Peak period of chemical forest fertilisation was short

The felling method employed in Finland is the so-called shortwood logging system . Thanks to this, a larger part of the nutrients contained in the tree remains in the forest than is the case with the tree-with-root system. The part of tree which contains the most nutrients are the green needles. Over 50 percent of the tree's nutrients is contained in the needles and the branches, and the species remaining after final felling are also able to utilise these nutrients. However, the volume of nutrients removed from the forest when felling timber for energy production is about twice as much as in other felling. What is mostly removed from the forest then is nitrogen and phosphorus. The loss of nutrients causes the gravest problems in peatlands, where an extremely high proportion of the nutrients is stored in trees.

One solution to counteract the nutrient loss is fertilisation. Forests are fertilised not only to increase growth, but also to maintain forest health. Fertilisation for growth helps the tree to achieve a good size more rapidly, which will shorten the rotation period. Fertilisation also makes for a denser crown, creating better shade and decreasing the lower branches, which will increase the value of trees. Among all forest improvement measures, fertilisation is clearly the most profitable one.

Chemical forest fertilisation was intensively practised for some years during the 1970s. For environmental reasons, the volumes have been cut down dramatically since. According to forest certification criteria, for instance, forest fertilisation is not allowed on the buffer zones along large or small waterways and water supply areas or in habitats valuable to biodiversity. Soluble fertilisers can only be applied when the ground is not frozen.

9. Volumes of various forest management and improvement measures.

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