PARENT SESSION
Oral Session # 98: Biogeochemistry V: Forests; Nitrogen.
Presiding: RL Sanford
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 204.

Neighbors on the forest floor: consequences for mixes of leaf litter on differing soil types.

Gartner, Tracy^*,1, Cardon, Zoe¹, ¹ University of Connecticut, Storrs, CT

ABSTRACT- Leaf litters do not segregate neatly in forests; composition of litter mixes and the stratification of leaf types on the forest floor depend on community structure and timing of leaf drop. Also, soil properties influence decay of litter mixtures by providing nutrients, influencing moisture and temperature regimes, and housing differing decomposer communities. We studied decomposition of mixed sugar maple (Acer saccharum) and red oak (Quercus rubra) litters in four northwestern Connecticut field sites, on calcareous and acidic soils, using compartmentalized litterbags. Each litterbag contained sugar maple in equal masses in both layers, red oak in both layers, or sugar maple in the bottom compartment and red oak in the top (mimicking natural leaf stratification in the forest). Litterbags were deployed at two calcareous and two acidic sites; subsets were harvested and analyzed for mass and nitrogen changes every three months for one year. Overall patterns in decomposition across sites correlated well with soil temperature and moisture. Sugar maple decayed more quickly than red oak, but the rate of decay for both litter types changed depending on the identity of neighboring leaves. Maple decay was significantly increased (2-3%) in the presence of oak, while oak decay was either unaffected or slowed (1-2%) in the presence of maple. Changes in decay within the mixtures varied with site; decay rates in the mixture were most altered on acidic soil. Spatial heterogeneity in distributions of leaf litters could have significant impacts on nutrient cycling in forests, and the extent of the impact can vary with the soil substrate.

Key words: mixed species litter, litterbags, decomposition, calcareous and acidic soil substrates