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Abstract

The aims of this work are to investigate the chemical composition, the antibacterial activity of the essential oil and the chromosome numbers of two populations of Hertia cheirifolia. The samples were collected in the flowering stage, in eastern Algeria locality. The aerial parts of H. cheirifolia were submitted to a hydro-distillation. GC and GC / MS analysed the chemical compositions of the obtained essential oils. The antibacterial activity of essential oils was evaluated using the disks diffusion method against ten bacterial strains. For karyotypic analysis, the squashing method is used. Fifty-eight compounds representing 98.93% of the total oil were identified in H. cheirifolia. The chemical composition is dominated by the presence of major products, α-pinene (48.49 - 53.85%) and Germacrene-D (2.64 - 12.66%). Two distinct chemical breeds were identified, the α-pinene-spathulenol of Batna population, and the α-pinene-germacrene-D of Setif population. The essential oil of H. cheirifolia has a moderate activity against bacteria tested. In contrast, the strains E. coli ATCC 25922, P. syringae ATCC 53543 and E. fecalis ATCC 49452 are resistant to H. cheirifolia essential oils. The observations of root cells meristematic at metaphase of H. cheirifolia gave a diploid chromosome number 2n = 2x = 20, with a basic chromosome number (x= 10).

Abstract

This study was aimed to determine the chemical composition of essential oils obtained from aerial parts of Thymus algeriensis Boiss. & Reut. and Marrubium vulgare L. collected in the Aures region of Algeria. Essential oils were extracted by steam distillation method and analyzed using GC-MS and GC-FID techniques. Thirty-five (35) and twenty-nine (29) components were identified respectively in T. algeriensis and M. vulgare essential oils to represent respectively 94.8% and 75.7% of the total oil composition. The main compounds of T. algeriensis oil were germacrene D (29.6%), β-caryophyllene (11.0%), E-β-farnesene (7.8%), bicyclogermacrene (4.4%) and δ-cadinene (4.0%), while, β-bisaboene (36.3%), β-caryophyllene (7.8%), phytol (6.2%), nonacosane (4.0%) and heptacosane (3.3%) were the main components of M. vulgare oil. The richness of these two oils in germacrene D and β-bisaboene respectively could suggest a new bioactivity.

Abstract

The present study attempts to analyze the essential characteristics of the global problems in the development of human society at the present stage and to highlight the place of the demographic problem as an objective factor for the existence of modern civilization. It clarifies the criteria for determining a problem as a global one and makes classification from a geographic point of view. It identifies the causes for the demographic problem, analyses and specifies its different dimensions at the global, regional and national levels.

Abstract

The forest of Chettaba is of great ecological importance for the Constantine region. It is characterized by a very heterogeneous forest cover, the dominance of forest species (Pinus halepensis and Quercus ilex) and an advanced stage of degradation. Vegetation in this region reflects the climate. The summer is dry and hot while the winter is rainy and cold. Indeed, the combination of rain and temperature directly influences the physiology of the vegetation in this forest. The main objective of this work is to characterize the different responses of Aleppo pine and holm oak seedlings and to specify the biochemical variations under the seasonal effect. Biochemical assays of proline, soluble sugars, total proteins and chlorophyll were quantified in the different organs of two species for each of the years 2018–2019. The results obtained show very significant accumulation of total soluble sugars and proline in holm oak and Aleppo pine leaves compared to stems and roots during the winter season (520 ± 20 and 370 ± 17.98 µmol/mg DM respectively). Contrary to the previous results, the highest total protein levels were recorded during the summer with levels of 0.666 ± 0.116 and 1,626 ± 0.107 mg/g FM. Parallel to the accumulation of these three solutes, a gradual decrease in the chlorophyll pigment content was recorded in winter and summer.

