The concepts of plant architecture are powerful tools for understanding plant development over time and the growth strategies of species in their environment. The architecture of plants depends on the nature and arrangement of each element and is, at a given time, the expression of a balance between endogenous processes of growth and the constraints exerted by the environment. Our work is a contribution to the health monitoring of our forest Chettaba (Algeria) which is currently done at the scale of the tree, within plots of small area (4 plots), by an original method of visual diagnosis of oaks is used (ARCHI method). To assign an Archi type to a tree, a diagnosis of the development and physiological state is made. The diagnostic results show that the holm oak in the studied plots is currently in a healthy state despite the presence of trees with degraded crowns with impoverished branching, abnormal mortality and without any viable restoration process such as substitutes, which cannot be chosen as a future tree. The holm oak of Chettaba forest is classified as a viable ecosystem, with a good probability of remaining alive.