Mises en défens et plantations : étude synchronique de deux techniques de restauration pour améliorer les communautés végétales et les propriétés du sol dans des steppes arides dégradées (Algérie)

Steppes of arid Mediterranean zones are deeply threatened by desertification. To stop or alleviate ecological and economic problems associated with this desertification, management actions have been implemented since the last three decades. The struggle against desertification has become a national priority in some of these countries. In Algeria, several management techniques have been used to cope with desertification. This study aims to investigate the effect of two management techniques on vegetation, soil properties and pastoral value after four years of implementation. The two techniques were grazing exclosure which was widely set up in degraded steppes and plantations (consisting in plantation and grazing exclosure) in deeply degraded ones. 49 phytoecological and soil samples have been studied. Results showed that plant diversity, composition, vegetation cover and pastoral value were significantly higher in protected areas. Management techniques also affected soil surface elements (percentage of sand, coarse soil elements, bare silty crust, and bare ground), organic matter and soil nitrogen content. We also demonstrated that important differences between both techniques remain: plantation technique on heavily degraded soil results in a higher pastoral value of plant communities whereas grazing exclosure technique on lesser degraded soil favours plant diversityLe processus de désertification menace depuis de nombreuses années les milieux steppiques arides du bassin méditerranéen. Afin d'arrêter ou atténuer les problèmes écologiques et économiques associés à cette désertification, des actions de gestion ont été mises en œuvre depuis les trois dernières décennies. Cette lutte est devenue pour certains pays une priorité nationale. En Algérie, plusieurs techniques de gestion visant à limiter le surpâturage ont été utilisées parmi lesquelles la plantation d'Atriplex canescens provenant d'Amérique centrale et la mise en défens de larges surfaces. Cette étude synchronique compare l'impact de ces deux pratiques de gestion après quatre ans de mise en œuvre sur la flore, la valeur fourragère et plusieurs paramètres édaphiques. Les 49 relevés phytoécologiques effectués montrent des modifications de la composition floristique, ainsi que des augmentations de la diversité, du recouvrement de végétation et de la valeur pastorale avec la protection des parcelles. L'ordination des résultats sur un plan factoriel permet de caractériser les trajectoires des différentes formations en fonction du mode de gestion qui leur est appliqué. Ces résultats mettent en évidence des groupements à richesse modérée et haute valeur pastorale dans les plantations, alors que les mises en défens conduisent à des formations à richesse élevée mais à valeur pastorale plus faible. Les paramètres édaphiques mesurés sont également affectés par la gestion: diminution de la fraction sableuse, des éléments grossiers, de la pellicule de glaçage, du sol nu et augmentation de la teneur en matière organique et azote total. Les conséquences de ces deux modes de gestion en termes de restauration et de réhabilitation écologiques sont discutées

How to Blend a Robot within a Group of Zebrafish: Achieving Social Acceptance through Real-time Calibration of a Multi-level Behavioural Model

We have previously shown how to socially integrate a fish robot into a group of zebrafish thanks to biomimetic behavioural models. The models have to be calibrated on experimental data to present correct behavioural features. This calibration is essential to enhance the social integration of the robot into the group. When calibrated, the behavioural model of fish behaviour is implemented to drive a robot with closed-loop control of social interactions into a group of zebrafish. This approach can be useful to form mixed-groups, and study animal individual and collective behaviour by using biomimetic autonomous robots capable of responding to the animals in long-standing experiments. Here, we show a methodology for continuous real-time calibration and refinement of multi-level behavioural model. The real-time calibration, by an evolutionary algorithm, is based on simulation of the model to correspond to the observed fish behaviour in real-time. The calibrated model is updated on the robot and tested during the experiments. This method allows to cope with changes of dynamics in fish behaviour. Moreover, each fish presents individual behavioural differences. Thus, each trial is done with naive fish groups that display behavioural variability. This real-time calibration methodology can optimise the robot behaviours during the experiments. Our implementation of this methodology runs on three different computers that perform individual tracking, data-analysis, multi-objective evolutionary algorithms, simulation of the fish robot and adaptation of the robot behavioural models, all in real-time.Comment: 9 pages, 3 figure

Drilling their own graves:How the European oil and gas supermajors avoid sustainability tensions through mythmaking

This study explores how paradoxical tensions between economic growth and environmental protection are avoided through organizational mythmaking. By examining the European oil and gas supermajors’ ‘‘CEOspeak’’ about climate change, we show how mythmaking facilitates the disregarding, diverting, and/or displacing of sustainability tensions. In doing so, our findings further illustrate how certain defensive responses are employed: (1) regression, or retreating to the comforts of past familiarities, (2) fantasy, or escaping the harsh reality that fossil fuels and climate change are indeed irreconcilable, and (3) projecting, or shifting blame to external actors for failing to address climate change. By highlighting the discursive effects of enacting these responses, we illustrate how the European oil and gas supermajors self-determine their inability to substantively address the complexities of climate change. We thus argue that defensive responses are not merely a form of mismanagement as the paradox and corporate sustainability literature commonly suggests, but a strategic resource that poses serious ethical concerns given the imminent danger of issues such as climate change

Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins

Size shifts may be a by-product of alterations in life history traits driven by natural selection. Although this approach has been proposed for islands, it has not yet been explored in continental faunas. The trends towards size decrease experienced by some hipparionins constitute a good case study for the application of a life history framework to understand the size shifts on the continent. Here, we analysed bone microstructure to reconstruct the growth of some different-sized hipparionins from Greece and Spain. The two dwarfed lineages studied show different growth strategies. The Greek hipparions ceased growth early at a small size thus advancing maturity, whilst the slower-growing Spanish hipparion matured later at a small size. Based on predictive life history models, we suggest that high adult mortality was the likely selective force behind early maturity and associated size decrease in the Greek lineage. Conversely, we infer that resource limitation accompanied by high juvenile mortality triggered decrease in growth rate and a relative late maturity in the Spanish lineage. Our results provide evidence that different selective pressures can precipitate different changes in life history that lead to similar size shifts

Hotspots of biogeochemical activity linked to aridity and plant traits across global drylands

14 páginas.- 4 figuras.- 67 referencias.- The online version contains supplementary material available at https://doi.org/10.1038/s41477-024-01670-7Perennial plants create productive and biodiverse hotspots, known as fertile islands, beneath their canopies. These hotspots largely determine the structure and functioning of drylands worldwide. Despite their ubiquity, the factors controlling fertile islands under conditions of contrasting grazing by livestock, the most prevalent land use in drylands, remain virtually unknown. Here we evaluated the relative importance of grazing pressure and herbivore type, climate and plant functional traits on 24 soil physical and chemical attributes that represent proxies of key ecosystem services related to decomposition, soil fertility, and soil and water conservation. To do this, we conducted a standardized global survey of 288 plots at 88 sites in 25 countries worldwide. We show that aridity and plant traits are the major factors associated with the magnitude of plant effects on fertile islands in grazed drylands worldwide. Grazing pressure had little influence on the capacity of plants to support fertile islands. Taller and wider shrubs and grasses supported stronger island effects. Stable and functional soils tended to be linked to species-rich sites with taller plants. Together, our findings dispel the notion that grazing pressure or herbivore type are linked to the formation or intensification of fertile islands in drylands. Rather, our study suggests that changes in aridity, and processes that alter island identity and therefore plant traits, will have marked effects on how perennial plants support and maintain the functioning of drylands in a more arid and grazed world.This research was supported by the European Research Council (ERC grant 647038 (BIODESERT) awarded to F.T.M.) and Generalitat Valenciana (CIDEGENT/2018/041). D.J.E. was supported by the Hermon Slade Foundation (HSF21040). J. Ding was supported by the National Natural Science Foundation of China Project (41991232) and the Fundamental Research Funds for the Central Universities of China. M.D.-B. acknowledges support from TED2021-130908B-C41/AEI/10.13039/501100011033/Unión Europea Next Generation EU/PRTR and the Spanish Ministry of Science and Innovation for the I + D + i project PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033. O.S. was supported by US National Science Foundation (Grants DEB 1754106, 20-25166), and Y.L.B.-P. by a Marie Sklodowska-Curie Actions Individual Fellowship (MSCA-1018 IF) within the European Program Horizon 2020 (DRYFUN Project 656035). K.G. and N.B. acknowledge support from the German Federal Ministry of Education and Research (BMBF) SPACES projects OPTIMASS (FKZ: 01LL1302A) and ORYCS (FKZ: FKZ01LL1804A). B.B. was supported by the Taylor Family-Asia Foundation Endowed Chair in Ecology and Conservation Biology, and M. Bowker by funding from the School of Forestry, Northern Arizona University. C.B. acknowledges funding from the National Natural Science Foundation of China (41971131). D.B. acknowledges support from the Hungarian Research, Development and Innovation Office (NKFI KKP 144096), and A. Fajardo support from ANID PIA/BASAL FB 210006 and the Millennium Science Initiative Program NCN2021-050. M.F. and H.E. received funding from Ferdowsi University of Mashhad (grant 39843). A.N. and M.K. acknowledge support from FCT (CEECIND/02453/2018/CP1534/CT0001, SFRH/BD/130274/2017, PTDC/ASP-SIL/7743/2020, UIDB/00329/2020), EEA (10/CALL#5), AdaptForGrazing (PRR-C05-i03-I-000035) and LTsER Montado platform (LTER_EU_PT_001) grants. O.V. acknowledges support from the Hungarian Research, Development and Innovation Office (NKFI KKP 144096). L.W. was supported by the US National Science Foundation (EAR 1554894). Y.Z. and X.Z. were supported by the National Natural Science Foundation of China (U2003214). H.S. is supported by a María Zambrano fellowship funded by the Ministry of Universities and European Union-Next Generation plan. The use of any trade, firm or product names does not imply endorsement by any agency, institution or government. Finally, we thank the many people who assisted with field work and the landowners, corporations and national bodies that allowed us access to their land.Peer reviewe

