By comparison the weather conditions on the coast are wetter, milder and with less variation between cold and heat. The weather and the prevailing climatic conditions are, to a large extent, the factors that decide, the spread of different varieties of plants, for example, beech forests, fir and pine forests, as well as decide what it is possible to plant in such a mountain landscape as in Røros. If the climate changes and gets colder, or drier, or the wind increases, then the forest will be damaged.
Measurements of temperature and precipitation at Røros indicate that January is the coldest month with an average temperature of minus 11.4 degrees and July is the warmest month with an average of 11.5 degrees. Averages hide large variations. In the period between 1957 and 1989 the coldest temperature recorded in January in Røros was minus 45.8 degrees and the warmest January temperature was plus 10.4 degrees. In the summer we can observe similar range with a temperature of 28.6 degrees as a summer temperature during the same period and minus 2 degrees as the coldest summer record. Night frost indicates that we are well up into the highlands. The farmers of Røros have always had to abide by the limitations of nature, and the resources in the uplands have always been a decisive factor in being able to keep domestic animals. In the uplands the grassy meres and bogs were cut to obtain hay. Leaves and twigs were collected as feed, and reindeer moss often became a decisive factor in keeping the animals alive during particularly hard winters. Wheat does not ripen in Røros because the growing period is too short. But wheat was grown and it was used as animal fodder.
The Røros slopes do not receive much precipitation. That means, that in comparison to other parts of the country Røros receives little precipitation in the form of rain or snow. Most of the rainfall is in the period from June to September and the least in the period February to May. Small amounts of precipitation during the winter mean that plants are subject to frost damage. Snow has the property to insulate. If the ground is covered by a thick layer of snow, then plant root systems are better protected against frost damage than those times when there are severe frosts, and little snow. When most of the precipitation falls as rain from June until September and there is little snow in the winter, then there is a real danger of frost damage.
Røros slopes are made up of what we refer to as mountain forest. This means that the forest’s ability to grow is limited by the climatic conditions, particularly temperature and wind. Mountain forest is made up primarily of birch and fir. The climatic conditions determine the tree line, that is the height above sea level that trees can grow. The extent to which forest was allowed to grow on the slopes surrounding Røros has been decided by man from the time the copper works were started. Intensive felling has forced the availability of forest down the slopes to the valleys in lower lying areas such as, Gauldalen and Oesterdalen.
The Røros district together with Norway and the rest of Northern Europe, has throughout history experienced a wide range of climatic conditions, particularly temperature and wind, factors that have lead to the dying out and re-establishment of certain varieties. From the middle of the 1300s and right up to the end of the 1800s we have experienced what has been called the ‘small ice age’. The temperature dropped and low temperatures, particularly in the summer months, made conditions difficult for birch, fir and spruce to survive. Birch is the most sensitive, and it started to die out. Fir takes a longer time to react but eventually the fir forests were also lost. The evidence for this is the remains of large fir trees that we have found well above today’s tree line. The climate started warming up again from the end of the 1800s and continued into the 1900s so the forests have started to recover.
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