Leaf Decomposition in Streams
Terrestrial leaf litter is an important nutrient source in streams
Leaf Decomposition1) Leaves become waterlogged and sink. May lose up to 42% mass to leaching.
2) Colonization by bacteria and fungi begins almost immediately.
3) Colonized by shredders (eat CPOM). Shredders convert CPOM to FPOM. Grazers eat algae and diatoms (FPOM).
4) Collector-gatherers (eat FPOM).
5) Collector-filterers (eat FPOM). Bacteria and fungi continue to break down CPOM and FPOM.
Leaf DecompositionMayflyCaddisflyMidgeBlack fly
Predators eat other invertebrates
Purpose of this labQuestion 1: Does presence of macroinvertebrates accelerate leaf decomposition?
Purpose of this labQuestion 2: Do leaves containing more carbon degrade more slowly? Cellulose and lignin are resistant to decomposition.
MethodsPrepare coarse-mesh maple, coarse-mesh oak, fine-mesh maple, and fine-mesh oak bags.Place and secure bags in stream/pond.Remove bags after ~1 month.Rinse macroinvertebrates from leaves and allow leaves to dry.Weigh and estimate leaf material lost.Count macroinvertebrates and sort according to functional feeding groups.