The importance of forestry

Of the total land area over the period 2004-2008 70% was forest land, 12% was barren land and 5% was other wooded land. Forest is an important natural resource that provides the basis for biobased energy supply. Over the past 50 years agricultural land has been successively converted to other land use, principally forest land, and this has contributed to reduced emissions from agriculture and increased carbon sequestration in forest biomass (1).

Increased demand from the forest industry resulted in a significant increase in forest felling over the period 1990-2007, and timber use reached a new record level in 2004-2007. Despite increased felling, the total timber stock has increased from around 2.8 billion m3 to 3.3 billion m3 since 1990 (1).

Benefits from climate change

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 (25).

The generally warmer climate, a longer vegetation season and an increased carbon dioxide level in the atmosphere will result in greater growth. New tree species and different types may lead to even higher production Calculations show that the rate of growth of pine, spruce and birch will gradually increase so that by the end of the century it is 20−40% higher than today (2).

The increase of forest growth is expected to be greatest in the north, relatively speaking. In the south, drier summers will mean that an increase in growth as regards spruce will change to a decrease during the latter part of the century. A warmer climate also provides the potential to cultivate new tree species for timber production whose northerly limit currently runs through either the most southerly parts of our country or even further south. Among the valuable broadleaved trees, it is considered that oak and beech could expand northwards (2).

The tree line is predicted to shift upward by several hundred metres (3). There is evidence that this process has already begun in Scandinavia (4). The northward expansion of forests is projected to reduce current tundra areas under some scenarios. There are no obvious climate adaptation options for either tundra or alpine vegetation (5).

The consequences for Sweden’s forests and forestry will be significant. Increased growth will result in greater timber production, although increased frequency and extent of damage primarily from insects, fungi and storms, as well as wetter forest land, can entail considerable costs. Sweden’s forests and forestry are the foundation for the Swedish forest industry, one of the most important businesses in the country. In 2003, the forest industry’s production value amounted to SEK 181 billion, which constituted 13% of the manufacturing sector’s total processing value. The forest industries and forestry’s combined processing value constituted 3% of GNP (6). For the period 2010–2100, increased earnings of forestry are estimated between SEK 300–600 billion (2).

Paper and cardboard production are the most important in terms of overall processing value, although the production of timber for wooden goods is responsible for 2/3 of the timber’s value (7). Pine and spruce are the most important tree species in Swedish forestry and the forest industry. In recent decades, biofuels from the forest have once again become important, along with timber for wooden goods, paper and packaging. Out of Sweden’s total land area of 41 million hectares, 23 million hectares are productive forest land (2).

Future forest policy and the consequent management should also balance the increasing capacity of forests to sequestrate carbon and the potentials to increase the supply of  timber into the inner markets of Europe, while sustaining wood-using industries. The possible shift of tree species composition towards increasing dominance of hardwoods may affect the wood-processing techniques and this should be considered in future investments (12).

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% (23).

Vulnerabilities - Overview

The increased vulnerability of forests (and people) with respect to climate change refers to several impacts (14,24):

• 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.

The warmer climate will make the forests more prone to fire, fungal and insect attack, for example by spruce bark beetle. The increased presence of pests is expected to increase costs in forestry. Costs will also arise due to difficulties in felling, transporting timber to main roads and on to industry due to wetter winters and less frost (2,10).

Damage resulting from storms, droughts and fire is also expected to increase. In historic terms, storms have been responsible for the greatest economic damage in forestry. Hurricane Gudrun in 2005 brought down or damaged around 75 million cubic metres standing volume, which is equivalent to almost a year’s felling in Sweden. The total cost to forestry was estimated at between SEK 11−12 billion (8).

On the whole, a warmer climate will probably result in denser stocks of and higher grazing pressure from herbivorous game. Pressure from predators and hunting are decisive as regards the size of the game stocks, however. The extent of the damage is also probably dependent on forest management (2).

For the forests in northern Europe, the combination of raised mean temperature and a higher frequency of extreme events will have negative effects that could ultimately be of greater importance than the positive outcomes of a warmer climate. The boreal forests, for example, may be severely affected by summer dry spells and droughts, making trees more susceptible to frost damage, windthrow, storms and attacks by pests and diseases (9).

