Characterization of nutrient regimes in some continental subalpine boreal forest soils

To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segregated by direct soil nutrient measures, we collected samples of forest floor and mineral soil (0 to 30 cm) from a wide range of forest sites throughout the Engelmann Spruce — Subalpine Fir (ESSF) zone of British Columbia. The samples were analyzed for acidity, total C, total N, mineralizable N, and extractable Ca, Mg, K, P, and SO4-S. The study sites were stratified according to an a priori field classification (SNRs) and an a posteriori classification derived from quantitative classification (groups) using all direct measures of nutrients as discriminating variables. The two classification methods had 72% agreement. Regardless of the classification, nitrogen-related variables (C:N ratio, total N, and mineralizable N) in the mineral soil segregated best among SNRs or groups indicating the presence of a steep, N-driven regional soil nutrient gradient. Multiple regression models using SNRs, groups, or direct mea...