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Abstract Landscape restoration initiatives are mainly focusing on forest regeneration and agroforestry, especially in the Global South. However, due to a lack of monitoring tools, the carbon balance of restoration efforts remains poorly quantified. Here, we use satellite images from 2008 and 2019 to calculate carbon stocks for individual trees in Rwanda, a country which has been actively engaged in restoration activities over the past decade. We show that smallholder farmers on average planted about 3 trees per farm during 2008–2019, contributing about 50.4 million new trees at the national scale. The overall C sink of the new farmland trees was 0.13 Megagrams of Carbon per hectare per year, which is 6 times lower than gains observed from restoration of degraded forests (0.76 Megagrams of Carbon per hectare per year). If national greenhouse gas emissions remain at the level of 2019, agroforestry (~61% of national area coverage) and continued restoration of degraded natural forests (~0.5% of national area coverage) have the potential to offset about 80% of the national emissions before 2050. Our work monitors and quantifies progress and impact of landscape restoration projects and outlines a pathway to engage smallholder farmers with a limited number of on-farm trees into the expanding carbon market.

Purpose – The purpose of this paper is to estimate the impact of the 2008 and 2020 economic crises on employment in Spain. Design/methodology/approach – The authors perform a counterfactual analysis, combining intervention (interrupted time series) analysis and conditional forecasting to estimate a “crisis-free” scenario. These counterfactual estimates are used as a synthetic control, to be compared with the observed values of the main variables of the Spanish Labor Force Survey (EPA). Findings – The authors measure the effect on Spanish employment of the 2008 recession and the ongoing COVID/Ukraine crisis and the speed of recovery, which yields a rigorous dating for the beginning and end of the crises studied. Finally, the authors provide estimates about which part of the employed and unemployed people was in furlough (ERTE) based on microdata provided by the Spanish Institute of Statistics. Originality/value – To the best of the authors’ knowledge, there are no counterfactual studies covering all the basic variables in EPA and no estimates for the effect of ERTEs on the basic employment variables. Finally, the authors combine well-known intervention and forecasting techniques into an integrated framework to assess the effects of both, past and ongoing crises.

Abstract The consistent monitoring of trees both inside and outside of forests is key to sustainable land management. Current monitoring systems either ignore trees outside forests or are too expensive to be applied consistently across countries on a repeated basis. Here we use the PlanetScope nanosatellite constellation, which delivers global very high-resolution daily imagery, to map both forest and non-forest tree cover for continental Africa using images from a single year. Our prototype map of 2019 (RMSE = 9.57%, bias = −6.9%). demonstrates that a precise assessment of all tree-based ecosystems is possible at continental scale, and reveals that 29% of tree cover is found outside areas previously classified as tree cover in state-of-the-art maps, such as in croplands and grassland. Such accurate mapping of tree cover down to the level of individual trees and consistent among countries has the potential to redefine land use impacts in non-forest landscapes, move beyond the need for forest definitions, and build the basis for natural climate solutions and tree-related studies.

Strengthening of feed security in the Sahel is urgently needed given the climate change and growing human population. A prerequisite to this is sustainable use of rangeland forage resources for livestock. Many studies have focused on the assessment of rangeland resources during the rainy season, while only a few have focused on the dry season which is the longest and most demanding period for livestock in Sahelian rangelands. The objective of this study is to develop remote sensing-based models for estimating dry season forage vegetation mass. To that end, 29 vegetation indices calculated from each of the MODIS-MCD43A4 (500 m), Landsat-8 (30 m), and Sentinel-2 (10 m) satellite products were used and tested against in situ data collected during three field-measurement campaigns in 2021 at eleven monitoring sites across Senegalese rangelands. Four statistical models were tested, namely, random forest, gradient boosting machines, and simple linear and multiple linear regressions. The two main vegetation mass variables modeled from remote sensing imagery were the standing herbaceous and litter dry mass (BH) and total forage dry mass (BT) with a dry mass of woody plant leaves added to BH. Overall, Sentinel-2 data provided the best performance for the assessment of BH with multiple linear regression (R2 = 0.74; RMSE = 378 kg DM/ha) using NDI5 (Normalized Difference Index5), GRCI (Green Residue Cover Index), SRI (Simple Ratio Index), TCARI (Transformed Chlorophyll Absorption in Reflectance Index), and DFI (Dead Fuel Index) indices. For BT, the best model was also obtained from Sentinel-2 data, including RVI3 (Ratio Vegetation Index3) (R2 = 0.78; RMSE = 496 kg DM/ha). Results showed the suitability of combining the red, green, blue, NIR, SWIR1, and SWIR2 bands in monitoring forage availability during the dry season. Our study revealed that the spectral richness of the optical sensor systems Sentinel-2, Landsat-8, and MODIS-MCD43A4 allowed for accurate assessments of dry-season forage mass of semi-arid rangelands. Adding to this, the high spatial and temporal resolution of Sentinel-2 satellite imagery makes this a promising data source for timely monitoring. These findings can support the monitoring of the animal feed balance in Sahelian countries and contribute to enhancing the resilience of pastoralism toward feed shortage through early warning systems.

West African Sahelian and Sudanian ecosystems provide essential services to people and also play a significant role within the global carbon cycle. However, climate and land use are dynamically changing, and uncertainty remains with respect to how these changes will affect the potential of these regions to provide food and fodder resources or how they will affect the biosphere–atmosphere exchange of CO2. In this study, we investigate the capacity of a process-based biogeochemical model, LandscapeDNDC, to simulate net ecosystem exchange (NEE) and aboveground biomass of typical managed and natural Sahelian and Sudanian savanna ecosystems. In order to improve the simulation of phenology, we introduced soil-water availability as a common driver of foliage development and productivity for all of these systems. The new approach was tested by using a sample of sites (calibration sites) that provided NEE from flux tower observations as well as leaf area index data from satellite images (MODIS, MODerate resolution Imaging Spectroradiometer). For assessing the simulation accuracy, we applied the calibrated model to 42 additional sites (validation sites) across West Africa for which measured aboveground biomass data were available. The model showed good performance regarding biomass of crops, grass, or trees, yielding correlation coefficients of 0.82, 0.94, and 0.77 and root-mean-square errors of 0.15, 0.22, and 0.12 kg m−2, respectively. The simulations indicate aboveground carbon stocks of up to 0.17, 0.33, and 0.54 kg C ha−1 m−2 for agricultural, savanna grasslands, and savanna mixed tree–grassland sites, respectively. Carbon stocks and exchange rates were particularly correlated with the abundance of trees, and grass biomass and crop yields were higher under more humid climatic conditions. Our study shows the capability of LandscapeDNDC to accurately simulate carbon balances in natural and agricultural ecosystems in semiarid West Africa under a wide range of conditions; thus, the model could be used to assess the impact of land-use and climate change on the regional biomass productivity.

Este ensayo propone una relectura de lo que ha sido el “ordenamiento del territorio” como actividad de control y organización de las actividades humanas en el espacio por el Estado capitalista moderno. Esta nueva lectura se hace a la luz de lo que se ha llamado la Geografía Humanista que plantea nuevos interrogantes a la relación entre los territorios y sus sociedades, que no fueron tomados en cuenta por el pasado en los ensayos de ordenamiento en diversos países. La intención de este ensayo es entonces, la de generar un debate sobre el sentido mismo del ordenamiento y sus formas de aplicarse, confrontando posiciones epistemológicas diversas sino adversas.

The leaf area index of Sahelian rangelands and related variables such as the vegetation cover fraction, the fraction of absorbed photosynthetically active radiation and the clumping index were measured between 2005 and 2017 in the Gourma region of northern Mali. These variables, known as climate essential variables, were derived from the acquisition and the processing of hemispherical photographs taken along 1 km linear sampling transects for five contrasted canopies and one millet field. The same sampling protocol was applied in a seasonally inundated Acacia open forest, along a 0.5 km transect, by taking photographs of the understorey and the tree canopy. These observations collected over more than a decade, in a remote and not very accessible region, provide a relevant and unique data set that can be used for a better understanding of the Sahelian vegetation response to the current rainfall changes. The collected data can also be used for satellite product evaluation and land surface model development and validation. This paper aims to present the field work that was carried out during 13 successive rainy seasons, the measured vegetation variables, and the associated open database. Finally, a few examples of data use are shown. DOI of the referenced data set: https://doi.org/10.17178/AMMA-CATCH.CE.Veg_Gh.

Presentación del Tema Central.

El crecimiento de la ciudad difusa a partir del imaginario suburbano que ha colonizado la vida moderna ha provocado una disminución radical de la vida urbana. Existen otros modelos que corresponden a imaginarios de resistencia a ese modelo colonizador: se trata de la gentrificación o elitización y del resurgimiento de la residencia en altura, que llamamos la ciudad de las torres de cristal. En la última parte del ensayo, se plantea que los imaginarios de resistencia pueden ser realizables si parten de las prácticas cotidianas, y tender a volverse las nuevas utopías urbanas del siglo XXI

Pastoral livestock is defined as a reproduction-oriented, grazing-based familial livestock system with community-managed resources. Pastoral breeders differ from one another in the diversity of species and breeds raised, the size and management of herds and the extent of their regional mobility. The social, economic and environmental weight of pastoralist livestock in West and Central sub-Saharan Africa is evoked together with its imputation of environmental degradation. Global changes faced by pastoral livestock are sorted out by domains, climatic and societal, and by time scales, short or long. The incriminated impacts of livestock on ecosystems are assessed in the short and long terms. The functions of pastoral breeding already affected by global changes whether climatic or societal are analyzed. The capacity of two alternative livestock breeding systems, ranching and stall-feeding, to respond to these constraints is reviewed. Finally, pastoral breeding has been recognized as being able to adapt best to long-term climate change and to short- and long-term societal changes, provided that national and international investments are made. Civil security must be restored and pastoralists’ access to water and fodder resources must be secured. Professional organizations and associations should be empowered to negotiate grazing rights, and their skills should be enhanced. There is the need to complete, rehabilitate and manage hydraulic and veterinary infrastructures, but also to invest significantly in adapted health, education and communication infrastructures in long-neglected pastoral areas.

Multi-purpose Faidherbia albida trees represent a vital component of agroforestry parklands in West Africa as they provide resources (fodder for livestock, fruits and firewood) and support water lifting and nutrient recycling for cropping. Faidherbia albida trees are characterized by their inverse phenology, growing leaf flowers and pods during the dry season, thereby providing fodder and shedding leaves during the wet season, which minimizes competition with pastures and crops for resources. Multi-spectral and multi-temporal satellite systems and novel computational methods open new doors for classifying single trees and identifying species. This study used a Multi-Layer Perception feedforward artificial neural network to classify pixels covered by Faidherbia albida canopies from Sentinel-2 time series in Senegal, West Africa. To better discriminate the Faidherbia albida signal from the background, monthly images from vegetation indices were used to form relevant variables for the model. We found that NDI54/NDVI from the period covering onset of leaf senescence (February) until end of senescence (leaf-off in June) to be the most important, resulting in a high precision and recall rate of 0.91 and 0.85. We compared our result with a potential Faidherbia albida occurrence map derived by empirical modelling of the species ecology, which deviates notably from the actual species occurrence mapped by this study. We have shown that even small differences in dry season leaf phenology can be used to distinguish tree species. The Faidherbia albida distribution maps, as provided here, will be key in managing farmlands in drylands, helping to optimize economic and ecological services from both tree and crop products.

Le 27 octobre 2016 s’est tenu à l’Université libre de Bruxelles un colloque qui avait pour titre « Interdisciplinarité : discours et réalités ». Il avait été précédé d’une enquête auprès de chercheurs francophones sur leur pratique effective à cet égard. Les 104 réponses collectées ont été traitées de façon approfondie et les résultats, situés dans l’état de l’art relatif aux enquêtes sur l’interdisciplinarité, ont été présentés pendant ce colloque. En outre, des orateurs internationaux ont partagé leur expérience dans différents domaines lors de cette journée. L’un des enseignements de ces nombreux échanges est qu’il existe aujourd’hui une pratique riche et diversifiée, qui contraste quelque peu avec l’image de difficulté souvent associée à l’interdisciplinarité. Cet article expose ces résultats et y ajoute des analyses et des propositions qui découlent de ces échanges. La journée était organisée dans le cadre des séminaires Prigogine « Penser la science ».