In Europe, the forested areas are the main source of groundwater, and they absorb precipitation and reduce the risk of excess surface flow and floods and erosion. In this respect, the groundwater resources in northern and western Europe are in no danger as is the case in central and southern Europe. The reduction of forest cover may increase surface flow and floods. In northern Europe, the increasing precipitation may also increase the risk of floods even though the forest cover buffers watersheds (12).

Wood production

In general, management has a greater influence on wood production in Europe than climate or land-use change. Forest management is influenced more strongly by actions outside the forest sector, such as trade and policies, than from within (11).

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 (12).

The shortening of thermal winters deteriorates the preconditions of timber harvesting and transportation of timber in forest truck roads, since the lack of ground frost weakens ground-bearing capacity (43)

Vulnerabilities - 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 (14).

Vulnerabilities - peatlands

Peatlands cover a large portion of the land area in the Nordic countries. In Finland about 30% of the land area is covered with peat of varying thickness, in Sweden 25%, in Iceland 10% and in Norway 8%. Parts of these peatlands are being used for agriculture, often as grassland for cattle and milk production. In Finland and Sweden, for instance, organic agricultural soils cover 10% and 7% of the agricultural land area, respectively (26).

The development of new drainage techniques at the beginning of the 20th century has accelerated the exploitation of peatland area and altered patterns of use. In the Nordic countries between 3% and 40% of the original peatland area has been drained for agricultural purposes. In some regions, e.g. in Finland, more than 50% of the peatlands are drained for forestry and only 3% for agriculture. Land drainage in all the Nordic countries was largely a government driven policy to mitigate severe socio-economic risks related to emigration to USA, food security, unemployment and poverty (27).

Drainage for agriculture leads to land subsidence

Drained organic soils differ significantly from mineral soils as they subside over a relatively short time period due to compaction, shrinkage, erosion and oxidation. Cultivation in Nordic conditions leads to subsidence rates that can vary from 0.5 cm/year on fields with pasture to 2.5 cm/year on fields with row crops (28). This subsidence leads to loss of organic matter, leaching of nutrients, mineralization of carbon and nitrogen and therefore emission of greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O).

Agricultural peatlands require repeated lowering of drainage as subsidence alters the effectiveness of the original drainage system with reduced bearing capacity and lower yields. Ultimately, long-term agricultural usage of peatland depends on the possibilities to redrain the peat, and the quality of underlying substrates and its suitability for long-term agriculture (26).

Drained peatlands emit greenhouse gases

Organic soils are responsible for a significant portion of the anthropogenic CO2 and N2O emissions (29). N2O emission is particularly relevant since N2O is a 300 times more effective greenhouse gas than CO2. Drainage of peatlands changes the hydrology and microbiological processes of the peat and therefore impacts gas exchange from the peat dramatically. Greenhouse gases emissions associated with peat extraction, peatland forestry and agriculture have to be accounted for in national inventories on total emissions of greenhouse gases.

And draining peatlands has several other negative effects

Peatlands are important to mitigate regional flooding since they store water from heavy rainfall. Draining peatlands may therefore negatively impact flood protection. Also, ecosystem processes such as carbon sequestration and biodiversity are disturbed. Due to drainage, water flows more vertically through the topsoil layer leaching out nutrients, dissolved organic carbon, and in some cases metals (30).

Adaptation strategies

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 (13).

Adaptation strategies - Forest management measures in general

The establishment of migration corridors from south to north between fragmented landscapes is reported as a means of aiding the migration of species responding to changed climatic conditions. Changing the species composition to form more stable forests is reported as a management option; an example is changing the species in southern Finland from spruce and pine to birch. In a similar context, Sweden has been working on a breeding programme aimed at developing trees that would be adapted to the projected future climate (15).

To adapt to shorter winter harvesting periods as well as soft soils and roads, new harvesting techniques that better suit new conditions need to be developed. It is also reported that in some regions increasing population levels of large game, in particular moose, will increase the need for game management (15).

