Page 30 - PastaLaMantia_2013

The vascular flora of the satellite islands of Sicily

Re-think afforestation, now or never
Six of eleven of the terrestrial habitats that have disappeared on at least one of
the circum-Sicilian islands correspond to woody plant communities, and these
are 5210 (arborescent matorral with Juniperus spp.), 91AA* (Eastern white
oak woods), 9260 (Castanea sativa woods), 9320 (Olea and Ceratonia forests),
9340 (Quercus ilex and Quercus rotundifolia forests), and 9540 (Mediterranean
pine forests with endemic Mesogean pines) (Table 4). Moreover, the above-
mentioned studies on succession outlined that the speed and the path of
secondary succession mostly depend on 1) the structure of landscape patchwork
(i.e., the average distance between patches requiring propagules and mature
patches where those propagules are produced), 2) the disturbance regime (i.e.,
frequency and intensity), and 3) climate and microclimate. Because of different
combinations of these three parameters, succession at Lampedusa will require
more than one century in order to reach a mature woody community, while a
total recovery of the evergreen maquis at Pantelleria will occur within 50 years.
Thus, afforestation practices could be recommended not only where
pre-forest and forest ecosystems are critically endangered or have already
disappeared but also to facilitate the natural progressive succession processes
under severe bioclimatic stress. For this purpose, old-fashioned practices like
subsoiling and planting pure, dense, and monospecific stands should not be
used because they have been proven to be ineffective in re-activating local
ecosystem functioning. Such practices should be replaced by more sustainable
and low-impact ones, like the regular sowing of a mixture of seeds of native
shrubs that are able to enhance or restore local facilitation mechanisms (Pasta
et al., 2012a).
As already emphasized by Pasta and La Mantia (2009), Sicilian forest
ecosystems play an important role in protecting many endemic, rare, or
endangered plants. This is true also in the case of satellite islands, where semi-
natural woodlands also deserve special attention. For example, the remnant
Castanea sativa orchards at Pantelleria and in the Aeolian Archipelago are not
only a living monument of past agro-forestry activities but also continue to
be the unique habitat for the rare, threatened, and/or protected plant species
listed in Tables 6–7. As a consequence, any future project aimed at managing
or even restoring Sicilian microinsular pre-forest and forest ecosystems must
be planned carefully to avoid abrupt changes of abiotic factors (e.g., light and
humidity) or biotic factors (e.g., herb-layer coverage) that could menace those
plants that require protection.

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