Abstract
Plant translocation is the deliberate movement of plant material from a site or collection to a natural or semi-natural site. This increasingly frequent practice can be undertaken voluntarily, often in the framework of conservation programmes, but also as a mitigation measure, in response to legislation requiring the impacts on biodiversity to be considered in the framework of land use planning. In many countries, as in France, it is necessary to propose measures to avoid, reduce and compensate the impacts on the impacted populations of protected species. In the current French legislation, translocations are often proposed as a complement to the mitigation hierarchy.This thesis was funded by an environmental consultancy firm that is regularly confronted with mitigation plant translocations, which allowed me to gain a better understanding of this practice, the links between actors and the different issues at stake. The main objective of this thesis is to improve the practice of translocation by adopting a research-intervention approach, and by carrying out an assessment of knowledge of translocations in France, but also by experimenting and optimising translocation protocols on two case studies. In the first axis, the study of the perception of environmental actors in France about translocation, on the quality of the protocols proposed for mitigation translocations as well as on the monitoring effort put in place after translocation. These stakeholders have a rather mixed opinion on translocation (mixed opinion among all categories of stakeholders). This perception can be justified, since we have shown that the protocols for mitigation translocations lack details on the ecology of the species and are generally of poor quality. Moreover, we have also shown that monitoring is rarely carried out over the medium and long term, and experience sharing is rare. In the second axis, we studied two cases of mitigation translocations proposed in anticipation of a development project. We propose different methods to improve knowledge of a species and to optimise a translocation protocol. In the first case, targeting Helianthemum marifolium, we focus on the pre-translocation phase in order to acquire sufficient knowledge and to develop an ex situ phase in which individuals are grown. In the second one, focused on the species Serapias neglecta, we are optimising a translocation protocol by experimenting on a small number of individuals, in anticipation of a larger-scale operation.It is therefore urgent to study this practice and to improve its implementation. We propose various actions for improvement, some of which can be implemented by a consultancy firm, and others which require the state to take charge of the subject. These improvements are as follows: anticipate impacts during a development project, better integrate the experimental nature of a translocation, finance research-intervention, allow the mutualisation of translocations, couple translocation with management measures, share feedback and create a list of prohibitive species.