Abstract:
Tropical montane streams produce a disproportionately large amount of the sediment and carbon that reaches coastal
regions and have often been considered to be distinct fluvial systems. They typically drain orogenic terrains that have not
been recently glaciated, but have undergone climatic changes throughout the Pleistocene and currently receive
2000–3000 mm or more of precipitation each year. Steep gradient reaches with numerous boulders, rapids, and waterfalls
that alternate with lower gradient reaches flowing over weathered rock or a thin veneer of coarse alluvium characterize these
streams. Although their morphology and hydrology have distinctive characteristics, they do not appear to have diagnostic
landforms that can be solely attributed to their low-latitude locations. While they are relatively understudied, an emerging
view is that their distinctiveness results from a combination of high rates of chemical and physical weathering and a high
frequency of significant geomorphic events rather than the absolute magnitudes of individual floods or other geomorphic
processes. Their bedrock reaches and abundance of large and relatively immobile boulders combined with their ability to
transport finer-grained sediment also suggest that the restorative processes in these systems may be less responsive than in
other fluvial systems.