Browsing by Autor "Mohamed Alifriqui"

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Key concepts and a world‐wide look at plant recruitment networks
(Wiley, 2024) Julio M. Alcántara; Miguel Verdú; José Luis Hernando Garrido; Alicia Montesinos‐Navarro; Marcelo A. Aizen; Mohamed Alifriqui; David Allen; Ali A. Al‐Namazi; Cristina Armas; Jesús M. Bastida
Plant-plant interactions are major determinants of the dynamics of terrestrial ecosystems. There is a long tradition in the study of these interactions, their mechanisms and their consequences using experimental, observational and theoretical approaches. Empirical studies overwhelmingly focus at the level of species pairs or small sets of species. Although empirical data on these interactions at the community level are scarce, such studies have gained pace in the last decade. Studying plant-plant interactions at the community level requires knowledge of which species interact with which others, so an ecological networks approach must be incorporated into the basic toolbox of plant community ecology. The concept of recruitment networks (RNs) provides an integrative framework and new insights for many topics in the field of plant community ecology. RNs synthesise the set of canopy-recruit interactions in a local plant assemblage. Canopy-recruit interactions describe which ("canopy") species allow the recruitment of other species in their vicinity and how. Here we critically review basic concepts of ecological network theory as they apply to RNs. We use RecruitNet, a recently published worldwide data set of canopy-recruit interactions, to describe RN patterns emerging at the interaction, species, and community levels, and relate them to different abiotic gradients. Our results show that RNs can be sampled with high accuracy. The studies included in RecruitNet show a very high mean network completeness (95%), indicating that undetected canopy-recruit pairs must be few and occur very infrequently. Across 351,064 canopy-recruit pairs analysed, the effect of the interaction on recruitment was neutral in an average of 69% of the interactions per community, but the remaining interactions were positive (i.e. facilitative) five times more often than negative (i.e. competitive), and positive interactions had twice the strength of negative ones. Moreover, the frequency and strength of facilitation increases along a climatic aridity gradient worldwide, so the demography of plant communities is increasingly strongly dependent on facilitation as aridity increases. At network level, species can be ascribed to four functional types depending on their position in the network: core, satellite, strict transients and disturbance-dependent transients. This functional structure can allow a rough estimation of which species are more likely to persist. In RecruitNet communities, this functional structure most often departs from random null model expectation and could allow on average the persistence of 77% of the species in a local community. The functional structure of RNs also varies along the aridity gradient, but differently in shrubland than in forest communities. This variation suggests an increase in the probability of species persistence with aridity in forests, while such probability remains roughly constant along the gradient in shrublands. The different functional structure of RNs between forests and shrublands could contribute to explaining their co-occurrence as alternative stable states of the vegetation under the same climatic conditions. This review is not exhaustive of all the topics that can be addressed using the framework of RNs, but instead aims to present some of the interesting insights that it can bring to the field of plant community ecology.
Les visions et référentiels des politiques de développement territorial dans l’arganeraie : retour sur 10 ans d’initiatives et de projets
(Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, 2019) Jean-Paul Dubeuf; Saïd Boujrouf; Bruno Romagny; Mohamed Alifriqui
Les zones d’arrière-pays des pays du pourtour méditerranéen auxquelles appartient l’arganeraie ont donné lieu à de nouvelles formes d’interventions publiques généralement basées sur la valorisation des produits de terroir et des ressources patrimoniales, Dans le cadre d’un projet de recherches partenarial, les dispositifs de soutien en faveur de l’arganeraie notamment via le Pillier II du Plan Maroc Vert sont étudiés. L’analyse de documents programmatiques, d’observations participantes, et d’entretiens avec les différentes catégories d’acteurs permet d’éclairer les objectifs de ces politiques et les visions du monde qu’elles portent. Par une approche cognitive des politiques publiques, leurs connexions avec les réalités et les attentes des sociétés locales sont discutées en termes de mise en œuvre. Il ressort que les objectifs de compétitivité restent leur paradigme dominant par lequel prévalent les logiques de compétitivité et les exigences de professionnalisation et de spécialisation de manière mimétique par rapport au modèle dominant en Europe. Par exemple, l’appropriation des signes de qualité, décidée de manière descendance semble peu effective et ne pas correspondre aux besoins des marchés locaux. Ce faisant, en ne prenant pas en compte la complexité des systèmes de production locaux de l’arganeraie, espace multiséculaire de pluri-activité, ils ignorent souvent les enjeux de survie à court terme auxquels sont confrontés de nombreux acteurs locaux. Les dispositifs participatifs restent formels, et pour remédier à cette déconnexion, un renforcement plus appuyé des capacités humaines et la formation pourrait générer de nouvelles aptitudes organisationnelles, permettre de dépasser les effets d’opportunisme et favoriser l’émergence de projets issus des acteurs locaux, donc mieux articulés avec leurs attentes.
<scp>RecruitNet</scp>: A global database of plant recruitment networks
(Wiley, 2022) Miguel Verdú; José Luis Hernando Garrido; Julio M. Alcántara; Alicia Montesinos‐Navarro; Salomón Aguilar; Marcelo A. Aizen; Ali A. Al‐Namazi; Mohamed Alifriqui; David Allen; Kristina J. Anderson‐Teixeira
Plant recruitment interactions (i.e., what recruits under what) shape the composition, diversity, and structure of plant communities. Despite the huge body of knowledge on the mechanisms underlying recruitment interactions among species, we still know little about the structure of the recruitment networks emerging in ecological communities. Modeling and analyzing the community-level structure of plant recruitment interactions as a complex network can provide relevant information on ecological and evolutionary processes acting both at the species and ecosystem levels. We report a data set containing 143 plant recruitment networks in 23 countries across five continents, including temperate and tropical ecosystems. Each network identifies the species under which another species recruits. All networks report the number of recruits (i.e., individuals) per species. The data set includes >850,000 recruiting individuals involved in 118,411 paired interactions among 3318 vascular plant species across the globe. The cover of canopy species and open ground is also provided. Three sampling protocols were used: (1) The Recruitment Network (RN) protocol (106 networks) focuses on interactions among established plants ("canopy species") and plants in their early stages of recruitment ("recruit species"). A series of plots was delimited within a locality, and all the individuals recruiting and their canopy species were identified; (2) The paired Canopy-Open (pCO) protocol (26 networks) consists in locating a potential canopy plant and identifying recruiting individuals under the canopy and in a nearby open space of the same area; (3) The Georeferenced plot (GP) protocol (11 networks) consists in using information from georeferenced individual plants in large plots to infer canopy-recruit interactions. Some networks incorporate data for both herbs and woody species, whereas others focus exclusively on woody species. The location of each study site, geographical coordinates, country, locality, responsible author, sampling dates, sampling method, and life habits of both canopy and recruit species are provided. This database will allow researchers to test ecological, biogeographical, and evolutionary hypotheses related to plant recruitment interactions. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications.