Pratiques paysannes d'exploitation des arbres et paysages forestiers dans le Haut Atlas central

Dans le Haut Atlas marocain, les sociétés rurales berbères ont mis en place des systèmes de gestion endogènes qui ont permis de maintenir la disponibilité des ressources forestières et pastorales sur le temps long, notamment parla pratique de l'agdal. Celle-ci correspond à l'instauration de mises en défens temporaires sur des territoires bien définis et l'élaboration de règles d'usages pour des ayants droit bien identifiés. Les modalités des règles et des pratiques d'usages qui en découlent ont des incidences directes sur les formes des arbres et la structure des peuplements forestiers. On assiste ainsi à un façonnage de paysages diversifiés au sein d'une forêt rurale qui répond à des modes de vie et des besoins qui intègrent production,conservation et gestion des aléas d'un milieu montagnard contraignant au sein de dimensions sociales, politiques et spirituelles propres aux sociétés locales qui les ont pensées

The influence of Saharan agro-pastoralism on the structure and dynamics of acacia stands

International audienceTrees play a crucial role in drylands, where they are often considered as keystone species for ecosystems and for local livelihoods. In particular in the Saharan region, Vachellia tortilis subsp. raddiana (ex. Acacia tortilis subsp. raddiana) are multipurpose acacia trees for people and contribute to the overall ecosystem functioning. Despite progress in research, acacia stands in this region are poorly documented and little is known on their interactions with human Saharan populations. On the basis of a multidisciplinary approach, the aim of this study was to assess the structure and dynamics of Saharan acacia stands in southwestern Morocco and the influence of human activities and practices. Interviews and participant observations were performed in two villages and individual acacia trees were measured in contrasting topography, microhabitat and land use situations. The acacia stands were located in cultivated and browsed areas where trees were used and shaped in the framework of human subsistence activities. In this context, the low-density acacia stands (4.8 trees/ha) showed high regeneration (47.8%) and recruitment rates, and low mortality (3.3%). Land use had more effect on stand structures than topography or microhabitat. Tree regeneration and density were especially high in cultivated areas. Most trees showed traces of pruning (60.3% of them) and debarking (33.9%), but with no correlation with tree mortality. Environmental and anthropogenic factors jointly contributed to the structure and dynamics of acacia stands, and no threat to their sustainability was observed. Even though further investigation would be required to better distinguish environmental and anthropogenic factors and to draw long-term conclusions, our results suggest that Saharan agro-pastoralism activities are not necessarily incompatible with acacia tree conservation, contrary to the commonly admitted postulate in Morocco

The multiple dimensions of rural forests : lessons from a comparative analysis

Rural forests are characterized by different levels of formal and nonformal appropriation by rural communities who have generally managed, shaped, or rebuilt these forest formations over many generations with refined local knowledge and practices related to their use and perpetuation. Rural forests are therefore social-ecological systems that contribute to ecosystem and landscapes configuration, definition of rural territories, and sustainability of local livelihoods. Although some studies have attempted to explain their specificities, in specific geographical and social contexts, their characteristics are not well defined as they encompass highly diversified situations. This lack of comprehension of the identity of rural forests is at the heart of the lack of dialogue between forestry policies and rural forest development. Our major aim is to identify universal characteristics of rural forests as well as specificities that can differentiate them. Eleven situations of rural forests were analyzed by means of detailed, harmonized monographs, from developing and developed countries, and localized within contrasting ecological environments (humid tropics, dry forests, temperate forests) and socio-economic and public policies contexts. Qualitative data were obtained through a common analytical framework and were encoded with an approach based on the collective appreciation of the group of researchers who developed case studies. These were pooled within a common analysis chart and were processed by means of multivariate analyses. Results were further discussed taking into consideration four major characteristics that emerged from this analysis, and which form the identity of rural forests. These are: 1) specific forest structures and levels of integration in agricultural matrices which are linked historically to overall agroecosystem approaches and practices, 2) a multiscale approach to domestication practices from landscape to individual trees inscribed in continuities between "nature" and "culture", natural processes and human techniques of control and transformation, 3) multiple uses of plant species which vary in relation to the commercial or noncommercial status of their products and a reversible nature of these use patterns accordingly, 4) the imbricate nature of rules of access and control between state and customary levels, and between individual and collective levels, requiring specific formal and informal arrangements. Typologies of rural forests can be drawn along each of these major characteristics and provide a reliable system to analyze and understand the functioning of rural forests. Forestry approaches in rural contexts, hence, need to consider variations along these major lines that form the identity cards of rural forests

