Contribution of the Geosystemic Method to Studies 0n the Dynamics of Forest Landscapes: the Case of the Forest and Pre-forest Environment of Jbel Tichoukt (Central Middle Atlas, )

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

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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 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 also benefited from the work carried out later on Moroccan vegetation, including that of the Middle Atlas, notably

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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).

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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 outline of his geosystemic method of landscape by insisting on the dynamic character between the physical and social laws of the landscape, it is a three-dimensional combination (physical, biological and human) and as a dynamic entity (Clément, 1994).

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This approach aims to study vegetation in the geosystem and analyse the dynamic interrelationships between the biophysical environment and the human activities associated with a territory. The concept of geosystem (geocomplex in Bertrand's sense) was introduced and developed towards the end of the 1960s by the pioneer of this method G. Bertrand, inspired by the work of Soviet geography (Sochava, 1960) and based on the systemic method applied to the study of the natural environment. For him, the geosystem emphasises the geographical complex and the overall dynamics. The geosystem is a concept used in some anthropological and ethnobotanical studies and is open to other dimensions of the interface: cultural, social and economic (Bertrand, 1989 in Barrué-pastor and Muxart, 1992). To this end, the geosystem relates the landscape by revealing the interaction between nature and society in a spatial and temporal dimension. Thus, it constitutes an effective concept for the geographer to dismantle this landscape and to identify the relationships of its different elements (biotic, abiotic and anthropic) without being locked into causal relationships (Clary, 1987). Figure 1: Theoretical definition of a geosystem (Bertrand, 1968)

Ecological Biological potential farming

Geosystem

Anthropic action

2.1. Contribution of the Geosystemic Method in the Study of the Current Dynamics of the Forest and Pre-forest Environment of Jbel Tichoukt (Central Middle Atlas) 2.1.1. The Forest and Pre-forest Massif of Jbel Tichoukt: Criteria Used and Classification Systems for Landscape Complexes The Jbel Tichoukt is part of the central Middle Atlas, in its folded part. It is a high anticlinal chain, which culminates at 2794 m of altitude at the Lalla Oum-

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Elbent peak and spreads out over nearly 30 kms from S.W to N.E. This composite massif constitutes the highest mountain. It connects the folded Middle Atlas chains with the plains of the Upper Moulouya towards the S/S.E, the chains of the folded Middle Atlas with the plains of the Upper Moulouya, which gives it particular and variable ecological conditions in space and time, with the vertical and horizontal conjunction of several types of forest, pre-forest, pre- steppe and steppe ecosystems. Figure 2: Site and Geographical Location of Jbel Tichoukt

Source: Azami Hassani Adil, 2020- based on the digital terrain model and assembly of topographic funds at 1/50.000 and administrative division map According to the geosystemic approach which subdivides the geographical space into homogeneous and hierarchical units, rigorous classification systems of landscape complexes have been proposed, either in Morocco or elsewhere (Galoux, 1967; Bertrand, 1974; Long, 1974; Labhar, 1998; Nabil, 1985;

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Simoune, 2000) in order to present the hierarchy and interlocking which structure each landscape studied. Among these classifications, we cite the one adopted by the geographer Labhar in (1998):

Inspired by this classification and following ecological, phytogeographical and geomorphological criteria changing at the level of the Tichoukt massif, the division is based on the following chorological units (Azami hassani, 2020): Ecological sector: Two distinct ecological sectors identified in Tichoukt, namely: - A northern sector: characterised by topo-climatic, lithological and phytoecological conditions that change from the south-west to the northeast and from the lower slopes to the ridge of the massif. - A southern sector: with different ecological and geomorphological conditions compared to the northern sector, accompanied by a remarkable anthropic presence on the ground. Geocomplexes: Seven geocomplexes identified at the scale of the massif, of which four geocomplexes in the northern ecological sector and three geocomplexes in the southern ecological sector.

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Geofacies: We obtained 56 lower homogeneous units at the scale of the massif, of which 27 geofacies belong to the geocomplexes of the northern sector and 29 geofacies to the geocomplexes of the southern sector. Table 2: Chorological Units in the Tichoukt Massif

Sectors Geocomplex Number of geofacies

G1 : High mountain geocomplex of atlantica and 5 Xerophytes on steep slopes and limestone substrate

G2 : High altitude geocomplex in high 8 forest or coppice

Northern G3 : Mid-slope matorralized geocomplex of Quercus 5 rotundifolia

G4 : Lowland pre-forestry geocomplex 9

G5 : Forest and Pre-Forest geocomplex of the western front and 12 upper central reverse

G6 : Pre-forestry geocomplex of the eastern reverse 10

Southern G7 : Steppe geocomplex of the lower slopes and on covered 7 glacis Source: AZAMI HASSANI ADIL, 2020 - Division based on the processing of plant surveys and field investigations 2.1.2. Results and discussion The geosystemic method allowed the restructuring of the studied territory according to ecological and phytogeographical criteria, as well as the degree of human impact. It also allowed the analysis of the current dynamics of the vegetation within the geocomplexes of each identified sector (Azami Hassani, 2020): For the geocomplexes of the northern sector: - The dynamics of the High mountain geocomplex of Cedrus atlantica and Xerophytes on steep slopes and Limestone substrate is controlled by the thermal and edaphic conditions that are unsuitable for the maintenance of the Cedrus atlantica, Quercus rotundifolia and Juniperus thurifera, which have no natural regeneration. The geocomplex is currently invaded by cold alticolous steppes with the almost total absence of trees from 2400 m altitude.

