Vulnerabilities - Alps

Forests make up more than 40% of the Austrian total territory. During the last few decades different air pollutants (especially ozone) have lead to significant damage to the mountain protection forests. Thus, the northern Alps reveal the highest percentage of damaged trees (54%) due to the loss of needles and leaves. In Tyrol 42% are damaged on the average, while Tyrolean production forests reveal a damage rate of only 30%. The average damage rate for the entire Austrian forest amounts to 33% with approximately 7% of the trees damaged more seriously (1).

Indirect effects relate to losses caused by fire, insects and diseases. The indirect effects depend on the influence of climate on the disturbance agents themselves. Warming in winter, e.g., may allow destructive insects and pathogenic fungi to survive at higher latitudes and altitudes than at present, enabling subtropical or warm-temperate pests and pathogens to invade vegetation from which they are now excluded (2).

These negative effects can be of the same magnitude or even higher than the positive impacts as CO2 fertilizing and the lengthening of the growing season. Additional risk factors are the possibility of an increase of extreme events (e. g. storms) (3).

In most areas, precipitation is not the limiting factor. However, at the eastern and southeastern edge of the Alps (border of the former Slovenia) the mean annual precipitation is low (about 400-500 mm), so even a small decrease in precipitation or changes in precipitation patterns may have severe impacts on the stress scenario of the remaining forests (4).

Increased wind damages, especially in northern and western Europe, may more frequently result in an imbalance in orderly harvesting procedures with increased costs and disturb timber markets with an imbalance between the supply and demand of timber (4).

Vulnerabilities - Overview

The increased vulnerability of forests (and people) with respect to climate change refers to several impacts (26,32):

• Forest cover: conversion of forests to non-woody energy plantations; accelerated deforestation and forest degradation; increased use of wood for domestic energy.
• Biodiversity: alteration of plant and animal distributions; loss of biodiversity; habitat invasions by non-native species; alteration of pollination systems; changes in plant dispersal and regeneration.
• Productivity: changes in forest growth and ecosystem biomass; changes in species/site relations; changes in ecosystem nitrogen dynamics.
• Health: increased mortality due to climate stresses; decreased health and vitality of forest ecosystems due to the cumulative impacts of multiple stressors; deteriorating health of forest-dependent peoples.
• Soils and water: changes in the seasonality and intensity of precipitation, altering the flow regimes of streams; changes in the salinity of coastal forest ecosystems; increased probability of severe droughts; increased terrain instability and soil erosion due to increased precipitation and melting of permafrost; more/earlier snow melt resulting in changes in the timing of peak flow and volume in streams. The capacity of the forest ecosystem to purify water is an important service, obviating the cost of expensive filtration plants.
• Carbon cycles: alteration of forest sinks and increased CO2 emissions from forested ecosystems due to changes in forest growth and productivity.
• Tangible benefits of forests for people: changes in tree cover; changes in socio-economic resilience; changes in availability of specific forest products (timber, non-timber wood products and fuel wood, wild foods, medicines, and other non-wood forest products).
• Intangible services provided by forests: changes in the incidence of conflicts between humans and wildlife; changes in the livelihoods of forest-dependent peoples (also a tangible benefit); changes in socio-economic resilience; changes in the cultural, religious and spiritual values associated with particular forests.

Productivity

Increasing CO2 concentration can affect tree growth through increased photosynthetic rates and through improved water-use efficiency. There will be complex interactions, however: forest growth rates may well be increased in some cases by rising levels of atmospheric CO2, but rising temperatures, higher evaporation rates and lower rainfall may lower growth rates in other cases (17).

Non-timber products

Increasingly there are concerns about the productivity of non-timber products such as medicines and foods. Relatively little information is available in the scientific literature about the sustainable management of such products, and even less is known about their vulnerability to climate change (26).

