo-transpiration measurements) are used to evaluate the groundwater mass balance at the local scale. Water mass balance demonstrates that the karst is only capacitive: all the rainwater is temporarily stored in the matrix and fast transfers to the spring through fractures are insignificant in this area. Moreover, the upper part of the karst around the observatory appears to be representative of slow transfer of the whole catchment. Indeed, slow transfer estimated on the site fully supports the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. In the last part of the paper, reservoir models are used to characterize the water transfer and storage processes. Particular highlights are done on the advantages of continuous gravity data (compared to repeated campaigns) and on the importance of local accurate meteorological data to limit misinterpretation of the gravity observations. The results are complementary with previous studies at the basin scale and show a clear potential for continuous gravity time-series assimilation in hydrological simulations, even on heterogeneous karstic systems.

Contribution of magnetic resonance soundings for characterizing water storage in the unsaturated zone of karst aquifers

Understanding the role of the unsaturated zone in aquifer recharge and contaminant attenuation processes is a major challenge for the protection and management of karstic water resources. We present the potential of the magnetic resonance soundings (MRS) geophysical method for characterizing the vadose zone of karst aquifers composed of epikarst and infiltration layers. To investigate the hydraulic functioning of the Durzon karst system located on the Larzac plateau (southern France), we used the MRS method at 16 sites. The MRS results have been compared with available geologic information and to core water content measurements. The remarkable spatial variability of the MRS response observed in the study area makes it possible to determine ranges of water storage properties in relation to the lithology of the investigated carbonate formations (dolomite, marly, and siliceous limestone). All soundings found either constant or increasing MRS water content with depth, which demonstrates that the infiltration zone might be the major water storage entity for permanent water storage, with important consequences for recharge quality and quantity. These results show the feasibility and potential of the MRS method for the characterization of the karst unsaturated zone and for understanding the vertical distribution of water content, which impacts the overall functioning of karst systems.

Ability of High-Resolution Resistivity Tomography to Detect Fault and Fracture Zones: Application to the Tournemire Experimental Platform, France

The Experimental Platform of Tournemire (Aveyron, France) developed by IRSN (French Institute for Radiological Protection and Nuclear Safety) is composed of a tunnel excavated in an argillite formation belonging to a limestone–argillite–limestone subhorizontal sedimentary sequence. Subvertical secondary fault zones were intercepted in argillite using drifts and boreholes in the tunnel excavated at a depth of about 250 m located under the Larzac Plateau. A 2D 2.5 km baseline large-scale electrical resistivity survey conducted in 2007 allowed detecting in the upper limestones several significantly low electrical resistivity subvertical zones (Gelis et al. Appl Geophys 167(11): 1405–1418, 2010). One of these discontinuities is consistent with the extension towards the surface of the secondary fault zones identified in the argillite formation from the tunnel. In an attempt to better characterize this zone, IRSN and MINES ParisTech conducted a high-resolution electrical resistivity survey located transversally to the fault and fracture zones. A 760-m-long profile was acquired using two array geometries and take-outs of 2, 4 and 8 m, requiring several roll-alongs. These data were first inverted independently for each take-out and then using all take-outs together for a given array geometry. Different inverted 2D electrical resistivity models display the same global features with high (higher than 5000 Ωm) to low (lower than 100 Ωm) electrical resistivity zones. These electrical resistivity models are finally compared with a geological cross-section based on independent data. The subvertical conductive zones are in agreement with the fault and fracture locations inferred from the geological cross-section. Moreover, the top of a more conductive zone, below a high electrical conductive zone and between two subvertical fault zones, is located in a more sandy and argillaceous layer. This conductive zone is interpreted as the presence of a more scattered fracture zone located at depth between two fault zones. This zone could be correlated with the fractured zones identified at 250-m depth in underground works. This study highlights the interest of multi-scale approaches to image complex heterogeneous near subsurface layers. Finally, this study shows that the electrical resistivity tomography is a useful and powerful tool to detect fault and fracture zones in upper limestones. Such a method is complementary to other geophysical and geological data.

