Author(s): Huusko; Ari; Korhonen; Pekka; Yrjana; Timo

Linked Author(s):

Keywords: Restoration; Forest streams; Habitat-hydraulic modelling

Abstract: Log drives were a significant part of forestry in Fennoskandia until the 1970s. This meant that especially the rapids sections of headwater streams were dredged to allow logs to pass through them quickly, resulting in uniformed channels with a simplified structure and flow. During the last decades, several extensive restoration projects have been carried out with a goal to increase the structural complexity of the dredged stream sections and further, to enhance fish productivity. By before-after designed field measurements and habitat-hydraulic modelling, we examined restoration-induced changes in the habitat structure of 15 dredged streams. After restoration, the restored stream reaches were deeper, had a larger dominant substrate size, and a slower mean velocity than in the dredged state. However, using the same set of rehabilitation measures to create a run-riffle-pool pattern into the dredged stream reaches resulted in a rather similar physical structure in all of the dredged sites after restoration. We concluded that there is a need to apply more stream-specific approaches into the region wide restoration schemes in order to preserve the diversity of forest streams that most obviously have prevailed before the dredging operations.

DOI:

Year: 2007