SEASONAL DIFFERENCES IN THE DECOMPOSITION OF Typha angustifolia LEAVES IN A MEDITERRANEAN RIVER

This study evaluated seasonal differences (spring and summer) in the processing of Typhu ungustifolia leaves in a Mediterranean river. The experiment extended over 120 days, corresponding to six sampling periods for each experiment. Leaves (5 g) were placed in 0.5 cm mesh-size bags. After recovering the sample, macroinvertebrates inside the leaf bags were retrieved and the leaves preserved by freezing. The dry mass, nutrients (N and P), cellulose, hemicellulose and lignin contents were measured. The litter breakdown proceeded at an exponential rate, higher in spring (k = 0.0098 d-') than in summer (k = 0.003 1 d-'). This coincided with the highest current speed and dissolved oxygen concentration. The decay patterns of lignin, cellulose and hemicellulose suggest the existence of two phases dunng the aquatic decomposition, influenced by the previous terrestrial conditioning.