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- The high-altitude forest geocomplex consists of a pure Quercus rotundifolia forest, either as a high forest or as a coppice. Its current dynamics depend on the specific ecological conditions of each geofacies. With the exception of a few blocks on slopes exposed to the NW and NE where the Quercus rotundifolia constitutes a climatic stage in good bioclimatic and edaphic conditions and less altered by human action, the other geofacies are more or less disturbed and show a regressive or stable dynamic. They often lack spontaneous regeneration by stump sprouting. - The Mid-slope matorralized geocomplex of Quercus rotundifolia marks the transition from one forest geocomplex to another on the mid-slopes with a clear pre-forest character. Its dynamics are generally regressive. These unfavourable ecological conditions and the strong human influence reflected in the multiplication of degradation and xeric species. - The last geocomplex, dominated by Juniperus phoenicea and other heliophilous and xerophilous species. It is subject to the effects of the basin (Foehn effects), which imposes an accentuated aridity with a dry, hot and fairly prolonged summer season. Similarly, anthropogenic disturbances are frequent (overgrazing, woodcutting and overexploitation of Rosmarinus officinalis). The dynamics of the vegetation marked by a decline in the cover of the upper strata to the benefit of dryland shrubs, hence its evolution towards a pre-steppe stage.

For the geocomplexes of the southern sector: - The forest and pre-forest geocomplex in the west of the sector: occupies a large part of the Oum-jniba basin and extends towards the centre at the level of the large Limestone ridges of Ich-Iguidère, Ich-El Mers, Jbel Abou-Krabène and Tadmaynt Ich-Temellaline. Its bioclimate is of the upper semi-arid type with very cold winters, less abundant rainfall (averaging between 450 and 500 mm/year) and frequent snowfalls in winter. Its current dynamics are considered stable or regressive. It is mainly controlled by strong anthropic pressure and active erosive dynamics on the calcareous or sandstone-marlstone uplands, which is manifested by the recent development of open gullies, soil stripping and the concentration of scree and pebbles on the surface. Its advanced degradation is manifested by the total absence of regeneration, the opening up of old Quercus rotundifolia forests and the matorralisation of the most degraded coppices, with a proliferation of xerophytes. The exception to this is the old Quercus rotundifolia forests, where their high

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sociability and the Tensiftian sedimentary deposits favour soil fixation and the maintenance of water reserves, which contributes to the stability of certain geofacies within this geocomplex. - The geocomplex on the eastern side of the lacerated ridges and dissected plateaus of El Mers: Its vegetation is pre-forest-like, dominated by a high matorral with Juniperus phoenicea. Its location, sheltered from humid influences and at the same time subject to the action of the Foehn effects, makes this geocomplex one of the driest of the massif. Its current dynamics are regressive. This is attributed to three main factors: First is the pronounced water deficit due to the sheltering and aridity effect towards the East. The second factor is the unfavourable edaphic conditions due to the dominance of sandstone-limestone and marl- sandstone substrata, which cause the rapid drying of the soil and induce significant water erosion. Third, the strong human exploitation is manifest on the ground by the extension of ploughing voids and clearings in the middle of the matorral. - The steppe geocomplex towards the lower slopes and on covered glacis and open depressions. Its vegetation is clearly steppe based on Stipa tenacissima where it attests to the highest aridity of rainfall in the whole massif. Three factors hinder its current dynamics. The first is related to the climatic drought, which is very pronounced, due to the pronounced aridity towards the Moulouya. The second factor is linked to morphogenetic activity, particularly on the upper and mid-slopes, which are concave and clayey, causing the vegetation to dismantle and blocking its establishment on the steep marly inclined slopes; and the third is linked to permanent overgrazing in a winter range with poor flowering, which continually reduces its vegetation.

Conclusion Although the geosystemic method is not widely applied to the study of the internal dynamics of the environment and vegetation in the Middle Atlas, its scientific contribution has already been tested in the study of the Middle Atlas forest and pre-forest mountain ranges (Labhar, 1985, 1998; Nabil, 1985, 2006; Makrane, 2016 & Azami Hassani, 2020). It is the most appropriate method for this kind of research topic and very compatible with the mountainous nature of the Middle Atlas region, as it is based on a complex hierarchical classification system. It is a global and integrated geographical method, which implies a fine and large-scale study of the geographical complex of the forest landscape,

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leading to the analysis of the complex relationships between its different biotic, abiotic and anthropic constituents.

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