Materials and methods
Study area
The study was carried out along the Swedish-Norwegian border
(60°45’-61°35’N, 11°55’ – 12°55’E) in the Norwegian municipalities of
Trysil, Elverum, Våler and Åsnes and the Swedish counties of Värmland
and Dalarna (Fig. 1). The topography of the study area exhibits a
gradient from higher altitudes in the north to lower altitudes in the
south, with approximate elevations ranging from 900 to 400 meters above
sea level (masl) (Copernicus Land Monitoring, 2018). The northern part
of the study area has a continental climate and is dominated by bare
mountains, marsh complexes and deep valleys with dense old-growth
forests and vast heathlands (Jansson and Antonson 2011). The forest is
primarily composed of Scots pine (Pinus sylvestris ), Norway
spruce (Picea abies ) and birch (Betula spp.) (Jansson and
Antonson 2011). The mean daily temperature in January and July are
–10° C and 15° C, respectively. The ground is typically covered with
snow from late October to early May, and the vegetation period spans
approximately 140-170 days
(www.smhi.se;www.senorge.no). Annual
precipitation in the area ranges from approximately 600 to 1000 mm. The
southern part of the study area is mostly dominated by Scots pine,
Norway spruce and birch forests, which are extensively managed for
timber and pulp (Yrjölä 2002; Lundmark et al., 2013). The mean
temperature in January and July is similar to the northern parts, but
snow mostly covers the ground between December and March. Due to
intensive silviculture practices, the study area features an extensive
network of forest gravel roads. Additionally, the presence of national
and regional roads contributes to a mean road density of 0.84 km/km2
within the study area.