Savoirs autochtones et développement

L'huile d'argan du Maroc, produite à partir d'un arbre géré séculairement par les populations locales au sein d'un écosystème forestier très domestiqué, a fait l'objet de nombreuses opérations de valorisation et de patrimonialisation. Partant de l'analyse des mobilisations par plusieurs catégories d'acteurs, des savoirs locaux relatifs à la gestion de l'arganier et de ses produits, nous discutons de la façon dont la confrontation des imaginaires, des cadres normatifs et des modèles de développement des uns et des autres ont conduit à se focaliser sur les savoirs liés à la production de l'huile en effaçant ceux de l'amont, moins visibles. Cela nous conduit à analyser comment des formes de reconnaissance des savoirs locaux peuvent conduire à séparer des connaissances interdépendantes, et induire des dynamiques sociocognitives et socioenvironnementales elles aussi dissociatives. Il importe alors d'évaluer l'impact que peuvent avoir ces mobilisations sélectives des savoirs sur les dynamiques et les résiliences des systèmes socioécologiques en présence

Factors influencing the age at onset in familial frontotemporal lobar dementia: Important weight of genetics

International audienceObjective: To quantify the effect of genetic factors and generations influencing the age at onset (AAO) in families with frontotemporal lobar dementia (FTD) due to C9ORF72 hexanucleotide repeat expansions and GRN mutations.Methods: We studied 504 affected individuals from 133 families with C9ORF72 repeat expansions and 90 FTD families with mutations in GRN, 2 major genes responsible for FTD and/or amyotrophic lateral sclerosis. Intrafamilial correlations of AAO were analyzed, and variance component methods were used for heritability estimates. Generational effects on hazard rates for AAO were assessed using mixed-effects Cox proportional hazard models.Results: A generational effect influencing AAO was detected in both C9ORF72 and GRN families. Nevertheless, the estimated proportion of AAO variance explained by genetic factors was high in FTD caused by C9ORF72 repeat expansions (44%; p = 1.10e-4), 62% when the AAO of dementia was specifically taken into account (p = 8.10e-5), and to a lesser degree in GRN families (26%; p = 0.17). Intrafamilial correlation analyses revealed a significant level of correlations in C9ORF72 families according to the degree of kinship. A pattern of intrafamilial correlations also suggested potential X-linked modifiers acting on AAO. Nonsignificant correlation values were observed in GRN families.Conclusions: Our results provide original evidence that genetic modifiers strongly influence the AAO in C9ORF72 carriers, while their effects seem to be weaker in GRN families. This constitutes a rational to search for genetic biomarkers, which could help to improve genetic counseling, patient care, and monitoring of therapeutic trials

Mediterranean land surfaces under global change : towards a roadmap for sustainable land use in Europe

Mediterranean forests are found in the Mediterranean basin, California, the South African Cape Province, South and southwestern Australia and parts of Central Chile. They represent 1.8 % of the world forest areas of which the vast majority is found in the Mediterranean basin, where historical and paleogeographic episodes, long-term human influence and geographical and climatic contrasts have created ecosystemic diversity and heterogeneity. Even if evergreen is dominant, deciduous trees are also represented, with different forest types including dense stands with a closed canopy (forests sensu stricto) and pre-forestal or pre-steppic structures with lower trees density and height. The Mediterranean basin is also a hot spot of forest species and genetic diversity, with 290 woody species versus only 135 for non-Mediterranean Europe. However, the characteristics of the Mediterranean area (long-standing anthropogenic pressure, significant current human activity and broad biodiversity) make it one of the world's regions most threatened by current changes. Four examples of Mediterranean forest types, present in south and north of the Mediterranean basin and more or less threatened, are developed in order to show that linking "hard sciences" and humanities and social sciences is necessary to understand these complex ecosystems. We show also that these forests, in spite of specific climatic constraints, can also be healthy and productive and play a major ecological and social role. Furthermore, even if the current human activity and global change constitute a risk for these exceptional ecosystems, Mediterranean forests represent a great asset and opportunities for the future of the Mediterranean basin