NUTRIENT DYNAMICS IN DECOMPOSING LEAF LITTER OF 4 TREE SPECIES ON A SANDY SOIL IN NORTHWESTERN WISCONSIN

The dynamics of 12 elements in decomposing leaf litter of jack pine (Pinus banksiana Lamb.), paper birch (Betula papyrifera Marsh.), trembling aspen (Populus tremuloides Michx.), and northern pin oak (Quercus ellipsoidalis E.J. Hill) were examined on a Typic Udipsamment (Orthic Regosol) in northwestern Wisconsin. Whereas the concentrations and absolute amounts of N, Ca, S, Zn, Mn, Fe, Cu, and Al generally increased after 1 year of decomposition, the levels of P, K, Mg, and B in decomposing leaf litter decreased. Two-way analysis of variance tests revealed significant differences in dry matter and concentrations and contents of most elements as a function of species and time elapsed. Macronutrients commonly were released from decomposing leaf litter in the following order (fastest to slowest): aspen > oak = birch > pine. The changes in N, P, Ca, and S in decomposing leaf litter generally followed the three-phase process described for N by other investigators. A cubic function described the initial-loss, accumulation, and final-release phases of these nutrients in decomposing leaf litter.