No abstract

Le massif d'Ouanougha abrite une végétation forestière à plus de m d'altitude. Le cortège floristique de cette forêt à Cedrus atlantica et Quercus rotundifolia est très riche et comporte beaucoup d'espèces présentant un intérêt économique indéniable. La préservation et la valorisation de ce patrimoine naturel nécessitent un inventaire de la flore existante et des enquêtes ethnobotaniques. Mots clés : Plantes médicinales -Enquête ethnobotaniquePréservation et valorisation -Ouanougha (M'Sila, Algérie) Plants of medicinal and ecological interest in the Ouanougha's region (M'Sila, Algeria)Abstract: The Ouanougha's massif houses a forest vegetation beyond , m of altitude. The floristic procession, of this forest of Cedrus atlantica and Quercus rotundifolia, is very rich and includes many species of undeniable economic interest. The preservation and enhancement of this natural heritage requires an inventory of the existing flora and ethnobotanic surveys.

Environmental forcing affects biodiversity in some parts of the biosphere where many sensitive species, including endemic and rare species, respond through changes in their geographical distribution. Modelling of spatial dynamics of species is crucial to advance our understanding of species' adaptive behaviour and sensitivity to environmental changes and forcings. The present study aimed at assessing suitable habitats of the Atlas cedar (Cedrus atlantica) in North Algeria for the current period (1990-2000) and predicting its future range in 2050 and 2070, following climate warming scenarios. The Maximum Entropy (Max-Ent) model was used to model the present and future potential distribution of Atlas cedar forests. A total of 1328 occurrence records obtained from field surveys and 50 environmental variables were used. These variables included 19 climatic variables (WorldClim database), 21 edaphic proprieties (SoilGrids database), and 10 topographic traits (retrieved from a 30 m digital elevation model). MaxEnt showed high predictive power with a significant value of Area Under Curve (AUC=0.988). Potential distribution of Cedrus atlantica forests for the present period was confined to mountain areas (predicted potential range size = 2089 km²). Environmental factors with the highest percentage of contribution included: soil total nitrogen (22.2%), elevation (20.5%), mean temperature of the most humid quarter 'Bio8' (18.8%), slope (12.9%), soil total carbon (10.3%), and precipitation of the driest month 'Bio14' (3.4%). The species range is expected to reduce significantly under future climate change scenarios (decline of about 70.4-80.6% of its current potential distribution), with a shift towards more humid conditions, in this case to the north and east towards more humid climates and mesic habitats. The predicted shifts in the altitude gradient follow in the direction of higher elevations, with the disappearance of cedar forests at low altitudes. This indicates that the identified Atlas cedar refugia resulting from climate change are determined by humidity. Our findings provide information on the magnitude of environmental forcings that seriously threaten Cedrus atlantica forests in drought-prone areas in North Africa. It is therefore necessary to implement effective strategies to preserve and protect more sensitive forests.

Seed germination is generally the critical step in seed establishment and thus the determination of successful crop production. This study was focused at examination of the biochemical and germination parameters effected by low water potential which was generated by polyethylene glycol (PEG) 6000 and mannitol, related to drought stress and growth of Waha durum wheat genotype. Two tests were carried out in a growth chamber; the first comprises seed germination into Petri dishes in the presence of different concentrations of the two osmoticums (0, 5, 10, 15 and 20 % of PEG6000 and mannitol). The second test was carried out in nutrient solution BD medium. Our results shows that Both PEG -6000 and mannitol reduced germination. Therefore, a rapid increase was observed in the rate of germination both for the control plants and the plants subjected to a concentration of 5 g/L and 10 g/L and changes in proportion to the time. For the concentration of 15 g/L and 20 g/L, this phase is very short, which explains the reduced germination rate due to the inhibitory effect of the two osmoticums on germination. In this study, PEG-6000 treatments resulted in an increase of some proteins and a decrease of others. Waha displayed 12 bands for control plants, 40 bands for PEG-6000 stressed plants (all treatments) and 35 bands for mannitol treatments.

No abstract