Field of Action Forestry

Stack of wood logsClick to enlarge
Climate change is a threat to forestry production yields.
Source: nena2112/photocase.com

Impacts of Climate Change

Table of Contents

 

Precipitation

In Germany, precipitation in summer will shift to the winter months as a result of climate change: it is expected that the total rainfall during the summer months will reduce by up to 25 per cent by 2050, while it will increase by approximately 25 per cent in autumn and winter.

The changes in total rainfall and the increasingly unequal distribution of rainfall during the different seasons constitute a risk for forest ecosystems, since they disturb the water balance of forest soils . Precipitation surpluses in wet winter months lead to prolonged wet periods. The increased amount of soil water during these periods soaks forest soils. This has negative effects on essential soil functions, such as filtering and storage function of nutrients and pollutants. The economic viability of forest areas can be affected in the long term.

Furthermore, the high degree of humidity also favours the emergence and spread of pests such as fungi. A fungus called “Hymenoscyphus pseudoalbidus”, for example, causes an increased mortality of ash shoots in humid forests. The pest reproduces itself rapidly and spreads easily, while many native tree species grow slowly and can only adapt to climate change over longer periods of time due to their long life cycles. In the long term, these factors could threaten the biological diversity  of forest ecosystems and change the composition of tree species in German forests.

 

Temperature

Apart from increasing average annual temperatures, it is also expected that Germany will encounter more frequent droughts and heat waves, cold winters or drops in temperature in the future. Although the gradual warming leads to longer growing seasons, temperature change and variability can have negative impacts on the regional growing conditions for tree species - especially in conjunction with a modified water supply of forest soils.

Tree species react differently, depending on their respective temperature tolerance and the water availability. Spruce, larch and silver fir, for example, prefer cool, moist locations and are therefore not very drought and heat tolerant. Increasing summer temperatures and drought significantly affect these species in their growth, even death is possible. Increasing temperatures are already affecting the forests in southwest Germany, while forest areas in certain parts of eastern Germany have to deal with low water availability.

Spruce is very susceptible to heat and drought stress due to the fact that it was commonly grown outside of its natural habitat because of its good growth performance. Often it can not withstand the increasing climate change-induced stress under these conditions. In recent years, forestry therefore suffered from particularly high yield losses in spruce groves. Southern and western Germany are particularly affected. In these regions, spruce was often cultivated in non-native habitats. Oak, pine and the non-native Douglas fir are significantly more resistant to temperature changes compared to spruce.

Another risk involved in changes in temperature is the mass distribution  of certain pest insects such as the bark beetle, the pine moth or the May beetle. Due to the higher temperatures, especially the milder winters, they can reproduce quickly. Moreover, their life cycle prolongs and their habitats spread further to the north of Germany. The mass infestation of forests has increased significantly in recent years and caused high economic losses.

During long periods of drought and water shortage also the risk of forest fires increases, especially in pure pine groves. Warmer regions of eastern and southwest Germany, and generally water-deficient areas are particularly vulnerable.

 

Extreme Weather Events

Climate change makes the occurrence of extreme weather events such as droughts, heavy rain or storms more likely. Since the 1990s, forestry has suffered from increasing economic damages caused by wind throws. They can be attributed to more frequent storms with high wind speeds. Compared to slower climate changes, extreme weather events frequently cause serious damage within a short time and they can have serious consequences for humans and the environment. A significantly increased risk of heavy rainfall, falling rocks or floods is expected in the mountain forests of the Alps, for example. For that reason, the importance of forests as protection for infrastructures and settlements may continue to increase.

 

CO2 Fertilisation

Carbon dioxide (CO2) in the air and longer growing seasons can have a positive impact on timber production. A higher concentration of CO2 in the air accelerates plant growth by increasing the rate of photosynthesis. This is the so-called CO2 fertilisation effect. However, this phenomenon that is favourable to the growth of trees is often offset by limiting factors such as water scarcity.

If you are interested in obtaining information about possible adaptation measures in the field of action forestry, please click here.

