Decomposition of leaf litter in an Appalachian forest: effects of leaf species, aspect, slope position and time

Leaf decomposition was studied using leaves of three species (yellow-poplar, red maple, and chestnut oak). Litterbags containing 10 g of leaves were placed on a northeast-facing slope and a southwest-facing slope and at three slope positions (upper, middle, and lower) on each aspect. Bags were initially placed in January and samples were removed to determine mass loss beginning in April, then at 2 month intervals until December. The main effects (aspect, species, slope position and time of removal) were all statistically significant. Yellow-poplar and red maple litter decomposed much faster than did chestnut oak, and leaves placed on north-facing slopes decomposed faster than those on south-facing slopes. Generally, leaves placed at the middle slope position decomposed slower than at those at either the upper or lower positions. We examined the microarthropods in leaf litter during the growing season and found that Oribatei and Collembola dominated the populations present. They were generally more abundant in leaves on north-facing slopes, and numbers of microarthropods generally increased throughout the year. Chemical analysis of decomposing leaf litter revealed that nitrogen and phosphorus contents of leaves were relatively stable over time. Sodium dropped quickly at first, then stabilized. Potassium and magnesium decreased with the time whereas calcium increased in the leaves of some species and decreased in others.