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Abstract:
Streamside wetlands cover large areas in the tropics because of high
stream density, high discharge fluctuations, and, in the lowlands, a
flat relief. In streams shaded by streamside forest, food webs depend on
carbon input from the wetlands and the uplands because of low instream
primary production. However, litter break down in tropical streams is
slower than in temperate ones, because of low nutrient level and hard
consistence of the litter. The aquatic shredder community is
impoverished in species and in abundance. Litter break down in the
wetlands and uplands by terrestrial organisms and the input of fine
particulate and dissolved organic matter during spates and floods, but
also the input of high valuable external food sources, e.g., terrestrial
insects and fruit, seem to be more important for tropical streams than
for temperate ones. Despite of a very small database on tropical stream
organisms and dramatic taxonomic gaps, overall species diversity in
tropical streams seem to be not higher than in temperate ones, however
with differences within different plant and animal families. A greater
biodiversity may occur in the streamside wetlands, probably related with
the larger number of flood tolerant tree species. The importance of the
River Continuum Concept and the Flood Pulse Concept for tropical streams
and streamside wetlands is discussed. The role of an intact network of
streamside wetlands for biodiversity in the landscape and the need for
the protection of streamside wetlands is focussed.
