Fungal biomass and decomposition in Spartina maritima leaves in the Mondego salt marsh (Portugal)

Spartina maritima (Curtis) Fernald is a dominant species in the Mondego sal t marsh on the western coast of Portugal, and it plays a significant role i n estuarine productivity. In this work, leaf litter production dynamics and fungal importance for leaf decomposition processes in Spartina maritima we re studied. Leaf fall was highly seasonal, being significantly higher durin g dry months. It ranged from 42 g m(-2) in June to less than 6 g m(-2) duri ng the winter. Fungal biomass, measured as ergosterol content, did not diff er significantly between standing-decaying leaves and naturally detached le aves. Fungal biomass increased in wet months, with a maximum of 614 mu g g( -1) of ergosterol in January in standing-decaying leaves, and 1077 mu g g(- 1) in December, in naturally detached leaves, decreasing greatly in summer. Seasonal pattern of fungal colonization was similar in leaves placed in li tterbags on the marsh-sediment surface. However, ergosterol concentrations associated with standing-decaying and naturally detached leaves were always much higher than in litterbagged leaves, suggesting that fungal activity w as more important before leaf fall. Dry mass of litterbagged leaves decline d rapidly after 1 month (about 50%), mostly due to leaching of soluble orga nic compounds. After 13 months, Spartina leaves had lost 88% of their origi nal dry weight. The decomposition rate constant (k) for Spartina maritima l eaves was 0.151 month(-1).