Contribution of the Geosystemic Method to Studies 0n the Dynamics of Middle Atlas Forest Landscapes: the Case of the Forest and Pre-forest Environment of Jbel Tichoukt (Central Middle Atlas, Morocco) AZAMI HASSANI ADIL, PhD researcher in Biogeography –USMBA- FES- Morocco Abstract: This article focuses on the scientific contribution of the geosystemic approach to the study of environmental and vegetation dynamics in the Moroccan Middle Atlas, through the study of a typical model of the Middle Atlas landscape (forest and pre-forest massif of Jbel Tichoukt in the central Middle Atlas). The application of this fine geographical method allowed the restructuring of this nested mountainous landscape, according to ecological and phytogeographical criteria, as well as the degree of human impact. Its results also allowed the analysis of the complex relationships between its different biotic, abiotic and anthropic constituents and the identification of the different dynamic trends of the vegetation within the two identified ecological sectors (northern and southern), divided into 7 geocomplexes and 56 geofacies. Keywords: Geosystemic method- Ecological Sector- Geocomplex- Geofacies- Central Middle Atlas- Jbel Tichoukt Contribution de la méthode géosystémique aux études sur la dynamique des paysages forestiers moyen-atlasique : cas du milieu forestier et pré-forestier de JbelTichoukt (Moyen Atlas central, Maroc) Résumé Cet article met l’accent sur la contribution scientifique de l’approche géosystémique à l’étude de la dynamique du milieu et de la végétation dans le Moyen Atlas marocain, et ce à travers l’étude d’un modèle typique du paysage moyen-atlasique (massif forestier et pré- forestier de JbelTichoukt dans le Moyen Atlas central). L’application de cette méthode géographique fine a permis la restructuration de ce paysage montagneux emboité, en fonction des critères écologiques, phytogéographiques, aussi bien que le degré de l’impact humain. Ses résultats ont permis, également d’analyser les relations complexes entre ses différents constituants biotiques, abiotiques et anthropiques et de cerner les différentes tendances dynamiques de la végétation au sein des deux secteurs écologiques (septentrional et méridional) identifiés, scindés en 7 géocomplexes et 56 géofaciès. Mots clés : Méthode géosystémique- Secteur écologique- Géocomplexe- Géofaciès -Moyen Atlas central- Jbel Tichoukt Introduction 135 The forest environments of the Middle Atlas region are well known and their vegetation is of great interest according to the methods applied since the 1930s. These approaches applied to date are interesting and multiple (Emberger, 1934, 1939; Emberger and Maire, 1934; Boudy, 1950; Pujos, 1964, 1966; Lepoutre, 1963, 1964; Lecompte and Lepoutre, 1975; Lecompte, 1969, 1986; Peyre, 1975, 1979; Quezel and Barbéro, 1986; Barbéro & al, 1981; Fennane, 1982, 1988; Benabid, 1982, 1988, 1994; Quarro, 1985; Labhar, 1998; Nabil, 2006). The choice between these methods to study the internal dynamics of the complex geographical landscape requires the adoption of an adequate, relevant and integrated approach that brings new ideas to the study of forest environments, and that allows to go beyond the dehumanised, technical and sectorial approaches of the landscape. 1. Research on Middle Atlas Vegetation: Biophysical Relationships Are the Most Dominant 1.1 Contribution of the Phytoecological Approach: a Method Widely Applied In the Middle Atlas Research on the Middle Atlas vegetation has been of great importance from a phytoecological approach. This method, which has been widely applied in this region, aims to define plant groupings and vegetation series in relation to an ecological factor or, alternatively, in relation to environmental factors. It is a method based on floristic surveys that introduce the ecological and structural parameters of the environment. Indeed, in-depth scientific research began in the 1950s in the light of Emberger's earlier work (1930). His work on Moroccan vegetation in relation to climate resulted in a division of bioclimatic stages in Morocco and the establishment of a phytogeographic map of Morocco at a scale of 1/1.500.000. He was able to base his own concept of the Mediterranean climate and the distribution of Mediterranean vegetation on his synthetic expression of the rainfall quotient (Q). These earlier works of Emberger formed the theoretical basis and opened a new perspective for phytoecological research thereafter (Emberger, 1934, 1939; Emberger and Maire, 1934). During the 1960s, phytoecological work has multiplied, focusing on the Moroccan cedar forest and more particularly the Middle Atlas cedar forest, which was the subject of a large number of studies. The work on the constraints and conditions of its