Wildfire is a natural disturbance in boreal forests, but its impact can be devastating [1, 2]. Fires lead to habitat loss for many species, and severely affect trees, ground vegetation, and soil physiochemistry, all of which impact the soil microbial community that drive carbon and nutrient cycling [3]. Fire suppression policies have historically decreased fire frequency in Sweden leading to the accumulation of fire fuels [4]. In 2018, extremely hot and dry weather sparked the conditions for the worst fire season in Sweden's modern history where approximately 25 000 ha of forest and almost 3 million m3 of wood were destroyed [5]. Current predictions indicate that changes in temperature and precipitation patterns will likely increase the frequency and severity of fire [6]. While ground fires combust vegetation, litter and soil organic matter, higher severity fires, such as crown fires, lead to tree death and stand replacement. Fire severity, its effects on the ecosystem, and post-fire management influence the ecological succession of soil microbial communities [7]. Ectomycorrhizal fungi (EMF), which establish symbiosis with plants, are essential for plant growth through the provision of water and nutrients, and forest soils that favor EMF are better at storing carbon [8]. After a severe fire with tree death, EMF fungi can take 15 to 18 years to re-establish completely [3, 9], strongly delaying forest recovery. Less EMF will hamper tree growth and consequently the absence of roots will facilitate soil erosion, leading to decreased soil carbon stocks and potentially negatively affecting water quality[10, 11]. For these reasons, it is vital to investigate the impact of fire severity as well as salvage logging on EMF diversity and functions. With this valuable information we will improve the understanding of the effects of fire on forest recovery and ecosystem services, allowing for an evidence based post-fire management that can be used to mitigate climate change. I will compare EMF diversity and abundance in four sites located in Ljusdal: unburnt, low severity with live trees, high severity burn with dead trees and high severity burn followed by salvage-logging. Meshbags, one of the few tools available to quantify EMF growth [12], will be installed in all sites allowing for EMF ingrowth during the plant growing season. By quantifying ergosterol [13] from meshbags I will estimate EMF biomass and thus their ability to store carbon in the forest floor. The EMF biomass accumulated in the meshbags will be used to extract DNA [12] with a DNeasy Plant Pro kit (Qiagen, Germany). The DNA will be amplified and sequenced with Illumina sequencing at BGI Genomics (Hong-Kong). These data will provide a description of the EMF community composition. By combining that with data on biomass and abundance of each EMF member, I will provide novel insights on which keystone EMF species to target with post-fire management and infer how functions have been affected