Many activities towards plants are directly related to environmental crisis issues. However, our actions towards plants are little theorized in philosophy and ethics. After a brief presentation of the history, state of the art, and current issues of plant ethics, I critically illustrate how the theoretical threads of current ethics should be clarified, and, more importantly, contextualised, to promote the application of concrete measures. Particular attention is paid to the ethics of plant flourishing as applied to different fields and types of plants. The treatment of wild and ornamental plants is, thus, explicitly distinguished from that of improved agricultural varieties, themselves distinguishable according to modes of cultivation. I thus propose and discuss several recommendations and concrete courses of action to promote an ethics of plants, while pointing out its limitations.

In recent decades, the Sahel has witnessed a paradoxical increase in surface water despite a general precipitation decline. This phenomenon, commonly referred to as the Sahelian paradox, is not completely understood yet. The role of cropland expansion due to the increasing food demand by a growing population has been often put forward to explain this situation for the cultivated Sahel. However, this hypothesis does not hold in pastoral areas where the same phenomenon is observed. Several other processes, such as the degradation of natural vegetation following the major droughts of the 1970s and the 1980s, the development of crusted topsoils, the intensification of the rainfall regime and the development of the drainage network, have been suggested to account for this situation. In this paper, a modeling approach is proposed to explore, quantify and rank different processes that could be at play in pastoral Sahel. The kinematic runoff and erosion model (KINEROS-2) is applied to the Agoufou watershed (245 km2), in the Gourma region in Mali, which underwent a significant increase of surface runoff during the last 60 years. Two periods are simulated, the past case (1960–1975) preceding the Sahelian drought and the present case (2000–2015). Surface hydrology and land cover characteristics for these two periods are derived by the analysis of aerial photographs, available in 1956, and high-resolution remote sensing images in 2011. The major changes identified are (1) a partial crusting of isolated dunes, (2) an increase of drainage network density, (3) a marked decrease in vegetation with the nonrecovery of tiger bush and vegetation growing on shallow sandy soils, and (4) important changes in soil properties with the apparition of impervious soils instead of shallow sandy soil. The KINEROS-2 model was parameterized to simulate these changes in combination or independently. The results obtained by this model display a significant increase in annual discharge between the past and the present case (p value 6 m3 (2.1 mm yr−1) and 3.29 × 106 m3 (13.4 mm yr−1) for past and present, respectively. Changes in soil properties and vegetation cover (tiger bush thickets and grassland on shallow sandy soil) are found to be the main factors causing this increase of simulated runoff, with the drainage network development contributing to a lesser extent but with a positive feedback. These results shed a new light on the Sahelian paradox phenomenon in the absence of land use change and call for further tests in other areas and/or with other models. The synergetic processes highlighted here could play a role in other Sahelian watersheds where runoff increase has been also observed.

Dedica-se este artigo à explicação da trajetória das duas novas vertentes da Geografia Humana. A primeira, marcada pelo racionalismo cartesiano. A segunda, por o que podemos englobar na proposta de uma “Geografia Sensible”. Estas trajetórias divergentes não são recentes, se vinculando a personagens e obras dos fundadores da Geogarfia moderna, e se consolidaram, com cronologias distintas, ao longo do século XX.

Background and study aims Endoscopic full-thickness resection (EFTR) is used to achieve R0 resection in difficult situations and as a way to overcome the limitations of endoscopic submucosal dissection. Multiple techniques have been described but adequate tools are still under evaluation. In this study, we evaluated the safety and feasibility of non-exposed endoscopic full-thickness resection using a novel endoscopic suturing device. Materials and methods Full-thickness resections of gastric predetermined lesions were performed on five pigs using the Endomina platform. After creating virtual lesion > 20 mm, sutures were placed around it using this triangulation platform. After tightening the knots, the bulging lesion, internalized into the gastric lumen, was cut with a needle knife. Results R0 resections of large lesions (42 to 60 mm) were achieved in all cases. One perforation occurred and prompted us to improve the procedure by shortening the sutures for more maneuverability and reinforcing the suture line before section. Procedure duration dropped by 50 % between the first case and the fourth case. Histological analysis confirmed successful full-thickness resection of all resected specimens. Conclusion EFTR using this triangulation platform seems feasible for lesions > 20 mm. Additional possible improvements were identified to simplify the procedure before moving to human trials.

The detection of water contamination with Legionella pneumophila is of critical importance to manufacturers of water processing equipment and public health entities dealing with water networks and distribution systems. Detection methods based on polymerase chain reaction or biosensor technologies require preconcentration steps to achieve attractive sensitivity levels. Preconcentration must also be included in protocols of automated collection of water samples by systems designed for quasi-continuous monitoring of remotely located water reservoirs for the presence of L. pneumophila. We designed and characterized a water sampling module for filtration and backwashing intended for analysis of low-to-medium contaminated water, typically with L. pneumophila bacteria not exceeding 50 colony-forming units per milliliter. The concentration factors of 10× and 21× were achieved with 0.22 and 0.45 µm filters, respectively, for samples of bacteria prepared in clean saline solutions. However, a 5× concentration factor was achieved with 0.45 µm filters for a heavily contaminated or turbid water typical of some industrial water samples.

L’évaluation produit des effets, désirés ou non, sur la recherche, ses orientations et ses résultats. Dans le cadre des séminaires Ilya Prigogine « Penser la science » à l’Université libre de Bruxelles, deux journées ont été consacrées à ce thème. La première a réalisé un état des lieux de la question, en étudiant les effets standardisants des indicateurs et des classements et en s’interrogeant sur le statut des chercheurs dans un contexte de compétition et sous-financement. La seconde journée a envisagé des propositions alternatives : valoriser les formes d’intelligence collective, adapter les indicateurs aux disciplines, repenser l’utilité et la responsabilité face aux résultats, récompenser la prise de risque, retourner à des démarches qualitatives… Loin de critiquer la notion d’évaluation per se, ces pistes appellent à des formes d’évaluation plus démocratiques, transparentes et contradictoires.

