Résumé: The cork oak (Quercus suber L.) forests are ecosystems of high environmental and socioeconomic value in the Mediterranean basin. However, in Algeria, the cork oak forests are highly threatened by repeated fires, overgrazing and the anthropogenic pressure that weaken the ecosystem of cork oak and affect its natural regeneration. This degradation results in an alteration of many ecological components of the cork oak, such as fungal communities in the soil. Thus, the aim of this work is to study the effects of cork oak stand degradation on the diversity of mycorrhizal communities associated with Quercus suber and some of its understory shrubs (Cistus monspeliensis, Lavandula stoechas and Thymus vulgaris) in the forest of Brabtia (northeastern Algeria).For this purpose, two sites were chosen: one degraded by the anthropogenic factors and the other non-degraded one. Moreover, it is suggested that some plants of the understory shrub vegetation of cork oak, such as the cistus, lavender and thyme, prove to be favourable to the juvenile growth of this tree. The results obtained showed that the ectomycorrhizal (EcM) root colonization of cistus was higher compared to that of cork oak in both stations. The estimation of arbuscular mycorrhizal (AM) colonization showed significantly higher levels in the roots of cork oak, cistus, lavender and thyme in the degraded station compared with the non-degraded stations. In contrast, the rhizosphere soils of cork oak and cistus had low number of AM propagules and fungal spores, while under the roots of lavender and thyme, these two parameters were greatly improved with the abundance of the genera Glomus and Gigaspora. These results underline the need to take into account the plant–fungus interactions in the development of restoration strategies of the degraded soils and forest ecosystems.

Résumé: Water plays a crucial role in the life and development of humanity. Since time immemorial, people have settled near water points, which have always been a source of life and well-being. For thousands of years, it has been celebrated and recognized as a sacred resource. Today, due to rapid population growth, economic development and other challenges that affect natural resources, water has become a precious commodity. To this end, the objective of our work is to know the chemism of the groundwater of the lower valley of Oued Bounamoussa Willaya of El Tarf (North East Algeria) and to diagnose the origin and intensity of the pollution that degrades this water resource. A sampling of water was carried out in February 2021 on all the length of Oued Bounamoussa (Upstream, Center and Downstream), of which several physico-chemical parameters were carried out such as; pH, EC, SS, NO-3, NO-2, Cl-, P2O5. The results obtained show the presence of a very important pollution rate in the groundwater of Oued Bounamoussa, which pollution has several origins namely urban, agricultural and industrial. So this water resource has become a danger and risk on the health of living beings and on the intoxication and it disturbs the sustainable development.

Résumé: The cork oak (Quercus suber L.) is a tree which forms important forests that play a vital socioeconomic and environmental value in the Mediterranean basin. The multiple factors of overgrazing, biological invasion by introducing acacia trees, and repeated fires weaken the cork oak ecosystem and affect its natural regeneration. The purpose of this study is to increase the production of cork oak. With this aim, a test of controlled mycorrhization was carried out on the nursery where two commercial inocula—the arbuscular mycorrhizal (Symbivit) (S) and ectomycorrhizal (Ectovit) (E)—were brought separately and combined on cork oak seedlings cultivated on sterilized or non-sterilized soil. Statistical models revealed that the controlled inoculation improved the growth of the plants inoculated by IE, which had significantly increased mycorrhizal root colonization levels and cork oak growth compared to the treatments of the Symbivit (IS) and the non-inoculated plants (NI); these rates were lower in both substrates: sterile and non-sterile. It is known that the best mycorrhizal partners of cork oak are ectomycorrhizae, however, in the presence of arbuscular mycorrhizae, the mycorrhizal root colonization levels and the growth parameters were considerably enhanced compared to previous treatments IE, IS and NI. The dual colonization had shown positive effects on the improvement of the mycorrhizal potential of the soil. Indeed, EM % colonization was the most strongly correlated with growth parameters compared to other mycorrhizal parameters. This research underlines that the use of controlled inoculation based on commercial inoculum can be an effective alternative in the case where the local inoculum is not available, and thus time saving

Résumé: Some plants of the cortege floristic of the cork oak, such as the case of the lavender in this study may be favorable to the juvenile growth of cork oak. Thus, plants nurses facilitate the ecological restoration of forest areas degraded greatly, mycotrophic, which can ensure the restoration of mycorrhizal power of soil, thus favoring the good development of the plant cover. The objective of this present study was to evaluate the synergistic effect produced by the presence of plant nurse (Lavandula stoechas L.) and the inoculation of mycorrhizae (Ectovit and Symbivit) on the growth of cork oak. For this purpose, a test of controlled mycorrhization in the nursery has been realized on a twenty plants of this plant grown in polyethylene bag in the presence or absence of lavender (Lavandula stoechas L.) based on plant of cork oak and 10 plants of lavender per bag. The substrate is a soil came from the cork oak forest of Brabtia (Northeastern Algeria), whose condition is well degraded. Non-inoculated controls with and without lavender were provided. After 12 months of growth, the statistical study according to the LSD test showed that cork oak inoculated and not in the presence of lavender had the highest rates of mycorrhization, respectively, 49.59% and 43.66% the same for the total biomass such as 25.02 g and 19.55 g compared to the treatments in absence of lavender as 15.63 g and 12.59 g.