A regional floristic and phytogeographic study was conducted in the Mounts of Saida, a subsector of the Tell Atlas (Oran) (O3), in the western Algeria. On an area of 56.31 Km 2 surveyed regularly over time during the springs and autumns from 2017 to 2019. A total of 344 taxa divided into 77 families and 223 genera, including 18 new (exogenous) for Tell Atlas (Oran) sub-sector (O3), have been inventoried. Of these 18 species, 8 belong to the phytogeographic areas of the arid (H) and hyperarid (AS) regions and 2 invasive species that reinforce and confirm theories of plant dispersal to the north and to high altitudes for adapting to climate change. The Factor Analysis of Correspondences (F.A.C) shows that species distribution is the result of local microclimates associated with the elevation; particularly, the mountains facing north receive a significant amount of humidity from the Mediterranean Sea.

Soil water erosion is a major aspect of landscape degradation in sub-wet to semi-arid Mediterranean environments. This problem has not been dealt with in detail in Algeria although it affects large areas. The objective of this study is to develop a methodology using remote sensing, the digital terrain model (DTM) and geographic information systems (GIS) to map areas with a risk of water erosion within the territory of Saida province and to produce a risk map that can be used as a reference document by the local authority. The presented methodology consists to incorporate three factors controlling the erosion: slope, material friability and land use. The resulting erosion risk map shows five areas of vulnerability to water erosion: very low, low, moderate, high and very high. Areas with high and very high risk of erosion cover more than 20% of the mountainous area and are consistent with our field observations. The methodology presented in this study can be generalized to all areas of the foothills of the Tellian Atlas, where erosion risks pose a threat to urban areas. This model is a tool to help implement a soil conservation plan in order to organise the measures to be applied and ensure sustainable soil management.

Juniperus oxycedrus L. and Pistacia lentiscus L. are two taxa with a rigid or rigid enough structure caused by a solid pericarp resulting in a strong inhibition of the germination. The objective of this work was to test the effectiveness of certain pre-germinative treatments on the germination rate of the Juniperus oxycedrus and Pistacia lentiscus seeds with the aim of restoring perturbed ecosystems. In this context 180 seeds from each of the 2 examined species were tested in the laboratory (the number of repetitions is 5, to reach the degree of freedom 'ddl'). The seeds were divided into 4 groups of 20 seeds of each species and were treated as follows: 1) Immersion in the concentrated (95%) sulphuric acid (H2SO4) for 10, 30 and 60 minutes; 2) Mechanical scarification with a scalpel; 3) Soaking in hot water (at 100°C) for 30 seconds, 60 seconds and 2 minutes; 4) Cold stratification at 5°C for 24 hours. There is also a control group of 20 seeds representing each of the two species, which remained neutral. In the case of the Juniperus oxycedrus seeds the results showed that the germination rate improves after the mechanical scarification with a scalpel (92%), followed by the cold stratification with water (86%) and a treatment with a concentrated sulphuric acid for 60 minutes (82%). The seeds were treated with H2SO4 for 10 and 30 minutes, respectively, soaked in hot water; the control lot did not germinate. The germination rate for the Pistacia lentiscus seeds is 88% after the mechanical scarification and 84% after the cold water stratification. On the other hand, the treatment with H2SO4 or after soaking in hot water does not allow for the germination of these seeds. The same result is observed on the control group (0% for 30 days).

Beneficial Autochthonous Microorganisms (BAMs) are a multi-purpose technology that has already been used in Latin America and Southeast Asia but is still unknown in Africa and particularly Algeria. The aim is to examine the effect of BAMs on agricultural soils and olive fields. The study was carried out in two degraded olive fields located in the Oued Tafna basin west of Tlemcen (The Semi-arid region in Western Algeria). The objective is to evaluate the effectiveness of BAMs on the chemical characteristics of the soils, particularly in terms of organic matter (MO), pH, electrical conductivity (EC), total limestone (CaCO3), moisture, organic carbon (C) and olive production and its weight. Statistical analysis (Independent Test) between all groups (treated and controls) showed a significant difference, in conductivity (EC) where we recorded “0.214±0.03μs /cm “ in treated soils vs. “0.198±0.029μs/cm “ in control soils a different statistical significance was recorded for the other parameters, however, it was observed that there is a relative increase in these parameters in the soils of the treated groups such as carbon (C): “2.85±1.06%” organic matter (MO): “4.91± 1.83%”, “pH=7.81±0.225”, “CaCO3 27.76±4.99% and a decrease in humidity “15.11±3.77%” compared to control soils. The results of statistical analyses (Mann-Whitney Test and Suite Test) of olive production showed a clear alternation (every other year) in fruit production in the control group and a positive effect of BAMs on olive production in the treated group, with a slight increase of production (19 kg in 2019 vs. 30 kg in 2020), but without any significant difference regarding the weight of the fruit between the two sessions. However, a highly significant difference “p=0.00<0.001” in fruit weight was noted between the treated groups “3.908g” and “5.70g” and the control ones “4.40g “ and “5.00g” in 2019 and 2020 respectively. The use of MAB is an interesting technique to restore the chemical properties of degraded soils, and increase olive tree production. To achieve more reproducible results (in terms of quantity and quality), sufficient doses of these BAMs and periodicals must be added to provide a good nutritional supplement and reduce farmers’ use of pesticides and mineral fertilizers.

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