THE BREAKDOWN OF DEAD LEAVES BURIED IN THE SEDIMENT OF A PERMANENT STREAM IN MOROCCO

The breakdown of dried willow leaves in 0.5 cm-mesh bags buried at a d epth of 20 cm in the sediment of Oued Zeghzel was investigated in two stations. These stations were located in the upper course and in the m iddle course of the stream. Breakdown rates were compared with former data on leaves resting on the bottom of the stream. The breakdown rate of buried leaves was the same in both stations and the same as that o f benthic leaves in the middle course of the stream, where shredders w ere scarce. It was slower than that of benthic leaves in the upper cou rse, where shredders were numerous and active. Sediments with and with out leaves were colonized at the same rate by invertebrates.