Assessment of the effects of the control of grazing system in grazed arid steppic rangelands in Algeria

Face à la dégradation dont souffre la steppe en Algérie, la mise en repos, introduite récemment, représente un moyen efficace de contrôle et de gestion des écosystèmes pâturés des parcours steppiques arides de cette région. Trois sites ont été étudiés en vue d’évaluer dans chacun d’eux les effets de l’exclusion du pâturage suivie d’une gestion en pâturage contrôlé par rapport à un usage libre. La composition et la diversité floristique de la végétation, l’état de surface du sol et la qualité fourragère des espaces contrôlés, montrent une amélioration par rapport aux terrains pâturés librement. La nécessité d’un tel aménagement dans les parcours steppiques arides ainsi que la méthode d’échantillonnage dans ce genre d’évaluation sont discutéesFacing the degradation that the steppe in Algeria suffered, the grazing system using deferred grazing, introduced recently, is an effective means to control and manage the grazed ecosystems of steppic rangelands. Three sites have been studied to assess in each of them, the effects of the managed grazing on ecosystem in comparison to the free grazed ones. The composition and plant species diversity, surface soil conditions and forage quality in controlled areas, showed improvement compared with the freely grazed land. In the present work and usually regarding similar assessment tasks, conditions and sampling design are dictated by a request made much later after the grazing management set-up. The need of such a management in the arid rangelands and the sampling method are discusse

A formal classification of the Lygeum spartum vegetation of the Mediterranean Region

Aims We examined local and regional contribution on the grasslands dominated by Lygeum spartum from Southern Europe and North Africa to produce a formalised classification of this vegetation and to identify main factors driving its plant species composition. Location Mediterranean Basin and Iberian Peninsula. Methods We used a dataset of 728 relevés, which were resampled to reduce unbalanced sampling effort, resulting in a dataset of 568 relevés and 846 taxa. We classified the plots by TWINSPAN, interpreted the resulting pools, and used them to develop formal definitions of phytosociological alliances characterised by L. spartum vegetation. The definitions were included in an expert system to assist automatic vegetation classification. We related the alliances to climatic factors and described their biogeographical features and ecological preferences. The floristic relationships between these alliances were analysed and visualised using distance‐based redundancy analysis. Results We defined eleven alliances of L. spartum vegetation, including the newly described Launaeo laniferae‐Lygeion sparti from SW Morocco and the Noaeo mucronatae‐Lygeion sparti from the Algerian highlands and NE Morocco. Biogeographical, climatic, and edaphic factors were revealed as putatively driving the differentiation between the alliances. The vegetation of clayey slopes and inland salt basins displayed higher variability in comparison with those of coastal salt marshes. Main conclusions The most comprehensive formal classification, accompanied by an expert system, of the L. spartum vegetation was formulated. The expert system, containing the formal definitions of the phytosociological alliances, will assist in identification of syntaxonomic position of new datasets

Production des Ecosystemes Steppiques a Armoise Blanche (Algerie): Variations Inter-Annuelles et Implications Pastorales

Les formations a armoise blanche (Artemisia herba-alba Asso ), couvrant environ deux a trois millions d\u27hectares, constituent les parcours les plus etendus et Jes plus homogme­nes des hautes plaines steppiques et de !\u27Atlas Saharien alge­riens. Cette steppe est actuellement marquee, au niveau des Hautes Plaines par une degradation intense sous !\u27action d\u27un piiturage d\u27autant plus efficient qu\u27une tendance a la secheresse se fait sentir depuis une dizaine d\u27annees. Le present article presente Jes principales caracteristiques du fonctionnement de cet ecosysteme au niveau de la production primaire utilisable par les ovins. Les observations portent surl\u27evolution de la phytomasse et de la composition floristique sur une periode de onze annees (1976-1986). L\u27objectif du tra­vail est d\u27apprehender Jes variations inter-annuelles de la pro­duction en relation avec la pluie, principal facteur de produc­tion

