BIOGEOCHEMICAL IMPACTS OF SUBMERGING FORESTS THROUGH LARGE DAME IN THE RIO-NEGRO, URUGUAY

The Bonete, Baygorria and Palmar dams of the Rio Negro successively su bmerged complex floodplain forests. The forest area submerged was grea ter than 280 km(2) and resulted in large inputs of carbon, nitrogen an d phosphorus to the reservoirs. After 46 years wood released 40, 34 an d 71% of their original contents of carbon, nitrogen and phosphorus, r espectively. During the same period the total amount of nutrients rele ased by wood in comparison to leaves and litter is slightly less (0.7) for nitrogen, almost double (1.73) for phosphorus and more than three times (3.5) for carbon. These results suggest that wood decomposition in wafer may have a role in the trophic state of reservoirs. (C) 1998 Academic Press.