Influence of the sanitary state of acorns on the regeneration of Quercus suber in Tunisia

In Tunisia, Cork oak forests represent ecosystems of fundamental ecological importance for the preservation of genetic resources and for environmental protection at both national and global scale. They present numerous assets in touch with their great biological diversity and their impact on the environmental and socioeconomic balance. The object of the present study was the characterization of the natural regeneration of Cork oak and of the action of insects on acorns. It allowed us to spot certain parameters linked to the biology and to the ecology of the Cork oak generally and to the acorns in particular, in North-western Tunisia. We determined the various biometric parameters of acorns according to whether they were healthy or affected by insects, such as length, diameter and weight of acorns coming from different strata of harvests and different exposures. We showed that acorns affected by insects have their length, diameter and weight lower than the non-affected healthy ones. The importance of the attacks of acorns by insects explains partially the deficiency of the natural regeneration of the Cork oak observed in our forests. This situation causes modifications at the level of the structure, diversity and density of seedlings. Our results allow recommendations for the natural regeneration of cork oak: (i) for the seedling by acorn use non-attacked acorns and avoid collecting acorns which had fallen on the ground; (ii) use also the technique of rejections of origins.