Seasonal Variation in Soil Nutrients Under Six Rocky Mountain Vegetation Types

Abstract

AbstractSoils under vegetation types dominated by Festuca idahoensis, Artemisia tridentata, Populus tremuloides, Pseudotsuga menziesii, and Abies lasiocarpa were sampled at monthly intervals during 1974 and 1975 to determine the magnitude of seasonal variation in nutrient availability. Results may be summarized by expressing minimal values observed in 1974 as a percentage of maximum values: nitrate 27%, ammonium 30%, phosphorus 45%, potassium 65%, calcium 77%, magnesium 82%, sodium 60%, and organic matter 80%. Nutrients were most available in the early fall (September — October) and least available at midwinter (January — April). Rates of change in nutrient availability were smallest in winter and spring. Seasonal variation in Abies forests was notably less than in other vegetation types.