The interaction of human beings with wild reindeer and the animals' grazing and trampling behaviour has shaped the northern ecosystems since the last ice age (Suominen and Olofsson:235). Nomadic Sami herding emerged in the 17th century (Nakkalajarvi:40), and was based on pasture rotation from the coastal summer lands of Norway to inland areas of Finland-Sweden or, after Finland was ceded to Russia by Sweden in 1809, Finnish Russia (the Grand Duchy of Finland under the Russian Empire). In difficult winters, marked by hard snow, thick snow or icy ground, reindeer exhibited an emerging characteristic of seeking forage outside of the normal pasture rotation. People used to say: "After a good lemming year there will be a bad year for reindeer "(M1-M13, F1-2). The reindeer "broke loose" and went into forests with a rich availability of arboreal lichens or onto fell slopes with "wind-whipped snow" (Gibson; Vuojala-Magga et al.; Turunen and Vuojala-Magga). Animal behaviour like this can be seen as a temporal act of habitat selection resulting in an enlargement of the animals' niche. However, harsh conditions increased winter mortality and/or reduced the reproductive rate of the weakest reindeer; in early winter these were the young rutted bulls, thereafter the one-year-old calves and, in late winter, the pregnant females.
In 1852 the border between Norway and Finland was closed and the human-reindeer migration routes from the coast to the forest areas were shut down (Itkonen). Closing the border was a lengthy process. The official reasons given for doing so were that high numbers of reindeer migrated from Norway to Finland, damaging crops and lichen pastures, and that forest reindeer owned by Inari Sami herders were joining the herds going back to Norway (Itkonen; Enbuske; Jouste). As a result, many families moved from Norway to Sweden with their herds to continue the winter migration to Finland, as the border between Sweden and Finland was still open. The niche based on pasture rotation was re-arranged among the Sami families, who had used lands in Norway and Finnish Russia. However, grazing pressure increased in some areas in northern Sweden, which led to a deterioration of relations between Sweden and Norway. Eventually, in 1883, a law regulating human-reindeer movement between the countries was passed, and by 1889 the border between Sweden and Finland was also closed (Itkonen; Nakkalajarvi: 42-54; Jouste; Koch and Miggelbrink).
In spite of the closure of the border, the nomadic Sami of Utsjoki herded their reindeer to Norway until the 1860s (Itkonen). An old herder recalls the old pasture rotations: During those years when there were no fences separating co-operatives, reindeer foraged in their natural ways - there were rutting places, calving places and winter areas. And once the sun began to rise, the reindeer rose up on the mountains; people moved with the reindeer, followed them and remained with the herd. In summer time reindeer grazed in the coastal area of Varangerbotten (in Norway) and later (winter) went all the way to the Saariselka forest area (in Finnish Russia). The main thing was not to mix up different herds" (M1). Over time pasture rotation diminished and herders ended up with smaller pasture regions in Utsjoki, in Finnish Russia (Itkonen). This meant that reindeer were herded nearly 12 months per year on the same pasture lands. The carrying capacity of the land was exceeded (Jouste:47). Between 1878 and 1882 there was a dramatic decrease in the reindeer population, from 31,683 to 19,633 animals (Jouste:43). In 1898, reindeer herding in Finnish Russia was organized in a system of geographically defined co-operatives and the old nomadic routes were discontinued by the end of the century (Kortesalmi).
The border closures caused drastic changes within the herding communities. The decrease in pasture land reduced the availability of winter forage. The Russian Czar's act mandating sustainable use of reindeer pastures brought out the characteristics of reindeer in a new light; grazing and trampling negatively affected niche construction and reindeer became key constructors of the niche for the time being. Neither animals nor herders had possibilities for adaptation, but rather were forced to seek new land in the more southern, forested areas of Finnish Russia; they sought to enlarge their niche, because there was still room for new people and herds farther south (Jouste).
Although there have been massive moth outbreaks throughout the past centuries, hardly any old documents on the outbreaks exist from Finnish Russia. There were shifts in the elevation of the birch tree line already during the 19th and early 20th century in Abisko, Sweden. There are clear indications that the combination of mass moth outbreaks and reindeer browsing has destroyed mountain birch forests since the beginning of the Holocene (Holtmeier and Broll). In the years 1902-1903, moth outbreaks caused severe damage to the fell vegetation. Documents from the 1920s indicate that Sami herders gradually abandoned campsites in the affected areas (Emanuelson; Cairns and Moen; Van Bogaert et al.:918-917).