 

Sources

Adaptation to Climate Change

Technical measures

Technical measures can especially support forest ecosystems in very dry regions where water is insufficiently available during summer months. These measures counteract the increasing lack of water and a drop in the groundwater level. The water balance of soils in alluvial forests can be stabilised by rewetting measures, for example.

Technical measures can also provide protection against forest fires. The forest fire monitoring can be supported by, for example, additional video measures or satellite-based systems.

Ecosystem measures

In forestry, ecosystem adaptation measures are particularly important. As regards measures that focus on the level of ecosystems, strategic planning by politics and the competent forestry institutions is extremely important. In the past, forest ecosystems have constantly adapted to changing environmental conditions, but the extent and the rapid progression of anthropogenic climate change can overstretch the adaptability of long-living tree species. In addition, the adaptability of the different tree species varies. An example is the spruce that is rather common in Germany. It favours cool and moist locations, and is therefore not particularly drought and heat tolerant. Since it is already commonly grown outside of its natural range because of its rapid growth rate, its adaptability will continue to decline in the future.

The conversion of forest monocultures – such as the commonly found spruce or pine monocultures – into structure- and species-rich, multi-layered and thus near-natural mixed forests is a necessary means to ensure the use, protective and recreational functions of the forest in the long term and promote biodiversity. A broader structural and genetic diversity increases the resilience of cultivated forests and thus their adaptability. Resilience means that an ecosystem is capable of withstanding environmental shocks and disturbances such as insect infestations or storms and maintaining its basic organisation and functionality.

Forest conversion measures also contribute to fire protection. In the near future, the risk of forest fires may increase due to longer and more frequent dry and hot periods. Mixed forests are less endangered by forest fires because they have a more humid interior climate. Species-rich mixed forests are also more resistant to insect pests and fungus. Bavaria has already begun with the conversion of forests. As part of the “Forest Conversion Programme Climate Change", 10,000 hectares of coniferous forest in the Bavarian Forest are being converted into mixed forests.

Another possible silvicultural adaptation measure is the introduction of non-native tree species such as the Douglas fir from North America. Compared to many native tree species, this tree is more resistant to temperature changes. Such measures, however, also have to consider nature conservation interests.

The forest conversion allows for a diversification of the timber supply, which also entails economic benefits. In addition, particular mountain forests have the important function of protecting the infrastructure and settlements against rock falls and floods. Forest conversion can also strengthen this function.

In addition, a higher consumption of wood is necessary to contribute to the rejuvenation of the forests. The German forests are increasingly over aged. This leads to a decline in biomass growth and carbon uptake. Rejuvenation on the other hand increases the adaptability and promotes the natural selection of climate-adapted populations.

Legal, political and management measures

As mentioned above, the adaptation of forestry to climate change requires a consistent risk management that deals with damage incidents such as forest fires, storm damage or pest infestation. This is the only way to ensure that risks are identified in time, repelled and dealt with successfully. In addition to short-term crisis management, especially preventive measures such as coordinated water management plans to reduce the risk of fire are important. They should be coordinated at all levels of planning by forest owners, municipalities, landscape associations, forest administration, fire brigade and road construction to incorporate the interests of all stakeholders and to avoid conflicts of use. Projects that develop and test such prevention and management measures are, for example ENFORCHANGE, ForEVAS and RESTER.

The described risk management plans and forest conversion measures require comprehensive knowledge. Against this background, it is necessary to have accurate information as to which tree species are suitable for the respective location when taking future impacts of climate change into account. In addition, it is also necessary to use planning maps or site-mapping to provide information on the prosperity of the tree species under relevant environmental and climate factors. The operation of test areas, regional cultivation recommendations provided by federal and state governments, regular monitoring and research on the use of wood could further improve the information base.

Forest and soil monitoring programmes at European, national or federal state level presently already supply important information. However, there is still enough potential to expand the knowledge base and improve the networking amongst relevant players.

Additionally, with the Forest Climate Fund, the federal government has created a tool that provided seven million euros inter alia for adaptation measures in 2013.

If you are interested in obtaining information about concrete impacts of climate change in the field of action forestry, please click here.

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