ABSTRACT :
This work summarizes the results of the botanical and phytoecological study performed on the five islands and islets of the Kneiss archipelago (South-East Tunisia), during a mission of the PIM Initiative in April 2015.
The history of this micro-insular environment highlights the deep physiographical changes induced by sea level rise since few thousand years. Add to this, the impacts of human and his cattles have caused the local extinction of several shrubs and palatable plants formerly censused on the main island, El Bessila or Grande Kneiss. These pressures have profound consequences on the current state of flora and on the structure and dynamics of vegetation. The floristic impoverishment results in a very low species richness, with only 74 taxa currently censused on El Bessila (c. 436 ha), and 9 taxa for the four islands representing a total area of less than 1 ha. However, there are several taxa of the Saharan or Saharan-Arabian contingent, which are very interesting on the phytogeographical point of view and that must be preserved. The vegetation study has identified 10 types of plant communities on the island El Bessila which is largely covered by halophilous thickets characteristics of the vegetation of sansouires.
Despite its status of Nature Reserve since 1993, the general state of conservation of the terrestrial plant biodiversity of the Kneiss archipelago is considered as worrying. Some actions to preserve and restore the remaining phytoecological capital should be undertaken in the short-term.