To document possible soil nitrogen mosaics before timber harvesting on three boreal forest sites in Alaska, maps of the distribution of understory green (Alnus crispa (Alt.) Pursh) and Sitka alder (A. sitchensis (Reg.) Rydb.) stems were made. Understory alders were regularly distributed throughout the northernmost site (Standard Creek) and very irregularly distributed at the southernmost site (Cooper Landing). No consistent relations existed between alder stem location and total soil nitrogen. In undisturbed forest, soils collected beneath alders tended to have more nitrogen than soils without alder, but after the sites were harvested, soil chemistry differed. To examine the interactions of alder and white spruce (Picea glauca (Moench) Voss) on secondary successional sites, mixed plantations of white spruce and alder were established after each site was harvested. Despite good survival, the planted alder grew poorly. No differences were found between nursery-grown alder seedlings and alder wildlings in either growth or survival. Although fifth-year survival and growth of white spruce were excellent on all sites, they were not related to either the preharvest distribution of naturally occurring alder or to alders planted in the mixed plantations. Locational information and site maps are provided for future evaluation of these plantations.