Epsilon Archive for Student Projects

Abstract

The continuity forests of the Swedish boreal landscape have become very sparse due to intensive rotation forestry and human land-use, and the remaining forests are very fragmented. These forests have a high conservational importance as they hold nature values that relies on a long forest continuity. Continuity forests are recognized as essential for biodiversity, both worldwide and in Sweden, and to conserve and strengthen biodiversity it is crucial to map the remaining continuity forests and appoint the appropriate management. In 2017, Metria delivered a dataset that mapped proxy continuity forests (pCF) and provided information about forests that had not been clearcut since the first orthophotos in the 1960s. As they did not have sufficient data, the mapping included large overestimates in some areas, but it is still the best source of data to find continuity forests. I used the pCF-dataset to find core areas (patches) of pCF and combined it with information about high conservation value forest (HCVF) from Metria and Sveaskog. I investigated the share and distribution for different combinations of pCF and HCVF on Sveaskog holdings in 11 regions in northern Sweden. I then investigated how connectivity could be strengthened by developing areas between patches in two selected connectivity study areas. This was done by applying graph theory combined with matrix resistance values. I gave non proxy continuity forests (pCF) categories of forest in this study a higher resistance while prioritized categories such as pCF and HCVF combined were given lower resistance values. I then computed least-cost paths and multiple paths (corridors) between all patches in three different scenarios of land coverage. I repeated this for four different distances in two connectivity study areas and then assessed the importance of paths and patches by applying the connectivity metric index betweenness centrality (BC). The results highlight the Sveaskog ecoparks as connectivity hotspots, with the BC-index revealing the connectivity value of both least-cost paths and patches. In addition, the results also show patches currently isolated and how different dispersal distances affect patch isolation. Most importantly, my results show the relative contribution of patches and identify areas that can be further developed to increase the functional connectivity between patches within a larger landscape. The results are thus relevant both for Sveaskog and for other forest owners.