The aim of this report was to investigate whether the management of protected forests cause increased risk of infestation by the European spruce bark beetle (Ips typographus) in production forests, and whether the risk of infestation in production forests is greater in the vicinity of protected forests. The survey was conducted by using GIS-data covering suspected attacks and forests that are susceptible to infestations. The proportion of infested forests in three different buffer zones located around the protected areas were compared. The results show no evidence suggesting that protected areas serve as a hatchery for spruce bark beetles and no increased risk of infestations in the vicinity of protected forests were detected.

In many natural forests, forest managers fell and debark spruces (Picea abies) colonised by theEuropean spruce bark beetle (Ips typographus) to prevent the beetle from spreading to other tree stands. The aim of this study was to examine how this method affects the biodiversity of other saproxylic beetle species. Eclector traps were installed on debarked and non-debarked dead spruces of four different ages in four nature reserves to compare the richness and composition of saproxylic beetles. The results indicated that a significantly higher number of species and individuals emerged from standing dead trees with bark compared to debarked logs. The highest emergence of species and individuals occurred in one-year-old standing trees with bark. There was a significant interaction between the type and the age of wood, suggesting thatthe richness declined with the aging of wood with bark, while it remained constantly low in debarked logs. The species composition varied greatly between standing trees with bark and debarked logs, as well as between standing trees with bark of different ages. This study demonstrated that debarking spruces as a pest control method reduces the diversity of nontarget saproxylic beetle species. Potential reasons behind that could be the hardening and drying of consumable parts of the wood, rendering it inhabitable for many saproxylic organisms, as well as the presence of the European spruce bark beetle itself, which is associated with many other species.

Norway spruce (Picea abies) is a vital tree species in Sweden's extensive forested landscape. However, the planting of spruce beyond its natural range has made it vulnerable to pests like the spruce bark beetle (Ips typographus), which has caused substantial damage to Swedish forests. With the effects of global warming and climate change becoming increasingly apparent, understanding the factors influencing spruce mortality is crucial for effective forest management. This study aimed to investigate the impact of soil moisture and tree size on the susceptibility of Norway spruce to spruce bark beetle attacks. Using a combination of an Artificial Intelligence (AI) program detecting dead spruce trees and soil moisture data from the Swedish University of Agricultural Sciences (SLU), areas in Stockholm County with dead spruce trees were identified. Spatial analysis using Geographic Information System (GIS) tools and a field survey were conducted to evaluate the hypotheses: H1: Spruce mortality will be higher in areas occurring within mesic soil moisture class (1) than within mesic-moist soil moisture class (2) and moist-wet soil moisture class (3). H2: Large diameter spruce trees will have a higher mortality rate from spruce bark beetle than smaller diameter trees. H3: Spruce mortality will be higher in areas located inside nature reserves. The results confirmed that spruce mortality was higher in areas with dryer soil, Additionally, larger diameter spruce trees exhibited higher mortality rates from spruce bark beetle attacks than smaller trees. Contrary to the initial hypothesis, the study did not find a higher spruce mortality rate in areas located outside nature reserves. The conclusion of this study is that both tree size and soil moisture affect the Norway spruce’s ability to defend itself from spruce bark beetle attacks, but it does not confirm that spruce trees inside nature reserves have a greater mortality rate due to bark beetle attacks than the surrounding areas. The study has contributed to a better understanding of how spruce bark beetles choose trees. It has also provided more knowledge and validation of the Swedish Forest Agency AI program, which is trained to find dead spruce trees. The fact that this is a working tool opens a lot of possibilities for further use. The knowledge of soil moisture’s effect on spruce survival will also help forest managers make better choices when selecting areas for planting spruce. This will also benefit both the forest owners economically and help suppress the spread of spruce bark beetle. / Gran (Picea abies) är en viktig trädart i Sveriges omfattande skogslandskap. Dock har plantering av gran utanför dess naturliga utbredningsområde gjort den sårbar för skadedjur så som Granbarkborre (Ips typographus), vilket har orsakat betydande skador på svenska skogar. Med effekterna av klimatförändringar är det alltmer viktigt att förstå vilka faktorer som påverkar granens sårbarhet mot granbarkborren för en effektiv skogsförvaltning. Denna studie syftade till att undersöka påverkan av markfuktighet och trädstorlek. Genom att använda en kombination av ett artificiellt intelligensprogram (AI) som identifierar döda granar och markfuktighetsdata från Sveriges lantbruksuniversitet (SLU), identifierades områden i Stockholms län där det fanns döda granar. En spatial analys med hjälp av geografiska informationssystem (GIS) och en fältundersökning genomfördes för att utvärdera hypoteserna: H1: Granens dödlighet kommer att vara högre i områden med torr-frisk mark (1) jämfört med områden med frisk-fuktig markfuktighet (2) och fuktig-våt markfuktighet (3). H2: Granar med större diameter kommer att ha en högre dödlighetsgrad från granbarkborrsangrepp än granar med mindre diameter. H3: Granens dödlighet kommer att vara högre i områden i naturreservat än utanför. Resultaten bekräftade att granens dödlighet var högre i torrare områden. Dessutom uppvisade granar med större diameter högre dödlighetsgrad från garnbarkborreangrepp än mindre träd. Resultatet kunde inte bekräfta hypotes H3, man fann inte en högre dödlighetsgrad hos gran i områden inom naturreservat. Slutsatsen av denna studie är att både trädstorlek och markfuktighet påverkar granens förmåga att försvara sig mot granbarkborreangrepp, men den bekräftar inte att naturreservat har en påverkan på granens dödlighet till följd av granbarkborreangrepp än omgivande områden. Studien har bidragit till en bättre förståelse för hur granbarkborren väljer granar. Den har också tillfört mer kunskap och bekräftat att Skogsstyrelsens AI-program hittar döda granar. Att AI-programmet är ett fungerande verktyg öppnar upp många möjligheter för framtida användningsområden. Kunskapen om markfuktighetens effekt på granens överlevnad kommer också att kunna hjälpa skogsförvaltare att fatta bättre beslut vid val av områden för plantering av gran. Detta kommer att gynna både skogsägarna ekonomiskt och bidra till att minska antalet granbarkborreangrepp.