Vulnerabilities - Eastern Alps

The Eastern Alps, and Mountain regions in general, provide a wide range of ecosystem services: production of timber and biomass for energy, shelter for settlements and infrastructure against gravitational natural hazards like snow avalanches, rock fall and landslides, nature, recreation, the provisioning of drinking water and the dampening of runoff peaks for hydropower production, carbon sequestration, and non-wood forest products, such as mushrooms and berries (35).

The impact of climate change between now and 2100 on two of these ecosystem functions, timber production and protection against landslides and avalanche release, has been evaluated for the Province of Vorarlberg in Austria, close to the Swiss border. This was done for two scenarios of climate change (compared with the reference period 1960–2000): the B1 and A1B scenarios, with annual mean temperature increases by +2.6 °C and +4 °C, respectively, until the end of the century. The impact of disturbances due to bark beetles and browsing by ungulate game species were taken into account (36).

The evaluation shows moderate impacts of a changing climate on European mountain forests during the first half of the twenty-first century, in accordance with many other studies (e.g. 37). After 2050, however, climate change impacts are more distinct: potential timber production volumes increase, but bark beetle damage increases as well, even overtaking timber volume increment (36). An increase in bark beetle damage affects forest productivity, increases cost for salvage operations, and reduces timber quality. Moreover, it also adversely affects the protective function of forests against snow avalanches, rock fall and landslides by creating gaps in the forests. Under scenarios of mean annual temperature increase up to +4 °C until the end of the century, a distinct intensification of the bark beetle disturbance regime was found to be a major driver (36).

The results of the current contribution cannot be extrapolated to the entire European Alps, however: the forest structure of the study area, for instance, is an uneven-aged featuring rather large and old trees, whereas far stretches of the northern Alps are characterized by even-aged stands (36). 

Vulnerabilities – Temperate forests in Europe

Present situation

In parts of Europe with temperate forests, annual mean temperatures are below 17°C but above 6°C, and annual precipitation is at least 500 mm and there is a markedly cool winter period (6). Temperate forests are dominated by broad-leaf species with smaller amounts of evergreen broad-leaf and needle-leaf species (7). Common species include the oaks, eucalypts, acacias, beeches, pines, and birches.

Many of the major factors that influence these forests are due to human activities, including land-use and landscape fragmentation, pollution, soil nutrients and chemistry, fire suppression, alteration to herbivore populations, species loss, alien invasive species, and now climate change (8).

Forest productivity has been increasing in western Europe (9). This is thought to be from increasing CO2 in the atmosphere (10), anthropogenic nitrogen deposition (11), warming temperatures (12), and associated longer growing seasons (13).

For Norway spruce in the Northern Limestone Alps (Germany and Austria), neither growth suppression at the lower elevation sites nor growth increase at higher elevation sites was observed in a dataset covering more than 150 years (until 2003), despite a sharp temperature increase of ~1°C since the 1990s (34). According to the authors, these findings reveal the ability of mountain forests to adapt to an unprecedented temperature shift, suggesting that adaptation to forthcoming climate changes might not require a shift in tree species composition in the Northern Limestone Alps (34).

Trends

Most models predict continuing trends of modestly increasing forest productivity in Western Europe over this century (14). Projections for the time near the end of the next century generally suggest decreasing growth and a reduction in primary productivity enhancement as temperatures warm, CO2 saturation is reached for photosynthetic enhancement, and reduced summer precipitation all interact to decrease temperate zone primary productivity (15). The projected increased occurrence of pests, particularly in drought-stressed regions, also contributes to decreased long-term primary productivity in some regions of temperate forests  (16).

Sensitivity to increasing air pollution loads, particularly nitrogen deposition and tropospheric ozone, will impact large areas of the northern temperate forest over the next century. In the temperate domain, air pollution is expected to interact with climate change; while the fertilization effects from nitrogen deposition are still highly uncertain, pollutants such as ozone are known to diminish primary productivity (17).

