For the European Union, conservation of Sycamore maple (Acer pseudoplatanus L.) habitats is a priority issue EUR 9180, appendix I, forests of slopes, screes and ravines of the Tilio-Acerion alliance. In our study, we propose to assess both dynamics through a synchronous method and ecological value through a multicriteria stand-level method (Du Bus de Warnaffe et Devillez, 2002) in order to fully understand the conservation issues of these rare habitats. The results of this study shows: (i)Differences in dynamics depending on the nature of the substrate for the Sycamore habitats; (ii)Difference in the ecological values for the Sycamore habitat and for the mixed Beech-Fir-Spruce forest. Then, we discuss the limits of the dynamics assessment, principally due to: the specificity of forest species, the human influence and the limits of the synchronous approach. Furthermore, the multicriteria method confirmed the empirical ecological value given by naturalists to Sycamore habitats. We brought simplifications to make the method accessible to forests managers and technicians. All in all, we insist on the necessity to have an exhaustive knowledge of a habitat before considering its conservation. Simple and reproducible methods of assessment seem to be the relevant way to reach conservation of biodiversity goals.