Forest litter decomposition in relation to soil nitrogen dynamics and litter quality.

Five adjacent Wisconsin forests were floristically dissimilar, being dominated respectively by sugar maple Acer saccharum, white oak Quercus alba, bigtooth aspen Populus grandidentata, white pine Pinus strobus and hemlock Tsuga canadensis. Nitrogen mineralization rates in the stands ranged from 29-125 kg.ha^-1.yr^-1. Decomposition rates of transplanted sugar maple leaves and red maple Acer rubrum wood were not correlated with N mineralization rates in all 5 stands, indicating that N mineralization rates do not affect initial decomposition rates, but mineralization rates were correlated with decomposition rates of the native dominant foliage litter. Nitrogen first accumulated in all litters, but by the end of 2-yr incubation, N release had begun in all foliage litters. Nitrogen concentrations increased linearly with cumulative mass loss but eventually declined in some foliage litters. Soluble substances and litters relatively rich in solubles disappeared rapidly during early stages of decomposition. Eventually, slowly disappearing acid-soluble and acid-insoluble substances dominated the pattern of mass loss in all litters. -from Authors