NITROGEN MINERALIZATION IN BOREAL FOREST STANDS OF ISLE-ROYALE, NORTHERN MICHIGAN

The correlation of soil temperature and moisture with inorganic N conc entrations and net mineralization beneath major species types in matur e boreal and northern hardwood forests was examined over a two year pe riod. Soils beneath species types where the canopy was dominated by Be tula papyrifera, Picea glauca, Alnus rugosa or, in northern hardwoods, Acer saccharum were studied. Net NO3- mineralization varied by specie s type and net total inorganic nitrogen (N) mineralization varied by m onth and the interaction of species type with month. Soil NO3- concent ration and NO3- mineralization were correlated for spruce, and inverse ly correlated for alder and maple. Soil NH4+ concentration and NH4+ mi neralization were inversely correlated for alder and maple. In laborat ory temperature and moisture treatments of birch, spruce and maple soi ls, NH4+ and total inorganic N-mineralization increased with temperatu re. The response to moisture was most evident for NO3- mineralization in maple soils.