West Africa is a region in fast transition from climate, demography, and land use perspectives. In this context, the African Monsoon Multidisciplinary Analysis (AMMA)–Couplage de l’Atmosphère Tropicale et du Cycle eco-Hydrologique (CATCH) long-term regional observatory was developed to monitor the impacts of global change on the critical zone of West Africa and to better understand its current and future dynamics. The observatory is organized into three thematic axes, which drive the observation and instrumentation strategy: (i) analyze the long-term evolution of eco-hydrosystems from a regional perspective; (ii) better understand critical zone processes and their variability; and (iii) meet socioeconomic and development needs. To achieve these goals, the observatory has gathered data since 1990 from four densely instrumented mesoscale sites (∼10 km each), located at different latitudes (Benin, Niger, Mali, and Senegal) so as to sample the sharp eco-climatic gradient that is characteristic of the region. Simultaneous monitoring of the vegetation cover and of various components of the water balance at these four sites has provided new insights into the seemingly paradoxical eco-hydrological changes observed in the Sahel during the last decades: groundwater recharge and/or runoff intensification despite rainfall deficit and subsequent re-greening with still increasing runoff. Hydrological processes and the role of certain key landscape features are highlighted, as well as the importance of an appropriate description of soil and subsoil characteristics. Applications of these scientific results for sustainable development issues are proposed. Finally, detecting and attributing eco-hydrological changes and identifying possible regime shifts in the hydrologic cycle are the next challenges that need to be faced.

This work is an attempt to provide seasonal variation of biogenic NO emission fluxes in a Sahelian rangeland in Mali (Agoufou, 15.34° N, 1.48° W) for years 2004, 2005, 2006, 2007 and 2008. Indeed, NO is one of the most important precursors for tropospheric ozone, and previous studies have shown that arid areas potentially display significant NO emissions (due to both biotic and abiotic processes). Previous campaigns in the Sahel suggest that the contribution of this region in emitting NO is no longer considered as negligible. However, very few data are available in this region, therefore this study focuses on model development. The link between NO production in the soil and NO release to the atmosphere is investigated in this modelling study, by taking into account vegetation litter production and degradation, microbial processes in the soil, emission fluxes, and environmental variables influencing these processes, using a coupled vegetation–litter decomposition–emission model. This model includes the Sahelian Transpiration Evaporation and Productivity (STEP) model for the simulation of herbaceous, tree leaf and faecal masses, the GENDEC model (GENeral DEComposition) for the simulation of the buried litter decomposition and microbial dynamics, and the NO emission model (NOFlux) for the simulation of the NO release to the atmosphere. Physical parameters (soil moisture and temperature, wind speed, sand percentage) which affect substrate diffusion and oxygen supply in the soil and influence the microbial activity, and biogeochemical parameters (pH and fertilization rate related to N content) are necessary to simulate the NO flux. The reliability of the simulated parameters is checked, in order to assess the robustness of the simulated NO flux. Simulated yearly average of NO flux ranges from 2.09 to 3.04 ng(N) m−2 s−1 (0.66 to 0.96 kg(N) ha−1 yr−1), and wet season average ranges from 3.36 to 5.48 ng(N) m−2 s−1 (1.06 to 1.73 kg(N) ha−1 yr−1). These results are of the same order as previous measurements made in several sites where the vegetation and the soil are comparable to the ones in Agoufou. This coupled vegetation–litter decomposition–emission model could be generalized at the scale of the Sahel region, and provide information where few data are available.

Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna–forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna–forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three continents coexistence was found to be confined to a well-defined edaphic–climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands. Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna) data set. Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands.

Les volumes de lait de vache traits ont été mesurés tous les quinze jours sur une année chez 300 petits exploitants agro­pastoraux de la zone semi-aride du Sahel, dans la commune de Dantiandou au Niger. Les effectifs de vaches − adultes, en lactation et effectivement traites le matin et/ou le soir − ont été systématiquement enregistrés, ainsi que des informations sur la gestion de la pâture, la supplémentation alimentaire des vaches, et la consommation, la transformation du lait et la vente des produits laitiers. En outre, les carrières de reproduc­tion des 334 vaches ont été documentées par enquête rétros­pective. Le volume moyen par jour d’une traite a été de 0,82 ± 0,45 L. Il n’a pas été significativement différent entre la traite du matin et celle du soir, ni entre les saisons, ni entre les éle­vages. Cependant, les volumes totaux de lait trait par élevage, dont la moyenne annuelle a été de 507 ± 362 L, ont fortement varié en fonction des saisons et des élevages. En moyenne, ils ont été plus élevés dans les élevages des campements peuls récemment sédentarisés (624 ± 377 L) que dans ceux des éle­vages villageois djerma (352 ± 275 L). Cet écart était princi­palement dû à un effectif de vaches plus important dans les campements (7,1 ± 5,3 vs 4,3 ± 4,0), bien que la proportion de vaches en lactation y ait été plus faible (57 %) que dans les troupeaux villageois (73 %). Les résultats ont montré qu’une meilleure gestion par les agroéleveurs des campements avec des traites moins fréquentes, un recours plus fréquent à la pâture de nuit, à la transhumance et à une supplémentation alimentaire régulière ont contribué à améliorer l’état d’en­graissement des vaches et leurs performances reproductives. Malgré ces rendements laitiers modestes, la valeur monétaire du lait trait a représenté 16 % des revenus agricoles et non-agricoles des ménages des campements, et 7 % de ceux des villages. Les produits laitiers étaient largement consacrés à la consommation familiale : 78 % dans les campements et 84 % dans les villages.

