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  Role of forest research in minimizing impacts of climate change to boreal forests

Minimizing the impacts of climate change on boreal forest ecosystems

Due to greenhouse gas emissions the temperature of the earth’s atmosphere is projected to rise by about 6°C by 2100. There is an urgent need to cut emissions so that the world’s climate will not become unbearable.

The targets set by the European Council to reduce emissions by at least 20% by 2020 is a good step ahead. The readiness to commit to this goal should not be influenced by the economic depression.
It appears that temperatures will rise most in the Nordic region. Shorter, milder and more humid winters will influence soil freezing, snow cover, soil stability and erosion.

“Studies in growth chambers show that the growth and photosynthesis of forest trees in northern Europe is in fact promoted by elevated CO2 concentrations and elevated temperature. However, we still don’t know if forest trees are genetically capable of adapting to those favorable growing conditions.” says Dr. Elina Vapaavuori, who leads Metla’s research program Functioning of forest ecosystems and use of forest resources in changing climate .

In boreal forest ecosystems, climate change is expected to increase the risk of damage caused by storms, flooding, drought, nutrient deficiency, insects and fungi.

The frequency and intensity of storms have increased lately, and this trend is predicted to continue in northern Europe, particularly during the winter. As an example, in January 2005 a storm with winds gusting up to 165 km/h hit Sweden; the storm felled more than 70 million m3 of wood in a few hours. This corresponds to one year’s annual cut in Sweden.

“Heavy rains and floods will probably cause problems for tree root systems and also tree canopy as air humidity increases. In summertime, long periods of hot weather and drought are expected. Although plausible scenarios show an increase in summer precipitation in northern Europe, much depends also on how the water comes”, says Dr. Vapaavuori.

Heavy rainstorms would cause many problems, whereas more evenly distributed rains might even make growing conditions better in some areas.

Some damage caused by forest pathogens and insects to individual trees is normal and considered acceptable and even desirable in forest ecosystems, but if biotic agents succeed in spreading over overly large areas, forest damage will occur. The prevalence of damaging agents and the resultant damages vary, depending on pest populations and weather conditions.

It is predicted that some forest pathogens and insects benefit from climate change. This includes the most destructive disease of conifers in the boreal forest ecosystems – root-rot – which is caused by the fungus Heterobasidion parviporum, and the European pine sawfly Neodiprion sertifer.

Also some pests not normally causing damage may benefit from rising temperatures. A massive outbreak of the mountain pine beetle (Dendroctonus ponderosae) has occurred in British Columbia, Canada. It has destroyed over 10 million ha of forests.

Pine beetle usually causes only limited outbreaks in these ecosystems, but a series of hot summers followed by mild winters has allowed the beetle population to increase.

“Certainly the forest sector has to be alert to the possibility of such outbreaks, and more attention has to be paid to forest health than previously. Two questions must be asked: In this climatic situation where ecosystems are changing, what elements of the forest ecosystem are important to conserve? Also, what factors are important for mitigation of the climate change?” asks Dr. Vapaavuori.

The role of forest research

In 2007 Metla started a research program of more than 20 researchers to study the functioning of forest ecosystems and the use of forest resources in changing climate.

With the help of forest research we can minimize the impacts of climate change on boreal forest ecosystems and adapt forestry to changing conditions. One important research question is what species and provenances should be used in forest regeneration to improve forest growth and the stress tolerance of trees.

Furthermore, research can provide the information to develop policy measures to promote the right types of forest management. It is also important to critically evaluate the different competing needs of forest resources for timber production, bioenergy and carbon storage, while at the same time considering the recreational need for the welfare of society.

The transfer of knowledge on appropriate forest management operations to forest owners is another challenge for forest research. Wise forest management operations can reduce the risk of insect or fungi outbreaks in forest ecosystems, or risks of storm in large areas.

If forests have to be cut too early because of a pest outbreak, the income of forest owners is reduced and the potential of forests to carbon sequestration is lost. For maximum climate change mitigation, forests should be kept in such a condition that CO2 is fixed as efficiently as possible.

“We do not know if our current management recommendations are suitable for the future. The current management practices have to be revised for forests in different growing phases. There are several important questions to be addressed, such as what problems will we probably meet, how to minimize them, and how to make the most of the CO2-absorbing potential of forests, while not forgetting to ask what is good for forest owners.” ML

Further information:

Metla´s research program Functioning of forest ecosystems and use of forest resources in changing climate