Abstract : Through this investigation, a geographical method to evaluate "crisis narratives" about environment is proposed. Theses narratives are discourses which define the state of the environment as unsatisfaying, or far away from a "normal" situation. Historical genesis and global functioning of these judgments should be understood, as they form the theorical frame of representations and actions that structure environmental policies. Taking the example of Uruguay (South America) from XVIIIth to XXth century, the aim is here to verificate how pertinent are the narratives which state that the forests of this territory have been destroyed by the european colonizers. In a first step, we identify historically theses narratives, and demostrate the territorial stakes that underlie them. We then show, by handling simultaneously historic, naturalistic and biogeographical methods, that these narratives are only very little in adequacy with the observable processes. Finally, we propose the explanations aiming to understand how, in Uruguay, forests of small size were able to maintain their surfaces during three hundred years, in opposition with the crisis models. By a territorial and landscape vision of the forest evolution, centered on the actors, we relativize the importance of the crisis denounced. This consideration aims to define the best way to put in adequacy the method of assessment with the narrations that it is being analized.