Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
Box 4.7
Alien species and climate change: new establishments and new ranges?
It is difficult to predict how global environmental changes such as climate change and biological invasions will affect ecological
systems. Because alien species are mostly opportunistic and generalists, they tend to perform better under a rapidly changing
climate than native species (Hellmann et al., 2008). There is growing concern that invasive alien species may benefit from
climate change and further deterioration in the environment, allowing them to increasingly compete (i.e. increase their
establishment and reproduction rates and their niche breadth) with native species to the latter's disadvantage (Walther
et al., 2009; EEA, 2010; Kleinbauer et al., 2010a; EC, 2014a). Invasive alien species may affect and reduce native biodiversity in
various ways, such as through competition for food and space, predation, disease transfer, and changing habitat structure
and functions. They have negative consequences for their new environment and significant adverse impacts on the goods
and services provided by ecosystems, on the economy and on human health (Millennium Ecosystem Assessment, 2005; Vilà
et al., 2010, 2011; Blackburn et al., 2014; Rabitsch et al., 2016). In response to these increasing pressures, the European Union
has recently adopted a dedicated legislation on invasive alien species (IAS), which aims to reduce the future impacts of alien
species (EU, 2014).
According to the DAISIE ( 64 ) project, there are more than 12 000 non-native species in Europe. An estimated 1 200–1 800 of
them are invasive, and this figure is predicted to rise with the growth in global trade and travel (EC, 2014a). Some recent trends
in alien species introductions to Europe are shown in Figure 4.17. The positive trend in the establishment of new species
indicates that the problem is far from under control, with impacts on biodiversity expected to increase because of the growing
number of species involved, and an increasing vulnerability of ecosystems to invasions, which results from other pressures
such as habitat loss, degradation, fragmentation, overexploitation and climate change. The situation is particularly worrying in
marine and island ecosystems (EEA, 2010).
According to the most recent global analysis of the Red List (IUCN, 2012), IAS constitute a severe threat to various taxonomic
groups of plants and animals. The Red List Index allows the impacts of alien species on the conservation status of native
species to be quantified and indicates the rates at which affected species are moving towards or away from extinction.
Amphibians are known to be particularly affected by IAS and their associated pathogens and diseases. A recent analysis
regarded IAS as a threat to 8 out of the 11 species of amphibians whose Red List status deteriorated between 2004 and 2009
(Rabitsch et al., 2016).
Horticulture and ornamental plant trade are by far the most important pathways of plant introductions to Europe (Keller
et al., 2011). According to the data from EASIN ( 65 ), stowaway (introductions through shipping, aviation and land transport)
is the main pathway for introductions of both terrestrial and aquatic alien species (Katsanevakis et al., 2015). It is difficult to
identify and quantify the role of climate change in species invasions. However, a recent modelling study on '100 of the world's
worst invasive alien species' indicates that, besides habitat characteristics and socio-economic variables such as the distance
to airports, seaports and human population density, climate variables were the main predictors of the distribution of the
studied invasive species (Bellard et al., 2013). Climate change mitigation and adaptation measures may also contribute to the
introduction of new species, for example through cultivation of energy plants and increasing use of dry-adapted species in
forestry (IUCN, 2009).
It is important to note that, while improved border control regulations at Europe's external borders might limit new invasions,
many alien species are already in Europe. Many of these species are currently limited by various environmental factors, but
they might become invasive at some point in the future and no control measures are currently in place to limit invasions from
such species.
An increasing number of warm-adapted alien plant species have recently become established in central Europe, such as
palms, cacti and evergreen tree species (Berger et al., 2007; Walther et al., 2007; Essl and Kobler, 2009). One example is the
windmill palm (Trachycarpus fortunei), which was introduced more than a century ago, but became established in the wild only
recently after the average winter temperature increased and the severity of cold spells decreased (Berger et al., 2007). Alien
plant species have also increased their range by moving uphill (Pauchard et al., 2009). Most alien plant species originate from
warmer regions and will therefore benefit from the projected climate change in Europe (Walther et al., 2009; Schweiger et al.,
2010; Hulme, 2012). For example, future climate will become more suitable for 30 major invasive alien plant species in large
parts of Austria and Germany under different climate change scenarios (Kleinbauer et al., 2010b).
( 64 ) Delivering Alien Invasive Species Inventories for Europe (DAISIE) is a research project funded by the European Commission through the Sixth
Framework Programme, and by the Centre for Ecology and Hydrology (CEH); see http://www.europe-aliens.org.
( 65 ) The European Alien Species Information Network (EASIN) was launched in 2012 by the European Commission to facilitate the exploration
of information on existing alien species and to assist the implementation of European policies on biological invasions; see http://easin.jrc.
ec.europa.eu.
172 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report