Impact of different factors degrading cork oak stands in the Mediterranean region: A case study from Algeria

In recent years, the cork oak forests that characterise the Mediterranean region have been exposed to various factors that result in their degradation. These cork oak trees, due to increasingly accentuated anthropogenic activity, undergo withering at different scales.The objective of the study is to assess the impact of various factors that degrade cork oak forests in the Mediterranean region located in northeastern Algeria, and this was achieved by prospecting 22 sampling locations. This allowed the creation of a database containing 745 trees that were observed and 27 measured variables. Different readings were then taken into consideration based on measurements and sometimes on ratings. The impact of several biotic and abiotic factors, which affect and damage the health of cork oak, was identified. These factors include in particular the infestations by xylomycetophagous insects such as Platypus cylindrus and Xyleborus sp., which can potentially infest the cork oak trees that we observed one year after bark harvesting. On the other hand, the stationary descriptors such as altitude, slope, exposure, etc., are important for the dendrometric and exploitation characteristics, but their unfavourable values do not necessarily lead to tree mortality; for example, medium to low slopes, associated with average altitudes of 600 m a.s.l., may ensure the healthiest trees like in our case study. Finally, we were able to find that certain decline factors may affect a particular category of trees, either because they are older, taller or have a large girth, or because they are subject to inadequate debarking.