Abstract
Based upon architectural diagnosis, four tools are available to diagnose the trees and assess their reactivity to environmental disturbances. The ontogenetic diagnosis tool, already implemented, makes it possible to identify the stage of development of the tree. Architectural markers list the criteria to describe a tree and its vitality. Identification keys ARCHI are used to predict the short term future of trees showing symptoms of dieback. The DiagArchi application, under development, will be a teaching tool to familiarize the user with the required pre-morphological knowledge, and technology to automatically get the results to diagnosis. These tools could help in forest management and in decision-making intervention at periods of tree decline.