Diversité floristique d´un lac du Bas-Sahara Algérien

Nous avons examiné la composition et la dynamique de la végétation vasculaire spontanée dans le Lac Ayata (Vallée d’Oued Righ, Bas-Sahara algérien). Le site se situe entre 33°29’17’’N à 33°29’48’’N et 05°59’10’’E à 05°59’37’’E. L’échantillonnage systématique de la flore a révélé l’existence de 13 espèces appartenant à 8 familles et 13 genres. Le plan d’eau est dépourvu de plantes submergées. Les types biologiques, la structure et la physionomie de la végétation sont été déterminés. L’occupation du sol par la végétation est cartographiée afin d’illustrer les répartitions saisonnières des espèces végétales dominantes. Des géostatistiques sur les surfaces occupées par la végétation ainsi que sur sa dynamique saisonnière sont ensuite obtenues puis discutées. Les types biologiques les plus fréquents sont les chamaephytes (53,8%) et les thérophytes (23,1%), qui caractérisent la végétation désertique ayant un recouvrement faible et une hauteur basse. Par ailleurs, la cartographie de la végétation a révélé l’existence de 3 types de formations végétales: (i) une végétation halophytique représentée par des espèces Chénopodiacées qui sont réparties tout autour des abords du plan d’eau; (ii) une végétation hydrophytique représentée par Phragmites communis et Juncus maritimus ; et (iii) une végétation éparse représentée par Limoniastrum guyonianum et Triganum nudatum. Le lac Ayata abrite une flore peu diversifiée mais bien adaptée aux conditions écologiques défavorables qui règnent sur le sol (salinité) et le climat (sécheresse)

Short-term land degradation driven by livestock grazing does not affect soil properties in semiarid steppe rangelands

The soil–vegetation relationships are reciprocal and fundamental for terrestrial ecosystem integrity. However, the long-term degradation of vegetation cover alters edaphic conditions, which can lead to degradation of habitats, and obstructs proper ecosystem functioning. This study aimed to assess the effects of the degradation of perennial steppe vegetation due to overgrazing (i.e., continuous and free grazing) on the physicochemical characteristics and soil fertility in the steppe rangelands of Halfa (Macrochloa tenacissima syn. Stipa tenacissima) of semi-arid areas in Algeria. The edaphic parameters of the superficial horizons of degraded steppes and other undegraded steppes were compared in order to suggest adequate strategies for rangeland management and remedy the degradation of vegetation and thereby ensure the sustainability of these agro-pastoral systems. The soil, collected from the surface horizons (A1 and A2) of pedological profiles, was analyzed according to standard methods of soil physicochemical analyses to determine the particle size fractions (clay, silt, and sands), pH, electrical conductivity (EC), total and active CaCO3, organic matter (SOM), organic carbon, total nitrogen, and the C:N ratio. The distribution and variation of soil parameters between horizons and the two types of steppes were examined using generalized linear mixed models and redundancy analysis. Findings of this study revealed that the degradation of steppe vegetation cover by short-term overgrazing did not cause a significant variability in soil physicochemical parameters between degraded and undegraded steppes and the horizons A1 and A2. The sites studied have clayey–silty textures in non-degraded steppes and coarse textures dominated by sands in degraded steppes. The edaphic environment of the Halfa grass steppes was characterized by a calcareous substratum with high carbonate content (total CaCO3 = 36.8–41%, active CaCO3 = 17.5–18.5%), with an alkaline pH (8.09–8.19) and EC averaging 0.99 ± 1.24 dS/m. Soils had low SOM contents (1.42–2.93%), organic carbon (0.82–1.64%), and nitrogen (0.1–0.15%). The strong positive correlations recorded between the fine-size fractions, SOM, total CaCO3, nitrogen, and EC indicated good soil structural stability in undegraded steppes, while the negative correlations between these same variables with sand and pH substantiate the structural degradation of the soil. The negative correlation between C:N ratio and SOM indicated that the rate of SOM mineralization was rapid in semiarid steppes, with a higher fertility state in the undegraded steppe. Our findings suggest and urge to implement a restoration plan against the degradation of semi-arid Halfa steppes in order to avoid the irreversible state of soil and habitat destruction in the future because even the degradation of rangeland plant cover due to livestock overgrazing—in the short term—has not affected the edaphic characteristics of steppe rangelands

