ALLOCHTHONOUS INPUT OF COARSE PARTICULATE ORGANIC-MATTER TO A MOROCCAN MOUNTAIN STREAM

Litter input under the warm Mediterranean climate of Northern Morocco was investigated in two locations, one upstream under a dense canopy a nd the other downstream, among sparse riparian vegetation. Quadrats we re sampled monthly, both on the banks and in the stream. Dry weight of total inputs on the banks was 474 g m-2 yr-1 upstream and 63 g m-2 yr -1 downstream, with greater spatial variance downstream. Litter accumu lation in the water was respectively 218 and 59 g m-2 yr-1. Upstream, fruit, flower and seed input exceeded in weight that of leaves on the banks. Half the fruit category was oleander that shed its fruit betwee n November and April. The evergreen leaves of oleander were shed in la te winter and early spring. Thus litter input lasted from September ti ll April. This contrasts with the earlier (summer) litter fall general ly mentioned in the Southern Hemisphere under similar climates. Peak i nputs to the Moroccan stream were delayed by about one month and inclu ded a greater proportion of light material (leaves), an indication of the participation of blow-in. A comparison of inputs on the banks and in the water under the closed canopy showed that much litter presumabl y drifted down the stream. The downstream station received partly proc essed matter from upstream. Shredders were numerous upstream, with pea k numbers in October-November and June. Collectors dominated downstrea m.