Migration

The ranges of northern temperate forests are predicted to extend into the boreal forest range in the north and upward on mountains (18). The distribution of temperate broadleaved tree species is typically limited by low winter temperatures (19). Since the latter are projected to rise more rapidly than summer temperatures in Europe and North America, temperate broad-leaved tree species may profit and invade currently boreal areas more rapidly than other temperate species.

Carbon sinks/sources

Temperate forest regions in the highly productive forests of western Europe (20) are known to be robust carbon sinks, although increased temperature may reduce this effect through loss of carbon from soils (21). Weaker carbon sinks or even carbon losses are seen for temperate forests in areas prone to periodic drought, such as southern Europe (22).

Models suggest that the greatest climate change threat to temperate forest ecosystems is reduced summer precipitation, leading to increased frequency and severity of drought (23). This will probably be most prominent in temperate forest regions that have already been characterized as prone to drought stress, such as southern Europe. Drought-stricken forests are also more susceptible to opportunistic pests and fire (24). Together, these related effects can potentially change large areas of temperate forest ecosystems from carbon sinks to sources.

Benefits

Globally, based on both satellite and ground-based data, climatic changes seemed to have a generally positive impact on forest productivity since the middle of the 20th century, when water was not limiting (33).

Timber production in Europe

Climate change will probably increase timber production and reduce prices for wood products in Europe. For 2000–2050 a change of timber production in Europe is expected of -4 to +5%. For 2050–2100 an increase is expected of +2 to +13% (25).

Adaptation strategies

Stand management has to be close to old growth or natural stands because it increases biodiversity, soil fertility, improves the resilience of stands and insures that stands are less susceptible to physical and/or biotic disturbances (4).

The genetic variability of most common tree species is probably large enough to accommodate the mean changes in temperature and precipitation. Problems may be encountered with the changes in the frequency and amplitude of extreme events such as drought, wind and spring and summer frost. Currently there is a tendency to prefer native tree species and a more nature-oriented approach in management. Simulation studies in northeastern Germany suggest that there is a considerable potential to improve climatic adaptation of forests by means of adaptive forest management strategies (5).

Adaptation strategies - Forest management measures in general

Near-nature forest management and a move away from monocultures toward mixed forest types, in terms of both species and age classes, are advocated. In addition, natural or imitated natural regeneration is indicated as a method of maintaining genetic diversity, and subsequently reducing vulnerability. For management against extreme disturbances, improvements in fire detection and suppression techniques are recommended, as well as methods for combating pests and diseases. It is reported that through stricter quarantine and sanitary management, the impact of insects and diseases can be minimized. The establishment of migration corridors between forest reserves may aid in the autonomous colonization and migration of species in response to climate change (30).

Adaptive management

The terms adaptation and adaptive management are often incorrectly used interchangeably. The former involves making adjustments in response to or in anticipation of climate change whereas the latter describes a management system that may be considered, in itself, to be an adaptation tactic (27). Adaptive management is a systematic process for continually improving management policies and practices by learning from the outcomes of operational programmes (28). It involves recognizing uncertainty and establishing methodologies to test hypotheses concerning those uncertainties; it uses management as a tool not only to change the system but to learn about the system (29).

Both the climate and forest ecosystems are constantly changing, and managers will need to adapt their strategies as the climate evolves over the long term. An option that might be appropriate today given expected changes over the next 20 years may no longer be appropriate in 20 years’ time. This will require a continuous programme of actions, monitoring and evaluation – the adaptive management approach described above (26).

There is a widespread assumption that the forest currently at a site is adapted to the current conditions, but this ignores the extent to which the climate has changed over the past 200–300 years, and the lag effects that occur in forests. As a result, replacement of a forest by one of the same composition may no longer be a suitable strategy (26).

