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The beech in Norway – a late immigrant or an early introduction?

Date: 2011.12.29

The beech (Fagus sylvatica) in Norway established in 500 and 1000 AD and is mainly distributed in two distinct areas – in Vestfold, eastern Norway, and at Seim in western Norway north of Bergen. As these populations are isolated from the beech elsewhere in Scandinavia, it has been speculated whether the beech spread by natural means, or if it was actually the first tree species to be introduced by man in Norway.

The world’s northernmost beech population is located at Seim north of Bergen. Photo: Tor Myking, Forest and landscape

Establishment slightly before or under the Viking age implies that the beech was the last tree species to arrive in Norway. The extensive isolation of the beech at Seim is a strong indication that it was intentionally introduced. The beech in Vestfold, however, is more enigmatic. Located closer to the beech populations in southern Sweden (Båhuslen and Skåne) and Jutland, natural spread by birds is conceivable. Jays are known to be important vectors for spread of beech after the last ice age.

To trace the origin of the Norwegian beech and clarify whether it was spread by birds or man, we collected beech populations from Seim and Vestfold, and in areas where Norway had close relations during the Viking time, i.e. Denmark and England. It is usually assumed that the beech at Seim origins from the beech in Vestfold, the nearest population. The beech material was analysed by genetic markers (ISSR). To investigate the mode of spread we compared the genetic variation in the populations. Spread by birds over long distances would probably cause a substantial loss of genetic variation due to the limited number of seeds that the jays can carry.

The distribution of beech in northern Europe. The dots north of the distribution line indicate scattered small populations.

The results showed a clear genetic relationship between the populations in Denmark and Vestfold. Actually, it was as strong as between the individual populations in Vestfold. There was also a genetic similarity between populations in Denmark and Seim, but somewhat weaker. Interestingly, there was no kinship between the populations in Vestfold and Seim. The English populations could not be related to any of the other populations. Thus, the results suggest that the beech in Denmark is a direct source for the beech in both in Vestfold and Seim.

The genetic variation was generally lower in the Norwegian populations than in the English and Danish populations. Still, the difference is less than what we would assume if the Norwegian populations where originally founded by relatively few airborne seeds. Accordingly, the Norwegian beech populations where possibly established by a larger amount of seeds, suggesting that humans were involved in the spread.

Intentional introduction could have been due to the beech seeds which were valuable fodder for pigs, and even humans if food supply was scarce. Beech also has a very dense and technically valuable wood, and several items of beech wood have been found in Osebergskipet, a Viking ship from AD 834 excavated in Vestfold, as well as in several other excavations in the Oslo fjord area.

The open symbols show the sampled populations. The results indicate that Denmark is the origin of the beech both at Seim and in Vestfold. This contradicts the previous assumption that the beech at Seim descended from Vestfold.

Possibly, people in the days of self-support brought whatever could make life easier and better, and beech might have been regarded a natural choice. We should not forget that the Vikings were skilled sailors. Ocean crossing of Skagerrak took place already from 4000 BP, and was common from about 900 AD onwards. The effective transportation on sea implied that certain cultural impulses actually reached Norway before Denmark. The sea was the highway of the time.

In conclusion, the results indicate that the beech in Norway was an early introduction rather than a late immigrant, and that the source is Denmark. A new tree species that could serve both as food and construction wood was possibly highly valued in a community where most efforts were invested in survival.

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