Page 1 - CELESTI-GRAPOW

P. 1

Plant Biosystems, 2016
Vol. 150, No. 5, 1119–1133, http://dx.doi.org/10.1080/11263504.2016.1218974

Plant invasions on small Mediterranean islands: An overview

1
1
1
2
2
L. CELESTI-GRAPOW , L. BASSI , G. BRUNDU , I. CAMARDA , E. CARLI ,
6
5
4
3
6
G. D’AURIA , E. DEL GUACCHIO , G. DOMINA , G. FERRETTI , B. FOGGI ,
L. LAZZARO , P. MAZZOLA , S. PECCENINI , F. PRETTO , A. STINCA , & C. BLASI 1
6
9
7
5
8
1 Department of Environmental Biology, Sapienza University, Rome, Italy; Department of Agriculture, University of Sassari,
2
Sassari, Italy; Plant Pathology Laboratory, UOD Fitosanitario Regionale, Naples, Italy; Department of Biological Science,
3
4
University of Naples Federico II, Naples, Italy; Department of Agricultural and Forestry Sciences, University of Palermo,
5
Palermo, Italy; Department of Biology, University of Florence, Florence, Italy; Department of Earth, Environment and Life
7
6
Sciences, University of Genoa, Genoa, Italy; IAFES Division, Euro-Mediterranean Center on Climate Change, Viterbo, Italy
8
and Department of Agriculture, University of Naples Federico II, Naples, Italy
9
Abstract
Biological invasions have become one of the main drivers of habitat degradation and a leading cause of biodiversity loss
in island ecosystems worldwide. The spread of invasive species poses a particular environmental threat on the islands of
the Mediterranean Basin, which are hot spots of biodiversity and contain rare habitats and endemic species, especially on
small islands, which are highly vulnerable to biodiversity loss. Following a recent survey, in this paper we aim to provide
an overview of the present-day non-native vascular flora of small Mediterranean islands based on a sample of 37 islands
located in the middle of the Mediterranean Sea, off the coast of Italy. By comparing the current data with those gathered
during a previous survey conducted in the same study area, we also aim to highlight the main changes that have occurred
in non-native plant species diversity, establishment and distribution in recent years and to present a first general overview
of the most prominent plant taxa in the island’s introduced flora, focusing on those most responsible for these changes and
those that pose the greatest environmental threats. We recorded 203 non-native plant species, 147 of which have established
on at least one of the islands investigated. Overall, we detected a sharp increase in the number of species, in their levels of
establishment and in the extent of their distribution within the study area in recent years. This may be explained by the
intensification of research on plant invasions, as well as to new introduction, escape, establishment and invasion events on
the islands in recent decades. The most remarkable plants detected include acacias and succulents, two groups that appear to
be emerging very rapidly and to be posing new threats to the conservation of the islands’ natural environment, especially the
genus Carpobrotus, whose spread into natural habitats containing rare and endemic taxa is seriously threatening biodiversity
on both a local and global scale. On the whole, our results show that the plant invasion phenomenon in the study area
has in recent years intensified considerably. As this process seems likely to continue, we should expect more establishment
events in the future and the further spread of species that are already present. This is of particular conservation concern
on the islands investigated in this survey, which are rich in endemisms, but have been facing deep socio-economic and
environmental transformations in these last decades as a consequence of the abandonment of traditional management
practices and the development of tourism. Our study thus confirms that plant invasions on Mediterranean islands are
a serious environmental problem that threatens biodiversity conservation not only in the Mediterranean biogeographic
region, but also on the global scale, and highlights the need to further increase efforts aimed at preventing, controlling or
mitigating the effects of plant invasions in island ecosystems.
Keywords: Acacia, biological invasions, Cactaceae, Carpobrotus, eradication, established alien species, nature conservation,
Italy, succulence, threats to global biodiversity
Introduction
related to the invasions of vascular plants is the threat
The invasive spread of species introduced outside they pose to the conservation of natural resources
their native geographic ranges as a result of human (Hulme et al. 2013). The uncontrolled expansion
activity has become a major environmental problem of a small number of plant species often results in a
in many parts of the world (Simberloff et al. 2013; markedly altered environment and strongly reduced
van Kleunen et al. 2015). One of the main concerns biodiversity (Powell et al. 2011; Jeschke et al. 2014).

1 2 3 4 5 6