Abstract ID: 535

Effects of reduced-impact logging on stream characteristics and fish assemblages in Central Amazonia

In Amazonia, large areas containing thousands of streams are logged for reduced-impact logging. However there are few studies evaluating temporal and spatial effects of this management on streams and their associated fauna. We investigated the effects of reduced-impact logging on stream-fish composition and environmental variables in streams in a forest in Central Amazonia. Short-term effects were tested in one annual production unit, where we sampled eleven streams before and after logging. Longer-term effects were tested in sixteen annual production units already logged 1-12 years. We surveyed streams in logged area and others in control areas. We sampled fish composition and stream characteristics in 50meters stream sections in annual production units. In the short-term, fish composition did not differ before and after reduced-impact logging, although the pH, discharge, depth, canopy cover, mean current velocity and substrates types were differed from conditions before logging. In the long-term, environmental stream characteristics in logged plots did not differ from controls. However, fish relative abundance was different from control plots. Presence/absence composition was negatively related to time since logging. Common species had higher abundances in logged areas. However, there was no evidence of species loss. In a few years the effect on the stream physical/chemical characteristics were undetectable, but detectable effects of reduced-impact logging on fish composition seems to persist even after 12 years. For Amazonian streams, reduced-impact logging appears to be a viable alternative to clear cut practices, which severely impact aquatic communities. However, it is important that monitoring is continued to evaluate the long-term effects on stream organisms, and determine whether alteration of management practices could reduce impacts even further.

Session:  LCLUC and Human Dimensions - Sustainable forest management.

Presentation Type:  Oral