Replacement of needle-leaved tree species by broad-leaved species

The boreal forest is experiencing higher rates of warming than any other forested region on the planet (37). Boreal forest fires not only impact greenhouse gas emissions, they also impact human health and safety, damage physical infrastructure, and result in losses of industrial timber. For instance, the 2010 wildfires around Moscow (Russia) were linked to roughly 11,000 deaths through their effect on air pollution (38). The 2016 Fort McMurray fire in Canada resulted in estimated losses of CAD$4.6 billion (36).

In 2015, needle-leaved forests represented 54% of the boreal biome. It is argued that increasing the broad-leaved tree composition is an effective way to adapt to the increased regional fire risk from climate change (36). Because of their higher leaf moisture content and lower flammability, broad-leaved tree species are less likely to burn than needle-leaved (39). Pure broad-leaved stands are about 24 times less likely to burn in a stand-replacing event than pure needle-leaf stands (40). Reducing the risk of wildfires (with regards to both frequency and spread) in boreal biomes through increased broad-leaved tree composition is therefore a means to reduce greenhouse gas emissions (36). Because of the higher year-round albedos of deciduous broad-leaved forests compared
 to evergreen needle-leaved forests, the earth would absorb less solar energy, thus having a cooling effect throughout the boreal zone (41).

A shift from mature needle-leaved to mature broad-leaved forest can reduce the fire risk between three to five times for many boreal forest regions (40). This shift can be made as part of regular management activities in actively managed forests. In southern Canada, for instance, converting just 0.1-0.2% of forested area per year, starting in 2020, may
 even be sufficient to mitigate the expected increase in fires due to climate change, scientists state (42).

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 (17). Adaptive management is a systematic process for continually improving management policies and practices by learning from the outcomes of operational programmes (18). 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 (19).

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 (16).

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 (16).

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 (15).

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 (20).

Adaptive ability

Any community currently dependent on forestry is at risk of destabilization, some more seriously than others. There is likely to be a high level of variation in the ability of forest-dependent communities to adapt to climate change, but there have been relatively few rigorous studies investigating this. One study in northern Europe revealed that the communities in Norrbotten (Sweden), Lappi (Finland) and Arkhangelsk oblast (Russia) differed markedly, primarily because of their varying degrees of dependence on natural resources and their ability to counteract negative effects (21). The greater the diversification of a local economy, the less its vulnerability to climate change is likely to be because of its ‘room for maneuver’ (22).

A country’s ability to adapt to climate change will depend largely on financial, human and institutional capacities; thus the more developed regions may adapt more easily than regions within less developed countries. As the boreal domain consists of comparatively few countries with well- developed economies, there are good grounds for adaptation (15).

Adaptation peatlands: how to stop subsidence and greenhouse gases emissions?

The negative consequences of using peatlands for agriculture as summarized above raise a few pressing questions. Should farming continue on peat soils? Can management choices reduce negative impacts? What alternatives exist and what are their socio-economic and environmental consequences? These questions were addresses in a recent review (26).

Afforestation is not the solution

Some say afforestation of drained peatlands, especially croplands, reduce the overall emissions of greenhouse gases. Indeed, CO2 emission of afforested former croplands can be lower than in arable croplands, although the effect depends strongly on the climatic conditions (31,32). In most cases, however, this is not true for the N2O emissions; these emissions can remain high for decades (33).

One solution: continue cultivation as long as this is profitable

According to the authors of this review there is little or no scientific evidence that changing cultivation methods or growing specific crops can reduce the emission of greenhouse gases. They recommend, therefore, that the sites that are cultivated should continue the cultivation as long as this is profitable. Crops should be managed in such a way as to ensure a maximum return for each CO2 equivalent emitted, they state, and this could be achieved by maintaining biomass levels as high as possible (26).

After cultivation, forestry or biocrops can be an option as an alternative land use, if the soil and drainage is suitable for such vegetation. Forestry or biocrops will not stop CO2 emission from the peatsoils and high N2O emissions may remain, but carbon will be sequestered. Some bioenergy crops can be productive even with a high water table level. For fields too wet to cultivate with agricultural crops, these bioenergy crops could prolong the life of the area as a productive field with the ability to sequester carbon in the biomass. Harvesting these crops on wet soils remains a challenge, however (26).

