PARENT SESSION
Oral Session #5: Ecosystem processes: Decomposition and litter. Presiding: K. Lajtha.
Monday, August 6, 2001. 8:00 AM to 12:15 PM. Hall of Ideas E.

Mixed-litter decomposition on calcareous and acidic soils in NW Connecticut.

GARTNER, TRACY¹, CARDON, ZOE¹, ¹

ABSTRACT- Leaf litter decomposition research has primarily focused on single-species, though leaves do not segregate neatly in forests. Litter mixes also change as forest composition changes over time. Is decomposition of a litter mixture predictable from knowledge of the component species? Or do litters of different species interact? This study in northwestern Connecticut, examined the decomposition of Quercus rubra (red oak), Acer rubrum (red maple) and Acer saccharum(sugar maple). Often associated together both on calcareous and acidic soils, these common species have leaf litter that ranges from low to high quality. Leaves were collected during peak litterfall in 1999 from two calcareous and two acidic sites. A total of 420 fiberglass-mesh litterbags with each species individually and all possible mixtures were placed at the sites of origin in December 1999. Mass and C and N content were monitored every three months over the course of a year. At all four sites, carbon and mass were correlated, and fit Olsen's (1963) exponential decay model, while N increased initially before declining. Litter tended to decompose faster than expected in mixture with the greatest increase in the sugar maple/red oak mixture - two species most in different litter quality; effects were greater on calcareous soil than on acidic soil. These results indicate that heterogeneity of leaf litter could have significant impacts on nutrient cycling in forests.

KEY WORDS: mixed-litter decomposition, soil influences, leaf-litter decomposition