Vegetation, such as leaves and needles, plays many critical roles in the productivity of riparian terrestrial and aquatic habitats. However, only a few organisms, primarily insects, feed directly on riparian vegetation. Instead, most organisms derive their nutrition from food chains, which are supported at their base by the breakdown and incorporation of decaying leaf litter. Leaf litter breakdown in both terrestrial and aquatic systems is a complex interaction among chemical, physical, and microbial processes that plays a vital role in the trophic dynamics of riparian forests. The rate of leaf litter decay is affected by both internal factors of the litter—the chemical and physical characteristics of the leaves themselves—and external environmental factors.

In this study, we are experimentally examining the influences of litter type and stand type on leaf litter decay in both the terrestrial and aquatic environment. Questions addressed in this study include the following: Does litter type (Douglas-fir vs. red alder) influence the rate of litter breakdown? Does decompositional environment (Douglas-fir vs. red alder-dominated stands) influence breakdown rates for common litters? Is there an interaction between environment and litter type? How does a wide range of initial litter quality (lignin:nitrogen ratio) affect the breakdown rate of litter from a single species (Douglas-fir)? Does externally added nitrogen (N) affect the breakdown rate of Douglas-fir litter? Is there an interaction between initial litter quality and externally added N? These questions will be examined in the context of the terrestrial and aquatic environments.

For additional information about this research study see the CFER Annual Report. (2.2 MB)