The Transnational in the Local: The Larzac Plateau as a Site of Transnational Activism since 1970

This article explores the case of the Larzac plateau in southern France which was the site of protests against the extension of a military base in the 1970s. It analyses the development of the site as a focus of local, national and transnational protest, drawing in post-1968 gauchistes in France and West Germany. After the cancellation of the military base the Larzac protest became a model for protest from Latin America to the Pacific against the threats of globalization, which in turn transformed local protest. The limits of transnationalism were nevertheless demonstrated by contested understandings of the Larzac model of non-violent protest by activists from different contexts with their own agendas.

Fire salamander (Salamandra salamandra) in Larzac plateau: low occurrence, pond-breeding and cohabitation of larvae with paedomorphic palmate newts (Lissotriton helveticus)

th November; revised on 2014, 18 th January; accepted on 2014, 31 st January Abstract. Alternative reproductive strategies are widespread in caudate amphibians. Among them, fire salamanders (Salamandra salamandra) usually rely on streams to give birth to aquatic larvae but also use ponds, whereas palmate newt larvae (Lissotriton helveticus ) typically metamorphose into terrestrial juveniles, but can also reproduce in retain- ing their gills, a process known as paedomorphosis. Here we report repeated observations of an unusual case of coex- istence of these two alternative traits in the same pond (Larzac, France). The prevalence of fire salamanders in South- ern Larzac was very low (pond occupancy: 0.36%). The observed abundance of fire salamander larvae and paedo- morphic newts was also low in the studied pond. On one hand, the rarity of this coexistence pattern may suggest that habitat characteristics may not be optimal or that competition or predation processes might be operating. However, these hypotheses remain to be tested. On the other hand, as this is the only known case of breeding in Southern Lar - zac, it could be considered to be at a high risk of extirpation.

On the impact of topography and building mask on time varying gravity due to local hydrology

We use 3 yr of surface absolute gravity measurements at three sites on the Larzac plateau (France) to quantify the changes induced by topography and the building on gravity time-series, with respect to an idealized infinite slab approximation. Indeed, local topography and buildings housing ground-based gravity measurement have an effect on the distribution of water storage changes, therefore affecting the associated gravity signal. We first calculate the effects of surrounding topography and building dimensions on the gravity attraction for a uniform layer of water. We show that a gravimetric interpretation of water storage change using an infinite slab, the so-called Bouguer approximation, is generally not suitable. We propose to split the time varying gravity signal in two parts (1) a surface component including topographic and building effects (2) a deep component associated to underground water transfer. A reservoir modelling scheme is herein presented to remove the local site effects and to invert for the effective hydrological properties of the unsaturated zone. We show that effective time constants associated to water transfer vary greatly from site to site. We propose that our modelling scheme can be used to correct for the local site effects on gravity at any site presenting a departure from a flat topography. Depending on sites, the corrected signal can exceed measured values by 5-15 μGal, corresponding to 120-380 mm of water using the Bouguer slab formula. Our approach only requires the knowledge of daily precipitation corrected for evapotranspiration. Therefore, it can be a useful tool to correct any kind of gravimetric time-series data.

Monitoring deformation from hydrologic processes in a karst aquifer using long‐baseline tiltmeters

The aim of this study is to bring new information on water storage dynamics in karst systems from tiltmeter measurements. Newly developed long‐base hydrostatic tiltmeters are installed at two sites on the Larzac plateau (France) in a karst aquifer of ∼100 km2 recharge area. Each site is located within a karst cave where two tilt directions are monitored. Significant reversible tilt deformation reaching amplitudes of 10−6 to 10−5 rad was observed at both sites following heavy precipitation. Elastic parameters were determined with an experiment in which a tiltmeter site was loaded by up to 25 t of weight at strategic locations at the ground surface. Mechanisms responsible for the observed tilt were then examined by means of finite element modeling. Deformation induced by water pressure changes in fractures is our preferred interpretation as the most plausible mechanism. Within this scope, we used the tiltmeter responses to extract time constants using lumped parameter modeling. Time constants are interpreted to be associated with the filling and emptying of fractures nearby the tiltmeters. These instruments therefore appear as useful tools to study the local dynamics of water infiltration in karst systems.