Rain Use Efficiency (RUE), defined as Aboveground Net Primary Production (ANPP) divided by rainfall, is increasingly used to diagnose land degradation. Yet, the outcome of RUE monitoring has been much debated since opposite results were found about land degradation in the Sahel region. The debate is fueled by methodological issues, especially when using satellite remote sensing data to estimate ANPP, and by differences in the ecological interpretation. An alternative method which solves part of these issues relies on the residuals of ANPP regressed against rainfall (“ANPP residuals”). In this paper, we use long-term field observations of herbaceous vegetation mass collected in the Gourma region in Mali together with remote sensing data (GIMMS-3g Normalized Difference Vegetation Index) to estimate ANPP, RUE, and the ANPP residuals, over the period 1984–2010. The residuals as well as RUE do not reveal any trend over time over the Gourma region, implying that vegetation is resilient over that period, when data are aggregated at the Gourma scale. We find no conflict between field-derived and satellite-derived results in terms of trends. The nature (linearity) of the ANPP/rainfall relationship is investigated and is found to have no impact on the RUE and residuals interpretation. However, at odds with a stable RUE, an increased run-off coefficient has been observed in the area over the same period, pointing towards land degradation. The divergence of these two indicators of ecosystem resilience (stable RUE) and land degradation (increasing run-off coefficient) is referred to as the “second Sahelian paradox”. When shallow soils and deep soils are examined separately, high resilience is diagnosed on the deep soil sites. However, some of the shallow soils show signs of degradation, being characterized by decreasing vegetation cover and increasing run-off coefficient. Such results show that contrasted changes may co-exist within a region where a strong overall re-greening pattern is observed, highlighting that both the scale of observations and the scale of the processes have to be considered when performing assessments of vegetation changes and land degradation.

The Sahel (a semi-arid fringe south of the Sahara) experienced a long and prolonged drought from the 1970s to the mid-1990s, with a few extremely severe episodes that strongly affected ecosystems and societies. Long-term observations showed that surface runoff increased during this period, despite the rainfall deficit. This paradox stems from the soil degradation that was induced by various factors, either directly linked to the drought (impact on vegetation cover), or, in places, to human practices (land clearing and cropping). Surface runoff is still increasing throughout the region, suggesting that Sahelian ecohydrosystems may have shifted to a new hydrological regime. In order to explore this issue, we have developed a simple system dynamics model incorporating vegetation–hydrology interactions and representing in a lumped way the first order processes occurring at the hillslope scale and the annual timestep. Long term observations on a pilot site in northern Mali were used to constrain the model and define an ensemble of plausible simulations. The model successfully reproduced the vegetation collapse and the runoff increase observed over the last 60 years. Our results confirmed that the system presents two alternative states and that during the drought it shifted from a high-vegetation/low-runoff regime to the alternative low-vegetation/high-runoff one, where it has remained trapped until now. We showed that the mean annual rainfall deficit was sufficient to explain the shift. According to the model, vegetation recovery and runoff reduction are possible in this system, but the conditions in which they could occur remain uncertain as the model was only constrained by observations over the collapse trajectory. The study shows that the system is also sensitive to the interannual and decadal variability of rainfall, and that larger variability leads to higher runoff. Both mean rainfall and rainfall variability may increase in central Sahel under climate change, leading to antagonist effects on the system, which makes its resilience uncertain.

The problem of diagnostic checking is tackled from the perspective of the subspace methods. Two statistics are presented and their asymptotic distributions are derived under the null hypothesis. The procedures are devised to deal with univariate and multivariate processes, are flexible and able to separately check regular and seasonal correlations. The performance in finite samples of the proposals is illustrated via Monte Carlo simulations and two examples with real data.

Gastrointestinal stimulator implants have recently shown positive results in helping obese patients lose weight. However, to place the implant, the patient currently needs to undergo an invasive surgical procedure. Our team is aiming for a less invasive procedure to stimulate the stomach with a gastrostimulator. Attempts covered fully endoscopic implantation and, more recently, we have focussed on a single incision laparoscopic procedure. Whatever the chosen implantation solution, the electronic design of the implant system shares many challenges. This paper covers the work achieved to meet these.

The potentialities of ENVISAT ASAR (Advanced Synthetic Aperture Radar) multi-angle data for mapping surface soil moisture (SSM) in Sahelian rangelands are investigated at medium scale (30 000 km2). The Wide Swath data are selected to take advantage of their high temporal repetitivity (about 8 days at the considered scale) associated to a moderate spatial resolution (150 m). In the continuity of previous studies conducted at a local scale in the same region, SSM maps are here processed over the whole AMMA Gourma mesoscale site at 1 km resolution scale. Overall, the generated maps are found to be in good agreement with field data, EPSAT-SG (Estimation des Pluies par SATellite – Second Generation) rainfall estimates and ERS (European Remote Sensing) Wind Scatterometer (WSC) SSM products. The present study shows that the spatial pattern of SSM can be realistically estimated at a kilometric scale. The resulting SSM maps are expected to provide valuable information for initialisation of land surface models and the estimation of the spatial distribution of radiative fluxes. Particularly, SSM maps could help to desaggregate low-resolution products such as those derived from WSC data.

In the West African Sahel, two paradoxical hydrological behaviors have occurred during the last five decades. The first paradox was observed during the 1968–1990s ‘Great Drought’ period, during which runoff significantly increased. The second paradox appeared during the subsequent period of rainfall recovery (i.e., since the 1990s), during which the runoff coefficient continued to increase despite the general re-greening of the Sahel. This paper reviews and synthesizes the literature on the drivers of these paradoxical behaviors, focusing on recent works in the West African Sahelo/Sudanian strip, and upscaling the hydrological processes through an analysis of recent data from two representative areas of this region. This paper helps better determine the respective roles played by Land Use/Land Cover Changes (LULCC), the evolution of rainfall intensity and the occurrence of extreme rainfall events in these hydrological paradoxes. Both the literature review and recent data converge in indicating that the first Sahelian hydrological paradox was mostly driven by LULCC, while the second paradox has been caused by both LULCC and climate evolution, mainly the recent increase in rainfall intensity.

