FOREST FLOOR AND SOIL NUTRIENT STATUS UNDER NORWAY SPRUCE AND RED PINE IN A PLANTATION IN SOUTHERN QUEBEC

The influence of 40 years of red pine and Norway spruce growth on forest floor and soil nutrient status was examined in a well-replicated series of plantation blocks established on abandoned agricultural land. Concentrations of N, P, K and Ca, and mass of organic matter and all nutrients in the forest floor were higher under spruce than under pine. In the mineral soil, concentrations of exchangeable K and Ca were higher under spruce whereas Mg, extractable P and mineralizable N did not differ between the species. Forest floor pH was higher under spruce but mineral soil pH did not differ between the species. The soil characteristics reflected litter chemistry of the two species. Relative to pine, spruce foliage litter was consistently higher in nutrient concentration and had lower acidity and higher ash bases. The results are inconsistent with the reputation of Norway spruce as a species that strongly acidifies soils, an observation that may be the result of elevated levels of Ca and K in our soils relative to those in other studies where acidification has been observed. This research demonstrates that soil fertility can be altered significantly by tree species effects over the period of a single rotation.