DECOMPOSITION OF PHRAGMITES AUSTRALIS LITTER IN SEASONALLY FLOODED AND EXPOSED AREAS OF A MANAGED REEDBED

Most studies on the decomposition of Phragmites australis have concentrated on permanently submerged or standing litter. The present study examines the dynamics of leaf and stem litter breakdown in seasonally flooded and permanently exposed areas in a managed reedbed. Seasonal flooding and summer drawdown are employed as part of the management to prevent litter accumulation. Fine mesh (0.25 mm) and modified design, coarse mesh (5-mm) bags were used. In the permanently exposed area, leaf and stem material lost 42% of their dry weight after 18 months and 47% after 30 months. In the seasonally flooded area, depending on mesh size, leaf material lost 74–79% and stem material 60–79% of its dry weight over the same time periods. Examination of individual breakdown rates demonstrated that fastest weight losses occurred following summer drawdown, with well-oxygenated, warm, damp litter. Drying of the litter and re-flooding of the reedbed led to slowing or complete cessation of breakdown. Maintenance of damp conditions throughout the summer exposure period would maximize breakdown rates.