Using self-organizing maps to investigate environmental factors regulating colony size and breeding success of the White Stork (Ciconia ciconia)

We studied variations in the size of breeding colonies and in breeding performance of White Storks Ciconia ciconia in 2006–2008 in north-east Algeria. Each colony site was characterized using 12 environmental variables describing the physical environment, land-cover categories, and human activities, and by three demographic parameters: the number of breeding pairs, the number of pairs with chicks, and the number of fledged chicks per pair. Generalized linear mixed models and the self-organizing map algorithm (SOM, neural network) were used to investigate effects of biotic, abiotic, and anthropogenic factors on demographic parameters and on their relationships. Numbers of breeding pairs and of pairs with chicks were affected by the same environmental factors, mainly anthropogenic, which differed from those affecting the number of fledged chicks per pair. Numbers of fledged chicks per pair was not affected by colony size or by the number of nests with chicks. The categorization of the environmental variables into natural and anthropogenic, in connection with demographic parameters, was relevant to detect factors explaining variation in colony size and breeding parameters. The SOM proved a relevant tool to help determine actual dynamics in White Stork colonies, and thus to support effective conservation decisions at a regional scale

Diversité floristique d’un lac du bas-sahara algérien. Flora diversity of a lake at algerian low-sahara

Français.  Nous avons examiné la composition et la dynamique de la végétation vasculaire spontanée dans le Lac Ayata (Vallée d’Oued Righ, Bas-Sahara algérien). Le site se situe entre 33°29’17’’N à 33°29’48’’N et 05°59’10’’E à 05°59’37’’E. L’échantillonnage systématique de la flore a révélé l’existence de 13 espèces appartenant à 8 familles et 13 genres. Le plan d’eau est dépourvu de plantes submergées. Les types biologiques, la structure et la physionomie de la végétation sont été déterminés. L’occupation du sol par la végétation est cartographiée afin d’illustrer les répartitions saisonnières des espèces végétales dominantes. Des géostatistiques sur les surfaces occupées par la végétation ainsi que sur sa dynamique saisonnière sont ensuite obtenues puis discutées. Les types biologiques les plus fréquents sont les chamaephytes (53,8%) et les thérophytes (23,1%), qui caractérisent la végétation désertique ayant un recouvrement faible et une hauteur basse. Par ailleurs, la cartographie de la végétation a révélé l’existence de 3 types de formations végétales: (i) une végétation halophytique représentée par des espèces Chénopodiacées qui sont réparties tout autour des abords du plan d’eau; (ii) une végétation hydrophytique représentée par Phragmites communis et Juncus maritimus ; et (iii) une végétation éparse représentée par Limoniastrum guyonianum et Triganum nudatum. Le lac Ayata abrite une flore peu diversifiée mais bien adaptée aux conditions écologiques défavorables qui règnent sur le sol (salinité) et le climat (sécheresse).English. We examined the composition and dynamics of spontaneous vascular vegetation in Lake Ayata (Valley of Oued Righ Algerian, Low-Sahara). The site is located between 33°29’17’’N to 33°29’48’’N and 05°59’10’’E to 05°59’37’’E. A systematic sampling of the flora has revealed 13 species belonging to 8 families and 13 genera. The waterbody is free of submerged plants. The plant life forms, structure and physiognomy of vegetation were determined. In addition, vegetation-land-cover was mapped to illustrate seasonal distribution of dominant plant species. Geostatistics on areas covered by vegetation and its seasonal dynamics were obtained and then discussed. The most common plant life forms were chamaephytes (53.8%) and therophytes (23.1%), which characterize desert vegetation that has low recovery and low height. Furthermore, vegetation mapping revealed the existence of 3 types of vegetation: (i) halophytic vegetation represented mainly by Chenopodiaceae species, which were extended all around the edges of the waterbody; (ii) hydrophytic vegetation represented mainly by Phragmites communis and Juncus maritimus, and (iii) sparse vegetation represented by Limoniastrum guyonianum and Triganum nudatum. Lake Ayata’s flora is poorly diversified but well adapted to adverse environmental conditions prevailing on the ground (salinity) and climate (drought).