L’église Saint-Martin-de-Castries dépendance de l’abbaye de Gellone sur le Larzac (La Vacquerie-et-Saint-Martin-de-Castries, Hérault)

The programmed excavation of the Saint-Martin-de-Castries site, on the Larzac plateau, revealed the existence of a late medieval rural village to which an ecclesiastical establishment succeeds. The first sanctuary, which is the result of a private initiative, is soon linked to the Gellone abbey. The evolution of the ecclesial site depended on this association until it was abandoned.

Time-lapse surface to depth gravity measurements on a karst system reveal the dominant role of the epikarst as a water storage entity

SUMMARY In this study we attempt to understand the water storage variations in a karst aquifer on the Larzac Plateau (South of France) using ground-based gravimetry. Surface to 60 m depth gravity measurements are performed three times a year since 2006 down a pothole, in complement to monthly absolute gravity (AG) measurements at three sites. The time variations of the surface to depth (STD) gravity differences are compared with the AG variations. Using a simple Bouguer plate model, we find that the STD gravity differences are very similar to the AG variations. The STD gravity differences are then used to determine apparent density values. These integrative density values are compared with measured grain densities from core samples to obtain an apparent porosity and saturation change representative of the investigated depth. The apparent porosity ranges from 4.8 to 7.3 per cent. We then discuss on the repartition of the apparent physical properties with respect to the epikarst and infiltration zone karst structures. We argue that AG and STD differences monitor epikarst water storage variations. Within this scope, we discuss the fact that seasonal scale water storage variation occurs predominantly in the epikarst.

Uptake and fixation of Zn, Pb, and Cd by Thlaspi caerulescens: application in the cases of old mines of Mibladen and Zaida (West of Morocco)

Contaminated soils and mine tailings pose major environmental and agricultural problems worldwide. These problems may be partially solved by an emerging new technology: phytoremediation. This technique uses plants to extract soil contaminants from the ground. Thlaspi caerulescens is known to accumulate in their tissues several heavy metals from soil and aerial deposition. This study was conducted to screen plants growing on a contaminated site to determine their potential for metal accumulation. Seeds of T. caerulescens metallicolous have been collected in the vicinity of F.T. Laurent le Minier in the Pb–Zn mining district of les Malines (North of Montpellier, Southern France), and seeds of T. caerulescens non-metallicolous were sampled on Larzac Plateau (North of Montpellier, Southern France). Soil substrates were collected from a mine site of Mibladen and Zaida (West, Morroco). Cultivated plant and surface soil samples were analyzed for zinc, lead, and cadmium concentrations by inductively coupled plasma mass spectrometry. A non-metallicolous (NM) ecotype of T. caerulescens and a metallicolous (M) ecotype are compared for Pb, Cd, and Zn accumulation in shoot and root in five metal-contaminated soils and one uncontaminated soil. The growth of individuals from uncontaminated soil was greater than that of individuals from metal-contaminated soils. The NM populations had markedly higher root/shoot ratio compared to M populations. The results indicate that both ecotypes of T. caerulescens are highly tolerant of zinc and Cd. Ecotype NM had constitutively higher Zn uptake capacity than the M ecotype. T. caerulescens species accumulate higher amount of Zn and Cd in their tissues in polluted soil and, in both of the two ecotypes, the root Pb concentrations were much greater than those of the shoot Pb contents. From both uncontaminated and metal-contaminated soils, we conclude that T. caerulescens are interesting material for phytoremediation of zinc and cadmium.

