Based on data collected on forest damage in connection with National Forest Inventories, approximately 50% of Finland’s wood production forest area had suffered damage of varying degrees between 2009 and 2013. The most damage is caused by wind, snow, freezing, and other climatic and weather-related phenomena. The next biggest causes of damage to forests are fungi and deer. However, most damage to forests is of minor significance.

The most notable forest pathogen in Finland is annosum root rot. It causes the forest industry to lose approximately EUR 50 million every year. Climate change threatens to increase the prevalence of root rot. Annosum root rot is common in southern Finland, but its prevalence is also increasing in the north due to climate change. Spruce are more susceptible to root rot than pine.

The biggest threat from non-native species

Climate change and non-native species are new threats facing Finland’s forests. Climate change brings pests from southern Europe to the southern regions of Finland and further and further up north.

Non-native plant diseases and pests are likely to pose one of the biggest threats to the forest industry in the future. They are still rare at the moment, but non-native species are being introduced all the time especially through international plant trade, packaging materials, and people.

A case of ash dieback was recorded in 2007, and needle cast was observed in mountain pine and Scots pine in southern Finland in 2010. Other finds since that time at least include bleeding canker on horse chestnut trees, Phytophthora water mould on alder seedlings, and most recently Asian long-horned beetles, which infest broad-leaved trees, and dieback in the south. The next arrival could be Dutch elm disease.

The Finnish Food Safety Authority is responsible for monitoring and studying the plant diseases covered by plant health legislation. The Natural Resources Institute Finland is responsible for the rest.

Pathogens and the forest industry

It has been suggested that the costs incurred from damage caused by international plant trade should be factored into the prices of plants sold subject to a special licence. This would motivate operators to take better care of their supply chain.

Among forestry operators’ most important means of preventing diseases are choosing the right species of tree from the right source when planting new forests, managing seedling stands according to recommendations, and thinning young forests at the right time. The diversity of species of tree in forests needs to be preserved.

Root rot treatment needs to be introduced across the whole country, with the exception of the northernmost parts of Lapland. Homogeneous stands where there is a high degree of root rot should be replaced by broad-leaved trees in areas where elk are not a problem.

Picture on top of the page: Erkki Oksanen, Luke