Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
4.4.5 Forest composition and distribution
Key messages
• Range shifts in forest tree species due to climate change have been observed towards higher altitudes and latitudes.
These changes considerably affect the forest structure and the functioning of forest ecosystems and their services.
• Future climate change and increasing CO 2 concentrations are expected to affect site suitability, productivity, species
composition and biodiversity. In general, forest growth is projected to increase in northern Europe and to decrease in
southern Europe, but with substantial regional variation. Cold-adapted coniferous tree species are projected to lose large
fractions of their ranges to more drought-adapted broadleaf species.
• The projected changes will have an impact on the goods and services that forests provide. For example, the value of forest
land in Europe is projected to decrease between 14 and 50 % during the 21st century.
Relevance
Forests and other wooded land cover approximately
182 million ha (1.82 million km 2 ) in the EU-28 region;
this area has increased by more than 4 million ha in
the last 15 years (UNECE and FAO, 2015). Forests and
woodlands are key providers of timber, wood fuel and
energy, water, food, medicines, recreation and other
ecosystem services. Forests are habitats for a large
fraction of biological diversity. The pervasive influence
of climate on forests is obvious. Climate affects the
composition, structure, growth, health and dynamics
of forest ecosystems. At the same time, forests also
influence local, regional and even global climate through
carbon removal from the atmosphere, absorption or
reflection of solar radiation (albedo), cooling through
evapotranspiration, and the production of cloud-forming
aerosols (Arneth et al., 2010; Pan et al., 2011; Pielke et al.,
2011). Changes in temperature and the availability of
water will affect the relative health and productivity of
different species in complex ways, thereby influencing
the range of most species and forest composition.
These shifts may have severe ecological and economic
consequences (Hanewinkel et al., 2012). Generally,
European forests have been becoming older and they
have been close to carbon saturation point (Nabuurs
et al., 2013). More information on the state and trends of
European forest ecosystems can be found in EEA (2016).
Short- and long-term managing strategies are needed
to mitigate and adapt to the impacts of climate change
on European forests and forestry. Strategies should
focus on enhancing forest ecosystems' resistance
and resilience, and on addressing potential limits to
carbon accumulation (Kolström et al., 2011; EC, 2013a).
Maintaining and restoring biodiversity in forests
promotes their resilience and therefore can buffer
climate change impacts (Thompson et al., 2009). Specific
strategies may include planting species that are better
adapted to warm conditions and more resistant to
pests and diseases, landscape planning and forest
management oriented towards decreasing fuel loads in
fire-prone areas, the promotion of carbon storage, the
consideration of renewable energy and the introduction
of payments for services from forests (Fares et al.,
2015). Nevertheless, introduced alien species may
have negative effects on the native flora, e.g. through
competition with native species or by modifying the
physical condition of the sites (Kjær et al., 2014).
Past trends
Trees are slow-migrating species. Range expansion
occurs primarily into newly suitable habitats at their
(generally northern) latitudinal or (upper) altitudinal limit.
Range contraction occurs primarily at the rear edge,
which is often the most southern or the lowest lying
part of their distribution range. These areas can become
unsuitable for tree species as a result of direct effects
(e.g. drought) or indirect effects (e.g. drought‐induced
pests or diseases) of climate change. In France, the
altitudinal distribution of 171 forest plant species along
the elevation range 0–2 600 m was studied using a
101-year data record starting in 1905. Climate warming
has resulted in a significant upwards shift in species
optimum elevation averaging 29 m per decade, but
with a wide range from + 238 to – 171 m per decade
(Lenoir et al., 2008). Land-use changes are the most likely
explanation of the observed significant downwards shifts
in some regions (Lenoir et al., 2010). In the Montseny
mountain range in north-east Spain, the altitude range
of beech extended by about 70 m upwards according to
different data sources from the 1940s to 2001 (Penuelas
and Boada, 2003). A study comparing data from the
1990s with data from the 2000s in the Spanish Pyrenees
and the Iberian Peninsula found an average optimum
elevation shift of 31 m upwards per decade for five
tree species, ranging between − 34 and + 181 m per
174 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report