Changes in the flooded area of ponds in the Gourma region from 1950 to present are studied by remote sensing, in the general context of the current multi-decennial Sahel drought. The seasonal and interannual variations of the areas covered by surface water are assessed using multi-date and multi-sensor satellite images (SPOT, FORMOSAT, LANDSAT-MSS, –TM, and -ETM, CORONA, and MODIS) and aerial photographs (IGN). Water body classification is adapted to each type of spectral resolution, with or without a middle-infrared band, and each spatial resolution, using linear unmixing for mixed pixels of MODIS data. The high-frequency MODIS data document the seasonal cycle of flooded areas, with an abrupt rise early in wet season and a progressive decrease in the dry season. They also provide a base to study the inter-annual variability of the flooded areas, with sharp contrasts between dry years such as 2004 (low and early maximal area) and wetter years such as 2001 and 2002 (respectively high and late maximal area).The highest flooded area reached annually greatly depends on the volume, intensity and timing of rain events. However, the overall reduction by 20% of annual rains during the last 40 years is concomitant with an apparently paradoxical large increase in the area of surface water, starting from the 1970's and accelerating in the mid 1980's. Spectacular for the two study cases of Agoufou and Ebang Mallam, for which time series covering the 1954 to present period exist, this increase is also diagnosed at the regional scale from LANDSAT data spanning 1972–2007. It reaches 108% between September 1975 and 2002 for 91 ponds identified in central Gourma. Ponds with turbid waters and no aquatic vegetation are mostly responsible for this increase, more pronounced in the centre and north of the study zone. Possible causes of the differential changes in flooded areas are discussed in relation with the specifics in topography, soil texture and vegetation cover over the watersheds that feed each of the ponds. Changes in rain pattern and in ponds sedimentation are ruled out, and the impact of changes in land use, limited in the area, is found secondary, as opposed to what has often been advocated for in southern Sahel. Instead, major responsibility is attributed to increased runoff triggered by the lasting impact of the 1970–1980's droughts on the vegetation and on the runoff system over the shallow soils prevailing over a third of the landscape.

En este artículo se presentan y analizan los índices del costo de la vida de tres ciudades españolas, Palencia, Madrid y Sevilla, que cubren el periodo 1680-1800. Las contabilidades de diversos hospitales, colegios e instituciones benéficas han constituido la fuente principal para la elaboración de los referidos índices. En las tres urbes objeto de estudio los precios se comportaron de una manera bastante similar: todos los índices comparten tendencia y ciclo común y presentan un grado significativo de relación lineal entre sus tasas logarítmicas de variación. Sin embargo, también se observan diferencias significativas en los movimientos a corto y largo plazos de los precios: por un lado, las tensiones inflacionistas de la segunda mitad del siglo XVIII fueron más intensas en Palencia y en Sevilla que en la capital de la monarquía hispánica; por otro lado, en Madrid las fluctuaciones interanuales del costo de la vida fueron menos violentas que en Palencia y Sevilla. A nuestro juicio, hay evidencias que apuntan a que la singularidad de Madrid obedeció, ante todo, a la mayor cantidad de recursos que las instituciones públicas dedicaron en dicha urbe a la protección de los consumidores.In this article we present and analyze new cost of living indexes for three relevant Spanish urban centers that cover from 1680 to 1800. The accounts of several hospital, schools and charitable institutions have been used as main sources to construct these indexes. The three indexes behave in a fairly similar way. They share common trends and cycles and show a significant linear relationship among their logarithmic rates of variation. Nonetheless, some substantial differences in the short and the long term movement of prices may be observed as well. On the one hand, inflationary tensions in the second half of the eighteenth century were more intense in Palencia and Seville than in Madrid. On the other hand, yearly fluctuations in the cost of living were lower in Madrid than in Palencia and Seville. In our opinion, there is evidence suggesting that these differences were mainly due to the greater amount of resources devoted by both council and monarchy to protect consumer from rising prices in Madrid.

Este trabajo tiene dos objetivos interrelacionados: el primero es mostrar, a partir de un caso empírico, que la posibilidad de mutilar la complejidad del fenómeno estudiado con el tipo de análisis seguido, no sólo es un problema conceptual, sino también relativo al tipo de proceso de producción de la información empírica. El segundo objetivo es presentar algunas de las múltiples facetas de esa complejidad –sobre todo las no esperadas– en un fragmento de la vida social de la periferia metropolitana excluida del oriente de la ciudad de México. En el abordaje de este tema integramos aspectos instrumentales y subjetivos, pero ambos considerados espacialmente.

Partiendo de la necesidad de un regreso sobre el concepto de imaginarios, este artículo repasa, en primer lugar, las diversas aportaciones a la genealogía del concepto que podemos extraer de las ciencias sociales y las humanidades. Enseguida nos interrogamos sobre la relación entre imaginarios y espacio, demostrando su fuerte articulación desde la misma conceptualización de los imaginarios. En la tercera parte del texto, se hace un breve repaso de los diversos estudios existentes sobre imaginarios urbanos y en particular, se diferencian tres líneas: una dedicada a las prácticas, otra centrada en las representaciones y una tercera que busca la articulación de las prácticas con la experiencia espacial y el espacio vivido. Temas relevantes que surgen de las tres líneas son la pérdida de la ciudad, el impacto de la modernidad sobre la vida urbana, los nuevos estilos de vida ligados a la posmodernidad y, finalmente, el miedo y la falta de seguridad. Se concluye sobre la necesidad de abordar los imaginarios desde perspectivas de multirre fe rendas disciplinarias, sin menospreciar la dimensión material de la ciudadFrom a starting point of the need to return to the concept of maginaries, this paper first reviews the various contributions to the genealogy of this concept that can he extractedfrom the social sciences and humanities. The paper then questions the relationship between imaginaries and space, revealing the close articulation between them from the very same conceptualization of imaginaries. Finally, the paper offers a brief review of the various studies of urban imaginaries, providing evidence of the differences between three approaches: the first dedicated to practices, the second representations and the third on the search for the articulation between practices and spatial experiences and lived spaces. Important themes that arise from these three approaches are the loss of the city, the impact of modernity on urban life, the new lifestyles linked to postmodernity and, finally, fear and the lack of security. The conclusions relate to perspectives from multiple disciplinary references, without underestimating the material dimensions of the city

Proponemos un nuevo procedimiento para detectar raíces unitarias basado en métodos de subespacios. Su planteamiento comporta tres aspectos fundamentales. Primero, la misma metodología se puede aplicar a series individuales o a vectores de series temporales. Segundo, utiliza una familia flexible de criterios de información, cuyas funciones de pérdida se pueden adaptar a las propiedades estadísticas de los datos. Finalmente, no requiere especificar un proceso estocástico para las series analizadas. Se demuestra la consistencia del método y los ejercicios de simulación revelan buenas propiedades en muestras finitas. Además, su aplicación práctica se ilustra mediante el análisis de varias series reales.