Absolute gravity monitoring of water storage variation in a karst aquifer on the larzac plateau (Southern France)

In this study we attempt to understand the water storage variations in a karst aquifer on the Larzac Plateau (South of France) using absolute gravimetry. On this karst system, water input is exclusively rainfall and draining occurs at the Durzon perennial spring in a karstic valley. Our basis assumption is that water storage in the vadose zone (epikarst and infiltration zone) has a significant effect on surface gravity through Newtonian attraction. The karst aquifer is hence being monitored since January 2006 with monthly absolute gravity measurements at three sites. The gravity measurements are corrected for regional scale gravity using water storage models in order to obtain gravity variations related exclusively to the local water storage variations. The gravity variations exhibit an important seasonal component (10–15 μgal corresponding to a variation of equivalent water slab thickness of ∼24–36 cm). Water storage variation seen by gravimetry is not spatially uniform on the studied karst system, corroborating current geomorphologic observations and interpretations. Finally, we use a global mass balance consideration linking rainfall, evapotranspiration and spring discharge to provide a conceptual framework for the understanding of observed gravity variations.

Cultivating Autonomy

■ This article explores the resistance of alterglobalization activists on the Larzac plateau in southern France to various forms of power. As part of a technique of resistance activists cultivate themselves as `autonomous' political subjects and organize a movement considered to be an `autonomous' counterpower. In addition to being a political goal, autonomy is problematically tangled up in many aspects of their lives and is of frequent concern in their efforts to resist. Autonomy also constitutes a theoretical problem in anthropological discussions of power and resistance. An autonomous space of resistance is often assumed by social movement theorists or denied by those who argue that power and resistance are inseparable. I argue in this article that autonomy, understood as something socially relative rather than absolute, is produced in the process of resisting via particular practices through which power and resistance come to oppose one another.

From Larzac to the altermondialist mobilisation: Space in environmental movements

Political studies have been surprisingly silent about the analysis and the conceptualisation of space as a constituent element of environmental mobilisations. The Larzac plateau has been constituted as an iterative site of mobilisation and as an emblematic place of contention for the struggle against the extension of the military camp in the 1970s through to the recent altermondialist protest. The means by which a geographic place can be turned into a rhetorical argument of environmental mobilization and how activists use the argumentative resources provided by a physical place for mobilization purposes is explained through the analysis of the ‘malbouffe' cause.

Bringing the Empire back home: France in the global age

Thirty years ago, an international antiglobalization movement was born in the grazing lands of France’s Larzac plateau. In the 1970s, Larzac farmers were joined by others from around the world in their efforts to prevent the expansion of a local military base: by ecologists, religious pacifists, and urban leftists, and by social activists including American Indians and South American peasant leaders. In 1999 some of the same farmers who had fought the expansion of the base in the 1970s—including Jose Bove—dismantled the new local McDonald’s. That gesture was part of a protest against U.S. tariffs on specified French exports including Roquefort cheese, the region’s primary market product. The two struggles—the one against expanding a French army camp intended to train troops for postcolonial wars, the other against American economic might—were landmarks in the global campaign to preserve local cultures. They were also key episodes in the decades-long attempt by the French to define their cultural heritage within a much changed nation, a new Europe, and, especially, an American-dominated world. In Bringing the Empire Back Home , the inventive cultural historian Herman Lebovics provides a riveting account of how intense disputes about what it means to be French have played out over the past half-century, redefining Paris, the regions, and the former colonies in relation to one another and the world at large. In a narrative populated with peasants, people from the former colonies, museum curators, former colonial administrators, left Christians, archaeologists, anthropologists, soccer players and their teenage fans, and, yes, leading government officials, Lebovics reveals contemporary French society and cultures as perhaps the West’s most important testing grounds of pluralism and assimilation. A lively cultural history, Bringing the Empire Back Home highlights not only the political significance of France’s efforts to synthesize the regional, national, European, ethnic postcolonial, and global but also the chaotic beauty of the endeavor.

Tectonic evolution and related fracturing in the Causses Basin (Aveyron, France) : the Tournemire area example

Tectonic evolution and related fracturing in the Causses Basin (Aveyron, France) : the Tournemire area example