La hiérarchisation des unités forestières et des bois en milieu urbain sur la base de leur valeur ecologique

Abstract

An original methodology used for the assessment of urban woodlots within Montréal Urban Community is described and discussed. The methodological approach adopted has three main characteristics. First, it is based on the ecological value concept. Secondly, it emphasises explicit and quantitative criteria, and thirdly, the evaluation is made at two levels: forest units and woodlots. Evaluation criteria based on previous work reported in the literature are presented for both levels. Presence of rare plant community types, representativity, successional and disturbance status, abundance of rare species and species richness were used at the forest unit level. At the woodlot level, the global ecological value of each forest unit, plant community diversity, woodlot area and woodlot integrity were used. For each of these criteria, one or many indicators were used to quantify the field data. The results suggest that the progress made so far in the definition and measurement of criteria has led to an appreciable increase in the validity and usefulness of a quantitative approach in site assessment. However, serious difficulties persist with regard to the ecological value concept itself and to the weighting of criteria.