Another solution: change in land use

Rewetting has been recommended as a practice to protect organic material in former cultivated land from further mineralization by excluding oxygen, and thereby reducing the emission of greenhouse gases (34). It has also been proposed as a method to increase biodiversity. Rewetting must be accompanied by moisture tolerant crops (paludiculture) if one aims to continue agricultural use.

While the goal of rewetting often is to encourage the return of peat forming plants and the ecosystem services they provide such as carbon sequestration, it is not well known if these plants will grow on peat soils that have been altered by the process of drainage and management. Peat extraction followed by rewetting might provide a sustainable option as rewetting is often easier if the nutrient rich topsoil peat is removed, starting the peat accumulation from scratch. Also this provides a way to finance the after-use (26).

In the short term (0-5 years) rewetting can lead to a net increase in the emission of greenhouse gases because stopping drainage may lead to a high but fluctuating water table. A highly fluctuating water table can lead to an increase in CH4 emissions due to submersion of the active rooting layer leading to anoxic mineralization of labile carbon combined with a reduction in CH4 oxidation. In contrast, drained organic soils are only minor sources or even sinks for methane (CH4) (32). Thus it is important to ensure a high and relatively stable water table when drained organic soils are rewetted. Research in the Netherlands has shown that rewetting can restore the carbon sink function of managed peatlands after 15 years (35).

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 Sweden.

1. Ministry of the Environment of Sweden (2009)
2. Swedish Commission on Climate and Vulnerability (2007)
3. Badeck et al. (2001), in: Alcamo et al. (2007)
4. Kullman (2002), in: Alcamo et al. (2007)
5. Alcamo et al. (2007)
6. Statistics Sweden (2006), in: Swedish Commission on Climate and Vulnerability (2007)
7. SOU (2006), in: Swedish Commission on Climate and Vulnerability (2007)
8. Swedish Forest Agency (2006), in: Swedish Commission on Climate and Vulnerability (2007)
9. MICE (2005), in: Behrens et al. (2010)
10. Maracchi et al. (2005)
11. Schröter et al. (2005)
12. Kellomäki et al. (2000)
13. Lindner (2000, in: Kellomäki et al. (2000)
14. Innes (ed.) (2009)
15. Roberts (ed.) (2009)
16. Innes (ed.) (2009)
17. Ogden and Innes (2007), in: Innes (ed.) (2009)
18. BCMOF (2006a), in: Innes (ed.) (2009)
19. Holling (1978); Lee (1993, 2001), all in: Innes (ed.) (2009)
20. Keskitalo (2008), in: Roberts (ed.) (2009)
21. Lundmark et al. 2008, in: Innes (ed.) (2009)
22. Thomas and Twyman (2006), in: Innes (ed.) (2009)
23. Karjalainen et al. (2003); Nabuurs et al. (2002); Perez-Garcia et al. (2002); Sohngen et al. (2001), in: Osman-Elasha and Parrotta (2009)
24. Kirilenko and Sedjo (2007)
25. Boisvenue et al. (2006)
26. Kløve et al. (2017)
27. Runefeldt 2010), in: Kløve et al. (2017)
28. Berglund (1989), in: Kløve et al. (2017)
29. Kasimir-Klemedtsson et al. (1997); Maljanen et al. (2010), both in: Kløve et al. (2017)
30. Saarinen et al. (2013), in: Kløve et al. (2017)
31. Lohila et al. (2011), in: Kløve et al. (2017)
32. Maljanen et al. (2010), in: Kløve et al. (2017)
33. Maljanen et al. (2013), in: Kløve et al. (2017)
34. Smith et al. (2007), in: Kløve et al. (2017)
35. Schrier-Uijl et al. (2014), in: Kløve et al. (2017)
36. Astrup et al. (2018)
37. Gauthier et al. (2015), in: Astrup et al. (2018)
38. Shaposhnikov et al. (2014), in: Astrup et al. (2018)
39. Kasischke et al. (2010), in: Astrup et al. (2018)
40. Bernier et al. (2016), in: Astrup et al. (2018)
41. Bright et al. (2017), in: Astrup et al. (2018)
42. Girardin and  Terrier (2015), in: Astrup et al. (2018)
43. Lehtonen et al. (2019), in: Ruosteenoja et al. (2020)