We propose a new procedure to detect unit roots based on subspace methods. It has three main original aspects. First, the same method can be applied to single or multiple time series. Second, it uses a flexible family of information criteria, which loss functions can be adapted to the statistical properties of the data. Last, it does not require the specification of a stochastic process for the series analyzed. This procedure is consistent and a simulation exercise shows that it has good finite sample properties. Its application is illustrated with the analysis of several real time series.Proponemos un nuevo procedimiento para detectar raíces unitarias basado en métodos de subespacios. Su planteamiento comporta tres aspectos fundamentales. Primero, la misma metodología se puede aplicar a series individuales o a vectores de series temporales. Segundo, utiliza una familia flexible de criterios de información, cuyas funciones de pérdida se pueden adaptar a las propiedades estadísticas de los datos. Finalmente, no requiere especificar un proceso estocástico para las series analizadas. Se demuestra la consistencia del método y los ejercicios de simulación revelan buenas propiedades en muestras finitas. Además, su aplicación práctica se ilustra mediante el análisis de varias series reales.

Este trabajo presenta una serie de reflexión sobre el concepto del trasnacionalismo, desde una perspectiva espacio-temporal. En una primera parte del trabajo, se presentan los modelos societales de tiempo, desde la ausencia de concepción del tiempo de las sociedades primitivas, pasando por el modelo cíclico de las tradicionales, línea de la modernidad, hasta la concepción posmoderna del tiempo y el espacio. Posteriomente, se integra la dimensión espacial, para preguntarse, en la tercera parte, cómo se articulan estas concepciones espaciotemporales en situaciones de trasnacionalismo, para concluir que los migrantes en situación trasnacional tienen la capacidad de jugar con diversas concepciones para construir su propio modelo espacio-temporal.

Proponemos un nuevo procedimiento para detectar raíces unitarias basado en métodos de subespacios. Su planteamiento comporta tres aspectos fundamentales. Primero, la misma metodología se puede aplicar a series individuales o a vectores de series temporales. Segundo, utiliza una familia flexible de criterios de información, cuyas funciones de pérdida se pueden adaptar a las propiedades estadísticas de los datos. Finalmente, no requiere especificar un proceso estocástico para las series analizadas. Se demuestra la consistencia del método y los ejercicios de simulación revelan buenas propiedades en muestras finitas. Además, su aplicación práctica se ilustra mediante el análisis de varias series reales.We propose a new procedure to detect unit roots based on subspace methods. It has three main original aspects. First, the same method can be applied to single or multiple time series. Second, it uses a flexible family of information criteria, which loss functions can be adapted to the statistical properties of the data. Last, it does not require the specification of a stochastic process for the series analyzed. This procedure is consistent and a simulation exercise shows that it has good finite sample properties. Its application is illustrated with the analysis of several real time series

Los cambios recientes en las ciudades generan numerosas interpretaciones muy diferentes entre sí. Pocos autores, sin embargo, enfrentan una pregunta fundamental: ¿estamos todavía frente a lo que tradicionalmente se ha llamado “ciudad”? Este artículo se orienta a interrogar la dimensión ontológica de la ciudad. Para ello remite a tres dimensiones: lo laberíntico, lo fortuito y lo fugaz, cuya articulación integra la esencia de lo urbano. No todo lo urbanizado actual responde a este modelo, y es a planteamientos como el de Louis Wirth sobre el modo de vida urbano que convendría remitir, entre otros, para replantear las políticas urbanas.

Urban studies in Mexico began to acquire importance in the middle of the seventies following successive stages during which the fieldwork has been differently approached and appreciated. The present paper examines these stages and highlights the different conceptions of the fieldwork. The author concludes that at the present stage we are witnessing a come back of the fieldwork due to the new approaches used by the urban studies, more oriented to anthrophology and comprehensive sociology that it was the case in the past.

Los cambios en la economía mexicana ocurridos durante los quince últimos años han tenido profundas repercusiones en la organización del territorio a escala nacional y regional; trastornaron también las economías urbanas: un fuerte crecimiento demográfico y económico de las ciudades medias, la reestructuración económicas de las metrópolis son algunas de sus consecuencias. Dichas transformaciones dejan también entrever la posibilidad de profundas modificaciones de los sistemas sociales y, entre otros, de las percepciones y de los usos de la ciudad por las comunidades. Este artículo va en dos direcciones: la primera se orientará a analizar las transformaciones económicas que han reconfigurado la ciudad de México. En la segunda parte del ensayo trataremos las transformaciones en la estructura urbana de la capital, con relación a las grandes tendencias anteriormente expuestas: los nuevos complejos comerciales, la segregación de los barrios, la aparición de espacios "posmodernos", etc.The changes in the Mexican economy during the last fifteen years have had profound effects on territorial organization, both on a national and regional scale; it also upset urban economies: a strong demographical and economic growth of medium size cities, and a restructuring of the metropolitan economies are some of its consequences. Such transformations allow us to see, although not directly, the possibility of a modification of the social system and, among others, of the perceptions and usage of the city by communities. This article is divided into two sections: the first one will analyze the economic transformations that have reconfigured Mexico City. The second part of this essay will deal with the transformations that have occurred in the urban structure of the capital in relation to large trends that have been dealt with before: new commercial compounds, neighborhood segregation, the coming of ‘post modern’ spaces, etc.

