Adaptation of cork oak (Quercus suber L.) forests in Algerian western region facing climate change


Abstract: West Algerian cork oak forest stands are mainly found in the Hafir (Tlemcen), Nesmoth (Mascara) and M’sila (Oran) forests, while some remnants still persist in the provinces of Mostaganem, Tiaret, Sidi Bel Abbes, Relizane and Ain Témouchent. These formations are nowadays of great interest from an ecological and phytoecological point of view due to their very different morphological aspects. This variation relies to an adaptive flexibility of the species to adapt to habitat (climate) or genome (hybridization) changes. Preservation remains necessary and even indispensable in terms of its impact on biodiversity. In this context we examined the morphometric characteristics of the different Q. suber stands located in the western Algerian region and whose systematic and taxonomic position remains uncertain. We are particularly interested in the quantitative and qualitative aspects of these stands, taking into account two variables related to the station (habitat) and variables related to trees (structural and architectural parameters). Morphological and biometrical observations on leaves and acorns were made in four different stations representing the major cork oak stands in the region. The evaluation method was based on a random collection of leaves and acorns in areas of 0.04 ha including an average of 12 to15 trees each. In each forest 10 plots were installed in two stations (five plots per canton). As a whole about 400 trees were sampled. Five characters (length, width, number of spines, number of stomata and leaf area) of the leaves were identified and measured, and three characters (length, diameter and weight) for acorns. The analysis showed a noticeable inter- and intra- populations variation in these parameters. This led us to confirm the presence of different populations of Quercus suber. The marked polymorphism of this species corresponds to its high adaptability to environmental conditions that would result in a variety of responses of leaves and acorns to these conditions. We observed that the populations in drier areas have narrower leaves with longer spines and lighter and smaller acorns.

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