Europes ecological backbone.pdf

Ecosystem services from Europe's mountains
Box 4.3 Impact of climate change on ecosystem services in the Valais, Switzerland (cont.)
Changes to ecosystem services will be driven directly by shifts in forest structure due to the influence of
climate change on growth and competition of forest species, and indirectly through climate-driven shifts in
forest disturbances such as wind throw, fire, and pathogens (Schumacher and Bugmann, 2006). The region's
steep climatic gradients will strongly influence both the direct and indirect effects of climate change. At
lower elevations (< 800 m) the predicted increase in the incidence of droughts will result in species shifts,
e.g. Quercus sp. becoming more important in the forest, with a decrease in the total forest biomass (indicated
with A in Figures 4.2 and 4.3). At intermediate elevations (800–1 400 m), more drought-resistant species
would move to higher elevations, with Picea abies becoming less abundant (indicated with B in Figures 4.2
and 4.3). At the highest elevations (1 400–2 300 m), the increased temperature would allow total forest
biomass to increase, and possibly allow the tree line to move upwards (indicated with C in Figure 4.2 and B in
Figure 4.3).
Climate-induced increases in the frequency and intensity of forest disturbances would have a significant impact
on ecosystem services. Future increases in summer temperature and a possible increase in strong foehn
winds would increase fire risk (Schumacher et al., 2006). While fires, especially larger fires, have historically
been more likely at lower elevations, climate change driven shifts in fire risk would have the largest impact
at intermediate elevations where drought has the largest impact on fire occurrence (Zumbrunnen et al.,
2009). Regional warming and higher summer temperatures would also increase the damage caused by
forest pathogens such as pine wood nematodes, bark beetles and fungal agents (Wermelinger et al., 2008).
A regional dieback of Pinus sylvestris, which began in the 1990s, has been attributed to regional warming that
bolstered pathogen populations while simultaneously making trees more susceptible due to increased drought
stress (Wermelinger et al., 2008; Dobbertin et al., 2004; Dobbertin and Rigling, 2006).
The impact of these direct and indirect climate factors on ecosystem services will be region- and
elevation‐specific. As the valleys are steep and the area is quite heavily populated, protection from
gravitational hazards is a primary ecosystem service provided by forests. Pathogen-induced mortality of
species such as Pinus sylvestris, in combination with the predicted decrease in forest biomass at lower
elevations (indicated with A in Figure 4.3), would lead to a reduction in the protective function of lower
elevation forest. At higher elevations, climate change induced increases in forest biomass will increase the
forests' protective function. Increased temperature may also allow the tree line to shift upwards, providing
further protection; however, this will be influenced more by land-use practices (e.g. the abandonment of
high-elevation pastures) than by direct climate change effects.
The impact of climate change on biodiversity and recreation will similarly be elevation-dependent. At low
elevations, increased drought would lower total forest biomass and shift the species composition towards more
drought-tolerant species. These combined effects will likely decrease both forest diversity and the diversity
of organisms that rely on the forest system. Conversely, at high, and to a lesser degree at intermediate,
elevations, climate change is predicted to increase both forest biomass and tree diversity (indicated with B
in Figure 4.3). The dynamics of how forests change from their current state to one where drought-resistant
species are more dominant will be a key factor that influences ecosystem services in the region.
Source:
Ché Elkin and Harald Bugmann (Department of Environmental Sciences, ETH Zurich, Switzerland).
activities, such as bathing, rafting, canoeing, angling,
hiking, photography or wildlife viewing. In general,
the near-natural and most diverse sections of rivers
in their upper reaches within mountain regions are
more attractive to people due to their high aesthetic
value coupled with a sense of wilderness.
Species diversity in mountains, with many
endemic or charismatic animals and plants (Nagy
et al., 2003: Chapter 8), together with spectacular
landscapes, many with a significant cultural
component deriving from centuries or even
millennia of human use, are of strong aesthetic
value. The associated National Parks, UNESCO
Biosphere Reserves and other protected areas in
mountains (Chapter 9) provide a structured setting
for ecotourism involving the full spectrum of
ecosystem types occurring in these environments
and also have an important role in education and
awareness (e.g. Harmon and Worboys 2004, IUCN
2009). As noted in Box 4.4, they also provide many
other ecosystem services.
Europe's ecological backbone: recognising the true value of our mountains
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