Where are the forests with highest biomass in Sweden located?

Abstract: Identification of high-biomass sites can lead to further studies on their ecology with the purpose to inform climate change mitigation decisions or give an indication to which sites need stronger protection. The purpose of this study was to, via a remotely sensed data set of tree biomass, identify the locations with the highest biomass in Sweden. As biomass varies across the extent of a stand or forest, the identification was done over four different sizes: 100 ha (1000 m x 1000 m), 25 ha (500 m x 500 m), 6,25 ha (250 m x 250 m) and 1 ha (100 m x 100 m). Additionally, the distribution of the sites across geographical regions and forest management intensities was investigated. It was found that the forests with the highest biomass nationwide were the nemoral nature reserve Osbecks bokskogar (for 100 ha, 220 t/ha), the south boreal non-protected island Upprannsön (for 25 and 6.25 ha, 251 and 277 t/ha respectively) as well as the north boreal managed forest Västansjö (1 ha, 376 t/ha). Most of the top sites for the largest size were in primary- and protected forests as these have relatively consistent biomass across their whole extent. Protected forests differ from production forests which instead consist of individual stands of varying, sometimes low, biomass which means that they were not well represented among the top sites for the larger sizes. At a smaller size, 1 ha, production forests made up a larger fraction of the highest biomass stands as individual stands late in their rotation cycle in some cases contained very high biomass. Most of the top values were found in the southern- to middle regions in Sweden, with very few being located in the northernmost areas.