Forestry in Sweden depends on successful seedling regeneration. Currently, alternative forestry methods to clearcutting and soil preparation are being discussed, but these established practices both lead to improved seedling survival and growth after planting. Previous studies have identified belowground competition as a possible reason for why seedlings require distance from mature trees and disturbed soil to establish well, but we lack understanding of what mediates this competition. The aim of this study is to elucidate the role of ectomycorrhizal fungi and seedling nitrogen transport dynamics on seedling establishment and growth. 15N-labelled seedlings were planted at different distances from a clearcut edge, with different levels of root-exclusion treatments. After one growing season, seedlings were harvested for growth assessment, isotope measurements, and sequencing. For sequencing, DNA was extracted from seedling roots for ITS amplicon sequencing, which is currently being performed at NGI Stockholm. The aim of analysing this data is to determine fungal community composition differences on seedling roots, at different distances from the mature trees at the clearcut edges, and with different root exclusion levels, in combination with growth measurements and isotope measurements to determine strength and directionality of seedling nitrogen transport processes.