Dwarf bulrush (Typha minima Hoppe) populations in the Isere River: monitoring and restoration perspectives | Les populations iséroises de petite massette (Typha minima Hoppe) : suivis et perspectives de restauration

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN

anglais. Over the last 3 centuries, the alpine piedmont rivers have been considerably transformed. Among the species present in these impacted environments is the dwarf bulrush (Typha minima Hoppe). Its most important populations are located in the French Alps rivers such as the Arve, Isère or Durance, where it is protected at the national level. As such, after avoidance and reduction, the residual impacts on its populations must be compensated. The restoration of populations of T. minima poses questions to which this article aims at providing some answers. T. minima ecological niche of T. minima on Isère shows that it is not possible to predict the presence of favorable habitats from Isère hydrogeomorphological characteristics. However, our results show that in order to optimize their survival, population transplantations will have to be carried out on benches with gentle slopes at elevation slightly above the average level of the water. Concerning transplantation methods study, early trends suggest that the three types of transplants tested: containers, buckets and bare roots, can lead to the establishment of viable populations, even if containers and buckets give better results the first year.

français. Pour se protéger des crues en montagne, les hommes ont transformé et artificialisé les cours d'eau, avec comme conséquence une perte en surface d'habitats pour la biodiversité. Ainsi, les populations de petite massette (Typha minima Hoppe), plante des berges des cours d'eau, ont régressé de 85 % en un siècle dans les Alpes ! Aujourd'hui, la législation est plus attentive à la préservation de la biodiversité dans le cadre de projets d'aménagement et elle rend obligatoire un certain nombre de mesures permettant de compenser les impacts sur les écosystèmes. Pour les aménageurs du territoire, la restauration de populations de T. minima pose cependant des questions auxquelles cet article apporte des éléments de réponses.