The Mediterranean basin has been recognised as one of the world’s 25 biodiversity hotspots for priority conservation, accounting for more than 25,000 plant species, around half of which are endemic. In particular, the Tyrrhenian islands and archipelagos are characterized by an extremely high degree of endemism.

The National Park of La Maddalena archipelago (Italy), located between northeast Sardinia and southern Corsica, is considered a micro-hotspot, hosting more than one thousand vascular-plant taxa, 54 being Sardinian endemics. This archipelago comprises 7 major islands and 55 small islets, covering a land area of around 5,134 hectares. While the islets are characterised by rocky and dry sites unable to support woodland or forest, the main islands are covered with dense evergreen forests of Quercus ilex and Juniperus phoenicea, mixed with several shrub species typical of the Mediterranean maquis such as Arbutus unedo, Cistus spp. and Erica arborea as understorey layer. Different vegetation types, including heath, scrub-heath with or without low trees and thicket, generally consisting of shrub species approximately 1 m or less in height occur in lower-laying sites and sites more exposed to winds, with A. unedo, J. phoenicea, Olea europaea var. sylvestris, Phillyrea angustifolia and Pistacia lentiscus as the main components. Because of its unique habitats, the archipelago of La Maddalena has been declared as a Site of Community Importance and Special Protection Area for biodiversity conservation (Council Directive 92/43/EEC).

This type of ecosystems are also characterised by a greater vulnerability, as small geographic ranges combined with small population sizes may result in high inbreeding, low genetic variation, strong genetic drift and other stochastic factors. Human activities, such as the introduction of exotic and invasive plant pathogens can affect the diversity, richness, composition and abundance of plant species on islands. Since 2010, in the National Park of La Maddalena archipelago, extensive dieback and mortality of a wide range of plant species, typical of the Mediterranean maquis in the archipelago as well as in other maquis sites in Sardinia, has been recorded across slopes downhill of roads and trekking paths. These epidemic events, which have been associated with an unexpected high diversity of new and exotic Phytophthora species, are dramatically affecting the conservation of this unique ecosystem.

Consequently, the next International Union of Forestry Research Organizations (IUFRO) Working Party 7.02.09 ‘Phytophthora Diseases of Forest Trees’ congress will be held on La Maddalena Island from the 17th to the 25th of October 2019, with the overall aim to bring together scientists and experiences from all over the world, contributing to the progress of knowledge on Phytophthora disease as well as improving and sustaining forest health.

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