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Islands and plants: preservation and understanding of flora on Mediterranean islands

Table 4. The status of the terrestrial habitats (according to the 92/43 EU Directive) on
18 circum-Sicilian islets. P = present; T = threatened by direct human pressure; L =
localised; EX = extinct in historic times. Island abbreviations are provided in Table 3.

The history of natural and human disturbance
Besides earthquakes, tsunamis, and volcanoes, two other disturbance factors
have greatly affected the Sicilian landscape: herbivores and humans. Herbivores
could have affected the floristic assemblages of chersogenous islands (Greuter,
1991) like Favignana, Levanzo, and Lampedusa at least since the beginning
of the Pleistocene (Capasso Barbato et al., 1988; Bonfiglio et al., 2002), while
humans first occasionally and permanently colonized Sicily c. 35 and c. 20 Ky
BP, respectively (Tusa, 1994; Mussi, 2001). Human activities have influenced the
natural landscapes of the main circum-Sicilian islands since the Mesolithic (e.g.,
Levanzo) and during the Neolithic (e.g., Lampedusa, Pantelleria, Favignana,
Ustica, and the Aeolian Archipelago). Burning, clearing, cutting, farming,
ploughing, etc. not only fostered the success of many allochthonous pioneer
and helio-xerophilous plants now referred to as “archaeophytes” but also gave
rise to a complicated mosaic of prevalently open habitats dominated by sub-
shrubs and grasses (Guarino et al., 2005; Guarino, 2006). forest communities
were nearly erased, so that many woody species such as Acer campestre or
Quercus cfr. virgiliana disappeared during pre-historic (Poggiali et al., 2012)
or historic (Calò et al., 2013) times or are now threatened with extinction (La
Mantia & Pasta, 2005).
In recent times, and especially during the last 20–40 years, nearly all
Mediterranean islands experienced a strong decline in agro-pastoral activities.
Nonetheless, the frequency and intensity of past human disturbance still affects
the current plant communities, including the speed and the path of succession
(Quézel & Médail, 2003; Blondel, 2007).
Over recent decades, the major threats to natural conservation involve the
destruction and fragmentation of native ecosystems, mostly due to seasonal
mass tourism and its by-products (e.g., garbage dumping and alien introduction:
Briasoulis, 2003; Vogiatzakis et al., 2008; Affre et al., 2010) and to improper
afforestation activities.

A deeper insight into the effects of human pressure
In the following paragraphs, we analyse the complex interaction between

botanical heritage, past and present human pressure, and conservation
priorities.

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