Introduction

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Mediterranean Island plants

The Mediterranean basin contains nearly 5,000 islands and islets. While many of these are quite small (4,000 cover an area of less than 10 km2), there are also many larger islands such as Sicily (with an area of 25,700 km2). This great diversity in island size as well as differences in altitude and geology means that a large number of habitats are represented in the region. Different geographic situations (some islands are close, and others far away from the mainland), and their geographic history (some islands have been isolated for a long time, and others not), have produced a flora of exceptional diversity. In addition, many Mediterranean plants are closely tied to traditional human activities which maintain this species richness.

Nearly 25,000 species of flowering plants and ferns are native to the countries surrounding the Mediterranean basin, and 60% of these plants are found nowhere else in the world. This extreme richness means that the Mediterranean is considered one of the world’s 25 biodiversity “hotspots”.

Thanks to their isolation on islands, some ancient plant species have managed to survive while their relatives on the mainland became extinct. This is because some mainland species could not compete with the migration into their habitat of new species, mainly caused by climate change during the last glacial periods. Because natural exchange of genetic material between the island and mainland species has been limited or non-existent, successive mutations caused the gradual formation of new species unique to each island.

The number of “endemic” species, that is those which are only found on one or a group of islands, is therefore very high. On the larger islands, around 10% of the species are endemic or unique to the island.

These endemic species are often very localised and have a small number of individuals, which makes them particularly susceptible to extinction. The Top 50 presented in our booklet and on this site have been selected from these many rare and threatened species.

The IUCN Red List Categories and Criteria

To evaluate whether or not a species is threatened, scientists measure the likelihood of extinction for each species. To do this they note whether or not the species is declining, either in number of individuals, or if the area in which it is found is getting smaller. They also take into account extreme population fluctuations because if the number of individuals is very small, a sudden change could drive the species to extinction. The Species Survival Commission has developed the IUCN Red List Categories and Criteria, designed so that the threat level for all living species may be measured using precise, quantifiable criteria. The eight Red List Categories are as follows:

• Extinct (EX)
• Extinct in the Wild (EW)
• Critically Endangered (CR)
• Endangered (EN)
• Vulnerable (VU)
• Lower Risk (LR)
• Data Deficient (DD)
• Not Evaluated (NE)

To chose to which Red List category a species belongs, a series of criteria have been developed, and these have been listed for each species in the “Why is it threatened?” section. These criteria range from A to E, with subcriteria from 1-4, a-c, and i-v. A species must meet one or more of these criteria to qualify for the category. As it is too complicated to explain how the criteria are used in this short introduction, readers who are interested are advised to read the IUCN Red List Categories and Criteria (ver. 3.1) available from IUCN or on the web.

The list of the threatened species of a country or a region is called a Red List. The Red List measures the “state of heath” of biodiversity, noting why species are threatened and what conservation actions are needed to improve their situation. Red List assessments are regularly reviewed in order to monitor if a species’ status is getting better or worse, and what new action may be needed to reduce the risk of extinction. Assessment of the conservation status of the plants of the Mediterranean Islands is an important first step in planning conservation activities and in ensuring sustainable use of these species.

Criteria for selecting the Top 50 Mediterranean Island species

The 50 species presented in this booklet were selected according to a number of criteria. These include level of threat, regional representation, an agreed taxonomy, and representation of different plant families and life forms. A mushroom species, which technically is classified as a fungus and not a plant, has been included to further represent the diversity occurring in the Mediterranean.

Sadly, many more species than those listed in this booklet require urgent conservation measures. The IUCN/SSC Mediterranean Island Plant Specialist Group, in collaboration with scientists and Red List activities taking place in all the countries in the region, is continuing to identify threatened species and propose conservation actions to ensure that the conservation status of the unique and beautiful flora of the Mediterranean Islands improves. Additional species sheets will be added to the Group’s website gradually and the status of species already listed in the booklet will be monitored.

The species are found on 12 islands or island groups. While most (46) are classified as Critically Endangered (CR), examples of a species evaluated as Extinct in the Wild (EW), Endangered (EN) and Data Deficient (DD) are also included.

Threats to the Mediterranean flora

The main factor raising the risk of extinction for the 50 species listed in this booklet is linked to the size of their population and their distribution. In almost every case, due to the small number of individuals or tiny area of distribution, any major disturbance (for example, fire or construction work) might just push the species to extinction or seriously reduce its chances of survival. For four of the species listed, less than 50 individuals are known in the wild.

In addition, when the number of individuals in a population falls below a certain threshold, the species loses genetic diversity which reduces its ability to adapt to change, and therefore further increases its extinction risk.

The main threats faced by the species evaluated in this booklet are mostly due to direct or indirect human activities. These fall under the following categories (in decreasing order of importance):

It is also clear that climate change will increase these threats. In effect, not only are plants by their nature relatively immobile, it is also difficult to change altitude if the species relies on specific ecological conditions. Island floras also have limited scope to migrate horizontally, especially on small islands.

Recommendations for conservation action

Nearly three quarters of the 50 species selected for this booklet benefit from some sort of legal protection, whether at a national or international level. About half have some or all of their population included in a protected area. However these conservation measures, while very valuable, are often not sufficient to completely reduce the risk of extinction.

Half of the species listed are conserved in botanical gardens or seedbanks (known as ex situ conservation or cultivation), but there is no guarantee that if the species disappears in the wild, it will be possible to reintroduce the species or to maintain its genetic diversity in the long-term. It is in all cases preferable, and certainly less costly, to try to maintain the species in its natural habitat (known as in situ conservation). However, when a species does become threatened, cultivation can serve as an “insurance policy” in case the species becomes extinct in the wild. A good example of this is Diplotaxis from the island of Alboràn. The species disappeared from the island but has been reintroduced using cultivated plants.

Conservation for each species requires specific, targeted actions. These are outlined in each datasheet and fall under the following categories (in decreasing order of importance for the 50 species studied):

The planning, financing and implementation of conservation measures require substantial resources that can only be put into place by decision-makers, managers and the public who are convinced of the importance and relevance to people. It is therefore essential to increase the public’s awareness about the importance of plant conservation, and its fundamental value to human well-being.

Structure of the species datasheets

The 50 species are presented in alphabetical order of the islands or groups of islands on which they are found, and within that group, in alphabetical order by Latin name. Because some species have many common names and others none, the species have been listed according to their Latin name. In cases where experts disagree on the Latin name, another name by which the species is also known (synonym), has been listed.

This work presents a selection of 50 of the most threatened plant species growing on Mediterranean islands. It aims to draw the attention of both the public and politicians to the vulnerability of island floras in the Mediterranean, and calls for urgent conservation measures. The impact of increasing human activity and changes in agricultural practices must not lead to the extinction of these and other species.

As this work is aimed at the lay person, the text has been made as simple and non-technical as possible. Readers who wish to learn more about the species highlighted here, or on plant conservation in general, can refer to the references, go to the map, or consult the species list.

For further information contact:

Bertrand de Montmollin
Chair, Mediterranean Island Plant Specialist Group
Rue de la Serre 5, CH-2000 Neuchâtel, Switzerland
gspim@biolconseils.ch

Wendy Strahm
Plants Officer, Species Programme
IUCN - The World Conservation Union
Rue Mauverney 28, CH-1196 Gland, Switzerland
was@iucn.org