Dwarf bulrush (Typha minima Hoppe) populations in the Isere River: monitoring and restoration perspectives

Abstract

Over the last three centuries, river management has considerably transformed and artificialised the watercourses of the alpine piedmont rivers. 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. The study of the ecological niche of T. minima at the 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 banks with gentle slopes at elevations slightly above the average water level. Concerning the transplantation methods study, early trends suggest that the three types of transplants tested, namely containers, buckets and bare roots, can lead to the establishment of viable populations, even if containers and buckets give better results the first year.