Mass loss, fungal colonization and nutrient dynamics of Phragmites australis shoots during plant senescence and standing litter decomposition

We examined mass loss, fungal biomass, and nutrients dynamics of <i>Phragmites australis</i> shoots (leaf-blades, leaf-sheaths and culms) during senescence and standing litter decomposition in a lake littoral reed stand. Naturally standing shoots of <i>P. australis</i> were tagged while living and periodically collected over one year. Collected shoots were separated by organ in three differing canopy heights (upper, mid, and base) and analyzed for mass loss (area specific mass), fungal biomass (ergosterol), and litter nutrient concentrations (N and P). Fungal biomass, nutrients and rates of mass loss differed significantly among plant litter organs and heights. For example, leaf blades lost considerable mass in the standing position (up to 31% in 80 days). Corresponding mass loss of leaf sheaths and culms were 25% and 20%, respectively. Fungal biomass increased during plant senescence and decomposition, reaching a maximum of 6, 7 and 2% of the total detrital mass in leaf-blades, leaf-sheaths and culms, respectively. Patterns of mass loss, nutrients, and fungal biomass were consistent with the successive senescence, death and decay of plant shoots. Results of this study indicate that notable mass loss of <i>P. australis</i> shoots can occur in standing position, which is mediated by both plant and microbial processes.