Abstract

The objective of this study is to evaluate the antioxidant activities of six medicinal plants growing in Algerian Aurès Mountains. Total phenolic and flavonoids contents were measured using colorimetric methods, and the antioxidant capacities were evaluated using the DPPH radical scavenging and β-carotene bleaching tests. Juniperus phoenica L. had significantly the higher total phenolic compounds (53.6±3.86 mg GAE.g−1 DM) (p<0.05); followed by Romarinus officinalis L. (26.1±3.15 mg GAE.g−1 DM) and Artemisia campestris L. (20.5±1.99 mg GAE.g−1 DM). Artemisia campestris L. had significantly the higher flavonoid contents (11.1±0.56 mg QE.g−1 DM) than other studied plants (p<0.05). The best antiradical activity was observed in Thymus algeriensis extracts (EC50=11.1±0.33 µg.ml−1) and Romarinus officinalis L. (EC50=15.3±0.9 µg.ml−1). β-carotene bleaching test showed that the herbs’ phenolic compounds Antioxidant Activity (AA%) value was found in the range of 64-84%, whereas that of the standard antioxidant ascorbic acid was 51±2.4%. The present results indicate that medicinal plants from the Algerian Aurès mountains could be explored in food and pharmaceutical industries for development of natural’s antioxidant agents.

Abstract

The aim of the present study aims to establish the impact of different restoration techniques (soil and vegetation works) of five pioneer species of the Doui Thabet forest (Mounts of Saida, West of Algeria): Pinus halepensis, Pistacia lentiscus., Tetraclinis articulata, Juniperus oxycedru,. and Stipa capensis (= S. tenacissima L.) between 2018 and 2020. An experimental field device covering an area of 1 ha has been installed in the Doui Thabet forest in a Pinus halepensis massive more than 80 years old. The following work was carried out: mechanical grinding of the vegetation (chopping), turning (scarification of soil) to a depth of 10 cm, tillage (Deep ploughing) to a depth of 20 cm, controlled burning of branches, clearing of Stipa capensis, seedlings planted in different seasons for certain species (Stipa capensis = S. tenacissima L.), monitoring of stump rejections and natural sowing. The sowing result varies according to the species and restoration techniques, it is high for Pinus halepensis and Stipa capensis. It is low for Tetraclinis articulata and Juniperus oxycedrus and none for Pistacia lentiscus while for Stipa capensis it is quite high when planted in autumn compared to spring. Turning and burning have proven to be the most abundant treatments for regeneration and growth. Grinding has medium seedling density and growth, while deep tillage and natural sowing showed low seedling density and growth.

Abstract

The forest of Doui Thabet is one of the forests of the Mounts of Saida (Western Algeria) which is experiencing a dynamic regressive. Located in the semi-arid bioclimatic stage, it is located at the edge of two phytogeographic sub-sectors: atlas Tellien Oranais (O3) and high plateau subsector (H1). Among the factors that threaten to curb this fragile and weakened ecosystem, in addition to drought and climate aridity and which has become a structural ecological phenomenon; the overgrazing is also a major limiting factor. This current study provides a qualitative and quantitative assessment of anthropogenic pressure exerted in this area zone. The methodology adopted in this study is that of Le Houerou (1969) and Montoya (1983), which it is based on the calculation of the annual needs of the herd in forage units, the estimate of the feed potential of production, the coefficient of overgrazing and in addition to the anthropogenic pressure index. The result of the forage balance in the forest rangelands of the studied area has a forage deficit (overload) of (96.64%) (a sylvopastoral imbalance), in addition to that, the coefficient of overgrazing is (92.3%) and the anthropogenic pressure index is very high (28). The conservation and the restoration of this area is a major concern in the face of global changes, taking into account their mode of reproduction and their dynamics, for the development of restoration strategies and more effective ways of protection.

Abstract

The East Balkan Peninsula Area was a part from the Tethys Ocean until 72 000 000 years. The pre Maestrichtian geologic-tectonic pattern of cockle of the East Balkan Peninsula Area wasn’t built on the Europe Continental Massif. The modern East Balkan Peninsula Relief is forming during the Late Quaternary time. The East Balkan Peninsula Margin coincides with the border between the Bulgarian and Moesian Continental Microplates from the west and the Black Sea Oceanic Microplatte to the east. This border present the Neo Europe West Passive Continental Margin in the area of the last Tethys Oceanic Fragment – it Black Sea Oceanic Gulf.

Abstract

The article introduces the results of the author’s new investigations about the origin, Quaternary morphotectonic evolution and the modern morphostructure of the Bulgarian Continental Microplate in the eastern part of Balkan Peninsula. The research was realized on a base of the contemporary Plate tectonic study principia by means of the morphostructural analysis apply. It was provided the principal relief building role of the regional mosaic pattern and the listric faulting in the Balkan Peninsula East Part.