Adaptation to climate change has started to be incorporated into all levels of governance, from forest management to international forest policy. Often these policies are not adopted solely in response to climate, and may occur in the absence of knowledge about longer-term climate change. They often serve more than one purpose, including food and fuel provision, shelter and minimizing erosion, as well as adapting to changing climatic conditions (30).

Socio-economic and political conditions have significant influences on vulnerability and adaptive capacity. Climate change projections are perceived by many forest managers as too uncertain to support long-term and potentially costly decisions that may be difficult to reverse. Similarly, uncertainty over future policy developments may also constrain action. Finance is a further barrier to implementing adaptation actions in the forest sector (31).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Austria.

1. BMLF (1996), in: Federal Ministry of Agriculture, Forestry, Environment and Water Management (2010)
2. Dobson and Carper (1992); Schopf (1997), in: Federal Ministry of Agriculture, Forestry, Environment and Water Management (2010)
3. Federal Ministry of Agriculture, Forestry, Environment and Water Management (2010)
4. Kellomäki et al. (2000)
5. Lindner (2000), in: Kellomäki et al. (2000)
6. Walter (1979), in: Fischlin (ed.) (2009)
7. Melillo et al. (1993), in: Fischlin (ed.) (2009)
8. Reich and Frelich (2002), in: Fischlin (ed.) (2009)
9. Carrer and Urbinati (2006), in: Fischlin (ed.) (2009)
10. Field et al. (2007b), in: Fischlin (ed.) (2009)
11. Hyvönen et al. (2007); Magnani et al. (2007), both in: Fischlin (ed.) (2009)
12. Marshall et al. (2008), in: Fischlin (ed.) (2009)
13. Chmielewski and Rötzer (2001); Parmesan (2006), both in: Fischlin (ed.) (2009)
14. Alcamo et al. (2007); Field et al. (2007b); Alo and Wang (2008), all in: Fischlin (ed.) (2009)
15. Lucht et al. (2006); Scholze et al. (2006); Alo and Wang (2008), all in: Fischlin (ed.) (2009)
16. Williams et al. (2000); Williams and Liebhold (2002); Logan and Powell (2001); Tran et al. (2007); Friedenberg et al. (2008), all in: Fischlin (ed.) (2009)
17. Fischlin (ed.) (2009)
18. Iverson and Prasad (2001); Ohlemüller et al. (2006); Fischlin et al. (2007); Golubyatnikov and Denisenko (2007), all in: Fischlin (ed.) (2009)
19. Perry et al. (2008), in: Fischlin (ed.) (2009)
20. Liski et al. (2002), in: Fischlin (ed.) (2009)
21. Piao et al. (2008), in: Fischlin (ed.) (2009)
22. Morales et al. (2007), in: Fischlin (ed.) (2009)
23. Christensen et al. (2007); Fischlin et al. (2007); Meehl et al. (2007); Schneider et al. (2007), all in: Fischlin (ed.) (2009)
24. Hanson and Weltzin (2000), in: Fischlin (ed.) (2009)
25. Karjalainen et al. (2003); Nabuurs et al. (2002); Perez-Garcia et al. (2002); Sohngen et al. (2001), in: Osman-Elasha and Parrotta (2009)
26. Innes (ed.) (2009)
27. Ogden and Innes (2007), in: Innes (ed.) (2009)
28. BCMOF (2006a), in: Innes (ed.) (2009)
29. Holling (1978); Lee (1993, 2001), all in: Innes (ed.) (2009)
30. Roberts (ed.) (2009)
31. Keskitalo (2008), in: Roberts (ed.) (2009)
32. Kirilenko and Sedjo (2007)
33. Boisvenue et al. (2006)
34. Hartl-Meier et al. (2014)
35. Malin and Maier (2007); Hollaus et al. (2007); Maroschek et al. (2009); Lindner et al. (2010), all in: Maroschek et al. (2015)
36. Maroschek et al. (2015)
37. Seidl et al. (2011); Elkin et al. (2013), both in: Maroschek et al. (2015)