Nutrient inputs in litterfall and rainwater fluxes in 27-year old red, black and white spruce plantations in Central Ontario, Canada

This study was undertaken to examine some nutrient cycling pathways in plantations of several species within the genus Picea. As no such studies currently exist, species within this genera in eastern North America are often managed inappropriately in a collective fashion, when in fact major differences in nutrient demand and utilization may occur. Nutrient inputs in throughfall, stemflow and litterfall fluxes were investigated in white spruce ( Picea glauca (Moench.) Voss), red spruce ( Picea rubens Sarg.) and black spruce ( Picea mariana (Mill.) BSP) plantations growing on the same site. The study was carried out in 1992 and 1993 in a replicated, 26–27-year old planting in the Swan Lake Forest Research Reserve, Algonquin Provincial Park, Ontario. Annual litterfall fluxes of N, P, K, Ca and Mg were always greatest in white spruce when compared to the other two spruces. For example, the N flux was estimated to be 2.72 g m −2 for white spruce as compared to 1.39 g m −2 and 1.62 g m −2 for red and black spruce, respectively. While this pattern held for N, P and K in the total throughfall and stemflow flux (e.g. for N: 0.28 g m −2 for white as opposed to 0.19 g m −2 (red) and 0.17 g m −2 (black)), there were no differences in the Ca and Mg fluxes. Incident precipitation was enriched in total N, organic N, NH 4 +–N and K beneath white spruce as compared to red or black spruce, but not in Ca, Mg or NO 3 −–N. The canopies of all three species decreased P loadings to the forest floor. Elemental returns of N, P, Ca and Mg in the annual litterfall flux exceeded returns in the combined water fluxes by 4–16 times, depending upon tree species and nutrient. For K, water fluxes for all three species were marginally higher than those in litterfall. The results indicate the need for species-specific information on the interaction of crown structure and tree morphology on nutrient deposition and re-cycling in plantation systems.