Nutritional status and dietary behaviours of Northern Algeria university students

Abstract The present study tries to assess the nutritional status and dietary behaviours in a group of undergraduate students in order to characterize their food habits and assess the quality of their diet. A cross-sectional study was conducted with 220 undergraduate university students (110 male and 110 female) aged between 19 and 24 years from the Food Department of Saad Dahlab Blida 1 University (Algeria). The data collection and nutritional evaluation were carried out using DIAL nutritional software. Male participants had significantly (P &lt; 0.005) higher body mass index (BMI) when compared to females. Significantly higher percentages of female students (P &lt; 0.005) had tried a low-fat diet (P = 0.0075) and a low-carbohydrate diet (P &lt; 0.005). The prevalence of overweight was higher among males compared to females. In contrast, a greater percentage of underweight students were observed in the group of female subjects. Related to micronutrient intake, a significant difference by sex was observed for vitamin A, C, folic acid, iron, calcium, and sodium intakes. However, females consumed more food containing vitamins C and A, whereas males’ intake of calcium, sodium, folic acid, and iron was higher than the corresponding values observed in females. To conclude, these students reported a diet characterized by a high variety of cereal products and a moderate amount of vegetables, milk and dairy products, meat, fish and eggs, dietary fats and beverages, whereas the consumption of fruits was highly infrequent.</jats:p

EVALUATION DES EFFETS DU CONTROLE DE PATURAGE DANS DES PARCOURS STEPPIQUES ARIDES EN ALGERIE

National audienceAssessment of the effects of the control of grazing system in grazed arid steppic rangelands in Algeria. Facing the degradation that the steppe in Algeria suffered, the grazing system using deferred grazing, introduced recently, is an effective means to control and manage the grazed ecosystems of steppic rangelands. Three sites have been studied to assess in each of them, the effects of the managed grazing on ecosystem in comparison to the free grazed ones. The composition and plant species diversity, surface soil conditions and forage quality in controlled areas, showed improvement compared with the freely grazed land. In the present work and usually regarding similar assessment tasks, conditions and sampling design are dictated by a request made much later after the grazing management set-up. The need of such a management in the arid rangelands and the sampling method are discussed

Species pools along contemporary environmental gradients represent different levels of diversification

Aim - Within a region, different habitat types are characterized by different species and some habitat types have higher species diversities than others. Different habitat types are also characterized by different phylogenetic clades. However, it is not known whether – within a given region – some habitat types have species pools that are more phylogenetically diversified than others. We investigated whether species pools in contemporary habitat types represent different levels of diversification of angiosperms and, if so, whether these differences correlate with particular environmental factors. We tested these relationships in a region of recent geological origin possessing a comparatively young flora, and compared the result with standard analyses of species diversity. Location The Netherlands. Methods - We studied angiosperms across the full range of habitat types present in the Netherlands. We characterized levels of diversification represented in species pools within each of these habitat types with respect to (1) taxonomic diversification, i.e. the rate of increase of richness across taxonomic ranks (relative to a null expectation for a given species richness), and (2) cladogenic diversification, i.e. the average cladogenic distance of species from the root of a phylogenetic tree of the species pool within a given region. Results - Species pools of different habitat types represented different levels of taxonomic and cladogenic diversification. These differences were strongly correlated with the environmental characteristics of the habitat type. Greater levels of taxonomic diversification were represented in the species pools of relatively dry and open habitat types. Greater levels of cladogenic diversification were represented in habitats with both dry and weakly acidic soils. The relationship between environmental factors and taxonomic and cladogenic diversification (r2 = 0.88 and 0.76, respectively) was stronger than that between environmental factors and species richness (r2 = 0.34). Main conclusions - Within a region, species resulting from particularly high rates of diversification accumulated in particular habitat types. These habitat types represent specific contemporary abiotic environments and have a tighter relationship with levels of diversification than with species richness