Published: 10.06.2015 | Author: Bjørn Moe
A BOG IN GOOD CONDITION
The unusual bog landscape, with enormous peat deposits surrounded by steep mountainsides, makes Reppadalen in Arna an exciting, but little visited tour destination for most of Bergen's inhabitants. Those who live in Arna, however, know to make the most of its beautiful natural splendour.
There are few bog areas in Bergen that are both large and intact. There are some, but usually at a high elevation. One of the largest is at Reppadalen, at 400 metres elevation. This bog area is tucked up in the side of Arnadalen. It is about a kilometre long and ends in a glacial cirque. Here, in the transition area between forest and mountain, it is an easily accessible hiking area with forested wood roads and trails up from Arnatveit. Previously, there was mountain farming up here. Today, there are only sheep that graze around the abandoned farm.
There are few species in the vegetation, but the area is large and varied. The bog is especially moist on the large flat area innermost in the valley. A little tarn is becoming overgrown with beaked sedge. In the western part of the valley one finds bogs containing peat-mounds (known as "palsa"). These mounds have to manage on the nutrients they get from above, from rainwater. The plants that do best under such harsh conditions are Scotch heather, cross-leaved heath, cloudberry and hare's-tail cottongrass. The mounds can be quite high. Then, they can easily become dry and tend to collapse partially together, such that the breaks between them appear as dark brown zones with little or no vegetation. The bogs grow slowly upwards, so that over the course of thousands of years they have created up to several metres thickness of peat layers in the valley.
In Reppadalen there are also bogs on the slopes, especially where the ground faces north. In order for a bog to form on a slope, there must be a low rate of evaporation and a high annual rainfall. This kind of bog forms much shallower peat and is found only in smaller areas between grazing land and birch forest.
- Kofoed, J. -E. 1979. Myrundersøkingar i Hordaland i samband med den norske myrreservatplanene, supplerande undersøkingar. Det kgl. norske videnskab. selsk., museet. Univ. i Trondheim. Rapport 1979–5.