Table S5. Rarefied and extrapolated statistics of estimated species richness and diversity.

<p>Full diversity statistics of prey species richness estimators and prey species diversity indices computed using EstimateS (Colwell, 2013) for the entire study area (the overall diet), climates and landscapes of White Stork colonies in Northeast Algeria. Prey species estimates and diversity of rarefaction are represented in cells with green background, whereas extrapolation statistics are given in orange cells.</p

Table S4. Raw input dataset of White Stork diet across rural-to-urban landscapes in North African breeding grounds

<p>Model of raw data used in EstimateS 9.1.0 (Colwell, 2013) for the analysis of shared prey species estimators and similarity indices between three rural-to-urban landscapes of White Stork colonies studied in Northeast Algeria.</p

Trace metal concentrations in surface water and upper sediment of Seybouse watershed (Algeria)

<p>Spatiotemporal monitoring of surface water and sediment in Wadis of Seybouse watershed (Algeria) revealed a widespread metal contamination resulted from long-term pollution of water.</p

Comparative effectiveness of exogenous organic amendments on soil fertility, growth, photosynthesis and heavy metal accumulation in cereal crops

With soil fertility loss reached a critical state in arid and semi-arid regions, farmers are constrained to use mineral fertilizers, which are costly, non-eco-friendly and less effective in improving soil fertility than organic fertilizers such as dewatered sewage sludge (SS) and poultry manure (PM). In this regard, the current study aimed to highlight through experiments the positive effect of SS and PM applications on soil fertility and durum wheat growth. It targeted to demonstrate the safe and wise use of organic fertilization while assessing heavy metals in both soil and plant. The experiment was carried out in two batches of thirty-two pots, one for each treatment (SS and PM), in addition to the control with no fertilization. SS and PM were applied separately in three doses (D1 = 50 g, D2 = 100 g, and D3 = 200 g DM fertilizer/pot). The applications of both SS and PM induced a significant increase in plant-available phosphorus, organic matter, nitrates, moisture and electrical conductivity in soil, where these improvements were higher in PM compared to SS treatment. A significant accumulation of proline associated with an increase in biomass that were both proportional with fertilizer dose levels. Our findings revealed a loss in relative water content and leaf area of the plant. Correlations showed several significant relationships between soil parameters studied. The dose D2 of each fertilizer was the most efficient to improving both soil properties and plant components. Plant zinc concentration increased significantly with increase in soil zinc in PM amendments, however it decreased in SS. These relationships were not significant in copper for the two fertilizers. Both SS and PM improved soil fertility and plant growth compared to the control, thus this practice is a promising solution to tackle soil fertility loss and low production in drylands

Table S2. Dataset of White Stork diet from Algerian breeding colonies

<p>Raw dataset of diet composition per regurgitated pellet of the White Stork in the region of Batna (Northeast Algeria) following a criss-crossed gradient of climate and urbanization. This dataset was imported into EstimateS (Colwell, 2013) as Multiple-Sample-Based-Data</p

Raw dataset for the upcoming article of Boudjabi et al. 2017

The title of the article is: "Sewage sludge fertilization alleviates drought stress and improves physiological adaptation and yield performances in Durum Wheat (<i>Triticum durum</i>): a double edged sword