La mise en défens et la plantation fourragère : deux modes de restauration pour améliorer la végétation, la fertilité et l'état de la surface du sol dans les parcours arides algériens

Fencing and planting: two restoration strategies for the improvement of vegetation, soil fertility and soil surface properties in Algerian arid rangelands. Description of the subject. The struggle against desertification and the implementation of consecutive steppic ecosystem protection plans have become a priority in Algeria over the last four decades. Among the restoration techniques set up to manage or even restore sensitive steppic rangelands have been (i) fencing and (ii) fencing and the planting of exotic shrubs. Objectives. This study aims at describing the effect of these two restoration modes with control plots after four years on soil physico-chemical and surface state parameters and phyto-ecological properties. Method. Three hundred twelve phyto-ecological and pedological relevés were performed both on the restored plots and on controls four years after the initial implementation of management strategies. Phyto-ecological, soil surface and soil chemical parameters were measured for each modality. Results. Numerous parameters differed between the restored plots and the controls, including levels of total nitrogen and soil organic matter. However, textural parameters did not differ between the restored and the control plots. Conclusions. Our study shows that the implementation of both the restoration techniques in an arid region led within a relatively short space of time (four years) to an improvement in soil physico-chemical properties. We recommend the measurement of the percentage of coarse elements on the soil surface as an indicator of the system restoration state, and the use of the results as an important decision-making tool in reopening restored areas to grazing

Absorptions UV dans le fonctionnement des sources lasers solides à ions de terres rares

L'article donne une description et analyse les phénomènes d'absorption UV à l'origine des mécanismes de solarisation et de variation d'indice de réfraction observés dans certains matériaux dopés terres rares étudiés pour leurs propriétés laser UV ou infrarouge lorsqu'ils sont soumis à de fortes densités d'excitation optique

Grazing exclosure and plantation: a synchronic study of two restoration techniques improving plant community and soil properties in arid degraded steppes (Algeria)

Steppes of arid Mediterranean zones are deeply threatened by desertification. To stop or alleviate ecological and economic problems associated with this desertification, management actions have been implemented since the last three decades. The struggle against desertification has become a national priority in some of these countries. In Algeria, several management techniques have been used to cope with desertification. This study aims to investigate the effect of two management techniques on vegetation, soil properties and pastoral value after four years of implementation. The two techniques were grazing exclosure which was widely set up in degraded steppes and plantations (consisting in plantation and grazing exclosure) in deeply degraded ones. 49 phytoecological and soil samples have been studied. Results showed that plant diversity, composition, vegetation cover and pastoral value were significantly higher in protected areas. Management techniques also affected soil surface elements (percentage of sand, coarse soil elements, bare silty crust, and bare ground), organic matter and soil nitrogen content. We also demonstrated that important differences between both techniques remain : plantation technique on heavily degraded soil results in a higher pastoral value of plant communities whereas grazing exclosure technique on lesser degraded soil favours plant diversity.Mises en défens et plantations : étude synchronique de deux techniques de restauration pour améliorer les communautés végétales et les propriétés du sol dans des steppes arides dégradées (Algérie). Le processus de désertification menace depuis de nombreuses années les milieux steppiques arides du bassin méditerranéen. Afin d’arrêter ou atténuer les problèmes écologiques et économiques associés à cette désertification, des actions de gestion ont été mises en oeuvre depuis les trois dernières décennies. Cette lutte est devenue pour certains pays une priorité nationale. En Algérie, plusieurs techniques de gestion visant à limiter le surpâturage ont été utilisées parmi lesquelles la plantation d’Atriplex canescens provenant d’Amérique centrale et la mise en défens de larges surfaces. Cette étude synchronique compare l’impact de ces deux pratiques de gestion après quatre ans de mise en œuvre sur la flore, la valeur fourragère et plusieurs paramètres édaphiques. Les 49 relevés phytoécologiques effectués montrent des modifications de la composition floristique, ainsi que des augmentations de la diversité, du recouvrement de végétation et de la valeur pastorale avec la protection des parcelles. L’ordination des résultats sur un plan factoriel permet de caractériser les trajectoires des différentes formations en fonction du mode de gestion qui leur est appliqué. Ces résultats mettent en évidence des groupements à richesse modérée et haute valeur pastorale dans les plantations, alors que les mises en défens conduisent à des formations à richesse élevée mais à valeur pastorale plus faible. Les paramètres édaphiques mesurés sont également affectés par la gestion : diminution de la fraction sableuse, des éléments grossiers, de la pellicule de glaçage, du sol nu et augmentation de la teneur en matière organique et azote total. Les conséquences de ces deux modes de gestion en termes de restauration et de réhabilitation écologiques sont discutées.Amghar Fateh, Forey E., Margerie P., Langlois E., Brouri Lakh, Kadi-Hanifi Halima. Grazing exclosure and plantation: a synchronic study of two restoration techniques improving plant community and soil properties in arid degraded steppes (Algeria). In: Revue d'Écologie (La Terre et La Vie), tome 67, n°3, 2012. pp. 257-269