Etude de la viabilité de quelques espèces feuillues de l’arboretum de Draa naga (Constantine, Algérie)

Abstract – The arboretum of Draa Naga is for forestry, educational and ecotourism purposes. Managed by the Forest Conservation of Constantine, this site is made up of 77 plots where are planted several silvicultural species (hardwoods and conifers) of various origins spanning an area of ​​30 ha. Following a decision by the Forest Conservation of Constantine for the conservation and restoration of the Draa Naga Forest Station, where no study has evaluated its viability since its establishment. The objective of this study is to estimate this viability by continuously monitoring the current state of the arboretum, including biodiversity and pressures. The collection of related data used a forest inventory (foot per foot) and an inventory of pressures. The condition was evaluated by analyzing these components. The various analyzes conducted in this study on a few hardwood species revealed that the arboretum is subject to biotic and abiotic pressures and average viability. This is induced by fairly good stand quality (PHF = 223), average stability (FE = 42.48), high mortality (over 33%), and average future potential (low regeneration rate = 47%) . Grazing, fire and illegal logging are the most important pressures. Despite these pressures, the arboretum is classified as a viable ecosystem. But these potentialities are insufficient: we must reduce pressure and rebuild the arboretum for better conservation of the ecosystem. To this end, the present study suggests management first by silvicultural interventions favoring the regeneration of different species and to include a permanent ecological monitoring system. The latter allows to frame all interventions.

Keywords: Hardwood, viability, arboretum (Draa Naga), pressures, ecological monitoring.

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Régime thermique et analyse de l’adaptation des arbres forestiers à la contrainte thermique

Abstract - Climate change refers to changes in the climate of the earth as a whole in terms of temperature, wind patterns and precipitation. These changes have accelerated in recent years. The effects are felt on the physiology of the plants (metabolism, growth, phenology, photosynthesis, respiration) on the distribution and the increase of the different stresses notably by an intensity of heat waves, floods and other catastrophes. This thermal variability has been studied in the region of Sétif. In recent decades, the analysis of regional climate change has become one of the concerns of the scientific community. Our study consists in analyzing the thermal data of the Setif region over a period of 8 years between 2000 and 2007. The analysis of the hourly, maximum and minimum temperature, shows that the thermal stress is greater in summer with durations included between 78 and 78 hours. The evolution of seasonal tri seasonal temperatures shows that the variability is especially important in winter (69%) followed by spring (47%), autumn (40%), and summer with 23%. The average annual thermal spectrum with 43479.3 ° C shows that summer represents 42.82% of the annual cumulative, followed by autumn (26.06%), spring (21.96%) and winter (9.16%). The thermal regime of the Sétif station is of the EAPH type, switching between spring and autumn. The annual thermal variability shows that the year 2001 is the hottest, estimated at 1850 ° C with a mild winter season, while the year 2005 is the coldest with an estimated cooling trend of 1599 ° C.

Keywords: Thermal regime, climate change, Setif.

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Diversité physiologique des réponses des jeunes plants de chêne liège (Quercus suber L.) au stress hydrique en Tunisie

Abstract – The cork oak is the native forest species, the most represented in Tunisia especially Mogods and Kroumirie. This species is in considerable decline, estimated at 1.22% of the area per year (Abid and Selmi, 1998). The natural regeneration of cork oak by sowing and by stump rejection, encounters great difficulties, especially because of the high mortality in young plants. The failure of this regeneration is mainly caused by the environmental conditions characteristic of the Mediterranean climate (long dry seasons with hot winds, and high temperatures), as well as by predation and anthropogenic factors. Our study consists of adaptation to drought at the juvenile stage to determine markers of drought resistance. For this, a study of the physiological and biochemical responses of cork oak seedlings, subjected to moderate and severe water stress, was conducted in nurseries in Tunis in twelve cork oak populations in Tunisia. We have determined water parameters, physiological.

Keywords: Cork oak, water stress, adaptation to drought, physiological markers, tolerance and avoidance.

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