AND

Concentrations of N, P, K, Ca, Mg, and N a were measured in rain and snow in the open, and in throughfall and stemflow under black spruce and aspen forests in north-central Minnesota. Concentrations of total P in rain and black spruce throughfall were inversely related to storm size. Annual precipitation nutrient inputs to the forest floor were calculated for each site. In general, nutrient contributions from snow were less than 10 % of the annual nutrient input from precipitation at each site, and differences in snow nutrient input between sites were minimal. Rainfall nutrient input differed significantly between sites. Rain and snow passing through both forest canopies were enriched with nutrients except inorganic nitrogen. Total annual nutrients added to the forest floor under the black spruce stand averaged 1.7 times that added in the open; the annual amount added under the aspen stand averaged 5.2 times that added in the open. VERRY, E. S., et D. R. TIMMONS. 1977. Precipitation nutrients in the open and under two forests in Minnesota. Can. J. For. Res. 7: 112-1 19. On a mesurC les concentrations de N, P, K, Ca, Mg et Na dans la pluie et la neige, 8 dCcouvert, dans les prCcipitations traversant la voilte foliacCe et dans le ruissellement de