Walter Benjamin (1892-1940) ha sido uno de los investigadores más creativos de su generación, además de lo difícil que resulta ubicarlo en una línea, debido a la vastedad, intensidad y variedad de una obra que sólo llegó entera al público gracias a la recopilación de las Gesammelte Schriften, realizada por Rolf Tiedemann durante los años sesenta y setenta. Si bien en la actualidad existe una moda benjaminiana, falta mucho por analizar, entre otros aspectos, lo referente a los textos o citas de los Pasajes de París, su obra magistral interrumpida por el suicidio. A través de diversas obras del autor, pero particularmente por medio de sus escritos sobre los pasajes parisinos, en este artículo se intenta reconstruir el abordaje metodológico propio de Benjamin, que se constituye en una especie de enfoque específico de la realidad, además de un compromiso sin debilidades con su tema, y también supone la adopción de una orientación central o "dirección única" de su trabajo. Benjamin propone diversos recursos metodológicos, que aclara a lo largo de su obra, tales como la imagen dialéctica, el recurso a los "desechos o harapos" de la sociedad, la valorización del análisis del objeto material para reconstruir épocas pasadas, etc. Su obra y su vida misma se constituyen así en un referente de primer orden para definir senderos de investigación en la actualidad.

Quantitative estimates of forage availability at the end of the growing season in rangelands are helpful for pastoral livestock managers and for local, national and regional stakeholders in natural resource management. For this reason, remote sensing data such as the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) have been widely used to assess Sahelian plant productivity for about 40 years. This study combines traditional FAPAR-based assessments with agrometeorological variables computed by the geospatial water balance program, GeoWRSI, using rainfall and potential evapotranspiration satellite gridded data to estimate the annual herbaceous yield in the semi-arid areas of Senegal. It showed that a machine-learning model combining FAPAR seasonal metrics with various agrometeorological data provided better estimations of the in situ annual herbaceous yield (R2 = 0.69; RMSE = 483 kg·DM/ha) than models based exclusively on FAPAR metrics (R2 = 0.63; RMSE = 550 kg·DM/ha) or agrometeorological variables (R2 = 0.55; RMSE = 585 kg·DM/ha). All the models provided reasonable outputs and showed a decrease in the mean annual yield with increasing latitude, together with an increase in relative inter-annual variation. In particular, the additional use of agrometeorological information mitigated the saturation effects that characterize the plant indices of areas with high plant productivity. In addition, the date of the onset of the growing season derived from smoothed FAPAR seasonal dynamics showed no significant relationship (0.05 p-level) with the annual herbaceous yield across the whole studied area. The date of the onset of rainfall however, was significantly related to the herbaceous yield and its inclusion in fodder biomass models could constitute a significant improvement in forecasting risks of a mass herbaceous deficit at an early stage of the year.

Les auteurs analysent la saisonnalité de la feuillaison de 28 espèces ligneuses sahéliennes afin de caractériser les disponibilités saisonnières en feuillage fourrager ainsi que leurs variations interannuelles. Pour chacune des espèces, des branchettes de même calibre ont été échantillonnées chaque mois entre 1979 et 1992, dans une ou plusieurs populations dont les sites sont répartis tout le long du gradient bioclimatique sahélien du Mali. Cinq groupes d'espèces ont été caractérisés par le régime saisonnier de leur feuillaison. Trois rassemblent des espèces caducifoliées distinguées entre elles par la durée de cette période; deux regroupent des espèces sempervirentes distinguées par la date de renouvellement du feuillage. Les variations de densité foliaire inter-sites et interannuelles sont quantifiées, leur écologie est étudiée par analyses de variance. On démontre ainsi que la densité maximale de feuillaison au cours de l'année dépend avant tout des infiltrations hydriques accumulées dans le sol au cours de l'année précédente. En conclusion, il est proposé de tenir compte de cette saisonnalité et de ces fluctuations interannuelles dans l'évaluation des ressources fourragères apportées par les plantes ligneuses et, plus généralement, dans toute quantification du rôle des ligneux dans l'écosystème sahélien.

En este artículo se presentan y analizan los índices del costo de la vida de tres ciudades españolas, Palencia, Madrid y Sevilla, que cubren el periodo 1680-1800. Las contabilidades de diversos hospitales, colegios e instituciones benéficas han constituido la fuente principal para la elaboración de los referidos índices. En las tres urbes objeto de estudio los precios se comportaron de una manera bastante similar: todos los índices comparten tendencia y ciclo común y presentan un grado significativo de relación lineal entre sus tasas logarítmicas de variación. Sin embargo, también se observan diferencias significativas en los movimientos a corto y largo plazos de los precios: por un lado, las tensiones inflacionistas de la segunda mitad del siglo XVIII fueron más intensas en Palencia y en Sevilla que en la capital de la monarquía hispánica; por otro lado, en Madrid las fluctuaciones interanuales del costo de la vida fueron menos violentas que en Palencia y Sevilla. A nuestro juicio, hay evidencias que apuntan a que la singularidad de Madrid obedeció, ante todo, a la mayor cantidad de recursos que las instituciones públicas dedicaron en dicha urbe a la protección de los consumidores.

El turismo sigue siendo un tema relativamente poco abordado por la geografía humana. Es a partir de los años sesenta, en la línea del trabajo seminal de Christaller, que empezó a desarrollarse un análisis más bien estructural del turismo. Este trataba de proveer de grandes modelos explicativos a la configuración espacial del proceso turístico. A partir de los sesenta, una corriente crítica se sumió a la anterior, pero aun desde perspectivas de pequeña escala. Es el giro cultural desde los ochenta, que empezó a cambiar los enfoques en la geografía humana, y para los estudiosos del turismo, provocó un giro importante hacia una “nueva geografía cultural del turismo” cuyas características, aportes y limitaciones se analizan en este trabajo.

Los cambios recientes en las ciudades generan numerosas interpretaciones muy diferentes entre sí. Pocos autores, sin embargo, enfrentan una pregunta fundamental: ¿estamos todavía frente a lo que tradicionalmente se ha llamado "ciudad"? Este artículo se orienta a interrogar la dimensión ontológica de la ciudad. Para ello remite a tres dimensiones: lo laberíntico, lo fortuito y lo fugaz, cuya articulación integra la esencia de lo urbano. No todo lo urbanizado actual responde a este modelo, y es a planteamientos como el de Louis Wirth sobre el modo de vida urbano que convendría remitir, entre otros, para replantear las políticas urbanas.