Study of the plant recolonization process in a burnt heathland using a method of hierarchical classification

The reinstallation of different plant-species and their evolution during a ten-year period in a heathland after a fire accident has been studied by using the algorithm of heirarchical classification based on correlation (ABC) introduced by Tallur.¹ Classification under contiguity restraint of the set of observation points (subintervals of an experimental observation line) enables one to determine the ‘patches’ having uniform vegetation structure. Lerman's ‘local’ and ‘global’ statistics are used to condense the classification tree to its significant nodes and to choose the most significant partition. x² statistics are proposed to test whether a given patch has a ‘significant’ vegetation structure and if the association between a patch and a plant species is significant. Evolution of the horizontal structure of vegetation is studied by comparing the sets of patches obtained at successive observation dates and the corresponding dominant species.