The effects of nitrogen and warming on inorganic nitrogen pool and production rates in arctic and boreal ecosystems: inorganic nitrogen transformation during a 3-month laboratory incubation

We incubated (2006) northern Alaskan soils (boreal and tundra) at two temperatures (5 degC and 15 degC) and two levels of nitrogen addition (with and without) to directly test for nitrogen limitation of inorganic nitrogen production rate and explore the interaction between temperature and nitrogen limitation. Over the 3-month laboratory incubation, we measured initial extratable inorganic nitrogen and inorganic nitrogen production rates from organic and mineral soils from four different ecosystem types (boreal burned, boreal unburned, moist acidic, moist non-acidic). To charactarize the soils, we also measured total C, total N, microbial biomass, isotopes values (delta 13, delta14), total free amino acid, and total soluble protein.