Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.

The impact of riparian restoration on channel complexity and soil nutrients

John Patrick Laceby , Nina Saxton , Kate Smolders , Justine Kemp , Stephen Faggotter , Tanya Ellison , Doug Ward , Morag Stewart , Michele Burford

Abstract

Restoration of riparian vegetation may reduce nutrient and sediment contamination of waterways while potentially enhancing stream channel complexity. Accordingly, this study uses a paired-site approach to investigate the effects of mature regrowth riparian vegetation on river channel morphology and soil nutrients (i.e. nitrogen and phosphorus), comparing four sites of degraded (pasture) and reforested reaches. A revised rapid assessment of riparian condition (RARC) was used to validate the site pairings. Riparian soil nutrient and elemental geochemistry were compared between paired sites along with two parameters of channel width complexity and two for channel slope complexity. The RARC analysis confirmed the validity of the paired site design. The elemental geochemistry results indicated that underlying geology may impact the paired site analyses. Reaches with mature regrowth vegetation had greater channel width complexity but no difference in their riverbed slope complexity. Additionally, degraded reaches had higher soil nutrient (i.e. nitrogen and phosphorus) concentrations potentially indicative of the greater nutrient retention of pasture grass sites compared to mature regrowth forested reaches with less ground cover. Overall, this research indicates that restoring mature regrowth riparian vegetation may increase river channel width complexity, though may require canopy management to optimize nutrient retention potential necessary to maximize the impact of riparian restoration strategies on freshwater environments.

MF16338  Accepted 09 February 2017

© CSIRO 2017