Allochthonous matter input in two different stretches of a headstream (Itatinga, Sao Paulo, Brazil)

In two streches of the Itauna stream, one in a gallery forest and the other in an herbaceous vegetation zone, litter matter input (sorted by leaves, l igneous and reproductive components) were measured during a year. In the ga llery forest stretch, the direct input and lateral transport attained 713 g .m(-2).year(-1) and 421 g.m(-1).year(-1), respectively. In contrast, the he rbaceous vegetation stretch showed a direct litter input and lateral transp ort of only 86 g.m(-2).year(-1) and 124 g.m(-1).year(-1), respectively. The empoverishment of riparian vegetation had a significant effect on the decr ease of allochthonous input to stream mainly by direct input. Peaks of dire ct input into Itauna stream occurred during late dry season and in the earl y wet season. They were attributed to leaf fall from riparian trees and to enviromental conditions, such as wind. In March, which was the rainy season in this region, a peak of lateral transport was observed mainly in the her baceous vegetation stretch, probably induced by runoff.