The preservation of biodiversity represents a well-established priority in global environmental policies and is a key component of the main international strategic plans (i.e. the Global Strategy for Plant Conservation, the Aichi Biodiversity Targets, and, at European level, the ‘‘Habitats Directive”). However the loss of biodiversity is constantly increasing mainly by the continuous and growing human-related impact (i.e. pollution, global change, industrialization, urbanization and consequent “waste of land”).
The Mediterranean Basin hosts a flora of around 25,000–30,000 flowering plants and ferns, c. 50% of them are endemic plants; in particular the aisled geographically or ecologically territories, such as islands, islets, and mountains, constitute the main centres of plant diversity. However, this plant richness is severely threatened and it deserves particular attention in a conservation point of view.
Ex situ strategies (i.e. conservation of species outside their natural habitats), to date, represents one of the most e ective ways to conserve plant diversity. Germplasm preservation include seed banks, pollen and tissue storage, vegetative cloning and maintaining whole plants, which allows preserving large amounts of genetic material in a small space. Optimistically, ex situ conservation could reach significant levels in the coming years (at least in some territories worldwide) and with accessions representative of natural variability. However, the main question is how to use these accessions for future conservation activities (if necessary).
In situ strategies (i.e. conservation of species in their natural habitats) is considered the most appropriate way of conserving biodiversity and the preservation of the areas where populations of species naturally exist is an underlying condition for their conservation. The importance of in situ conservation of endangered plant species has been highlighted by the Target 7 of the GSPC for 2020 which scheduled that at least 75% of known threatened plant species should be conserved in situ.
Conversely, despite the importance of the in situ measures, their full application remain far from being widely achieved. To prevent the extinction risk of threatened species and to improve their conservation status, translocations have become increasingly important in management worldwide and they represent the ideal scenario although it is not often practicable. Translocations (including population reinforcement, reintroduction and introduction) aim to enhance population viability, for instance by increasing population size and/or genetic diversity. The potentiality of translocations to contribute to the recovery of threatened species is particularly significant when is a part of integrated ex situ and in situ conservation activities. In particular when seeds stored ex situ are the starting point for producing transplants to be reintroduced in the natural environment; the strong integration between in situ and ex situ conservation strategies is the emerging tools in the conservation of plant diversity .
However, many limits remain in the implementation of these conservation actions, such as the high both economic and time costs, the availability of the optimal site, the dificulties on the implementation of these actions on private areas and the high uncertainty of success principally connected to natural stochastic events. Thus, considering these several limitations, it is often necessary to identify other active management measures, such as the fences erection (to prevent grazing and to protect the most critical life-cycle stage for population survival) or to remove alien invasive plants, or to plan a low-cost translocation project. Although the active in situ conservation actions are the best way to conserve natural plant populations, very few experiences has been done in the Mediterranean territories compared to what is necessary to prevent the extinction risk of many plant species. Thus, taking into account the limited available economical funds and human resources, the implementation of the active conservation measures will be the first purposes.