regeneration was the focus of this silvicultural phase (Pujos, 1964, 1966; Lepoutre, 1963, 1964; Lecompte and Lepoutre, 1975; Ezzahiri, 1989). Other forest species also benefited from the work carried out later on Moroccan vegetation, including that of the Middle Atlas, notably 136 Quercus rotundifolia, Quercus canariensis, Juniperus thurifera, Tetraclinis articulata and Pinus pinaster. At the same time, in-depth bioclimatic research on the central and eastern Middle Atlas was carried out and opened up to a new direction of analysis constituting the basis of what Lecompte called "dynamic phytoclimatalogy", emphasising the relationship between the distribution and horizontal structuring of the vegetation and the climatic factor, by introducing the notion of the climatic gradient (Lecompte, 1969, 1981, 1986; Peyre, 1975, 1979). 1.2. The Phytosociological Method: a Dehumanised Approach with Limited Research in the Middle Atlas Phytosociological research did not follow the same trend as the phytoecological approach, and extended studies only really began in the early 1980s. Phytosociological surveys were certainly carried out before that date, but always as a simple corollary of local, or even one-off, phytoecological work, or work devoted to a particular species (Benabid, 2000). The first studies were carried out on forest and pre-forest ecosystems (Barbéro et al., 1981; Benabid, 1982, 1994; Fennane, 1982, 1988; Quezel and Barbéro, 1986). Subsequently, they turned to the study of pre-steppe structures and matorrals (Achhal, 1986; Berbéro et al, 1982; Benabid, 1988; Quezel et al, 1992). However, these studies remain limited and disparate in the Middle Atlas and are generally integrated into the framework of collective tours in Morocco with the purpose of better understanding Mediterranean forest ecosystems (Labhar, 1998). The phytosociological approach can be defined as the science of plant groupings, ordered in a hierarchical system where the association is the elementary unit (Géhu and Rivaz Martinez, 1981 in Meddour, 2011). The system includes units of progressively higher hierarchical rank (alliances, orders, classes and divisions). The methodological basis of phytosociology is the vegetation survey. It is a method that makes less use of species-factor relationships and can therefore be practised with a minimum of information on the biotope (altitude, exposure, slope and nature of substrate may suffice). (Benabid, 1994). This approach has been introduced progressively since the first decades of the 20th century by numerous researchers belonging to different schools (classical or sigmatist phytosociology, serial phytosociology and dynamico- catenal phytosociology). 137 The school most adopted by researchers who have carried out studies on the forest and pre-Forest structures of the Middle Atlas (Benabid, 1988; Fennane, 1982, 1987) is that developed under the impetus of Braun-Blanquet in the 1930s. The latter had the merit of uniting the methods of analysis, naming and classifying groupings into a coherent body of doctrine known as Zuricho- Montpellieran or sigmatist phytosociology, modified and refined by Tuxen in the 1950s. In general, this Braun-Blanqueto-Tuxenian (classical) method presents a theoretically universal method for describing and understanding vegetation facts, from both a phytoecological and phytogeographical perspective (Gillet & al, 1991 in Meddour, 2011). However, its results are too abstract for a geographer and insufficient for the description of human impact on vegetation cover. (Deil, 1992 in Labhar, 1998). 2. The Geosystemic Method: a Detailed Analysis of the Geographical Complex, Useful for Studying the Dynamics of the Environment and the Middle Atlas Vegetation Another approach to the study of vegetation and the Middle Atlas environment was followed and introduced through the work of two geographers, Labhar, (1985, 1998) and Nabil, (1985, 2006). Thanks to these two Moroccan researchers, the geosystemic approach has been echoed by their followers (Makrane, 2016 & Azami Hassani, 2020), contributing to the widening of the application space of this method in the different areas of the Moroccan Middle Atlas. In 1968, Bertrand presented the main features of his geosystemic method, starting from his own definition of landscape. Landscape is a central concept and a real object of global physical geography: "Landscape is not the simple addition of disparate geographical elements. It is, on a portion of space, the result of the dynamic and therefore unstable combination of physical, biological and anthropic elements which, by reacting dialectically on each other, make the landscape a unique and indissociable whole in perpetual evolution". According to this definition, Bertrand drew the theoretical