Nutrient content of throughfall in paper birch and red pine stands in northern Minnesota

Gross precipitation and throughfall in the open and under forest vegetation were sampled and analyzed for total content of N, P, K, Ca, and Mg. The results indicate the importance of the tree canopy, Pinusresinosa Ait. and Betulapapyrifera Marsh., in modifying the nutrient content of precipitation passing through the overstory vegetation. Contributions of nutrients to throughfall by the understory vegetation, mainly Coryluscornuta Marsh., were related to the areal coverage of the hazel as well as to high levels of nutrients in the hazel foliage. Gross precipitation annually added relatively small amounts of major nutrients to forest ecosystems in northern Minnesota.