Rehabilitating Agricultural Streams in Australia with Wood: A Review

Abstract

Worldwide, the ecological condition of streams and rivers has been impaired by agricultural practices such as broadscale modification of catchments, high nutrient and sediment inputs, loss of riparian vegetation, and altered hydrology. Typical responses include channel incision, excessive sedimentation, declining water quality, and loss of in-stream habitat complexity and biodiversity. We review these impacts, focusing on the potential benefits and limitations of wood reintroduction as a transitional rehabilitation technique in these agricultural landscapes using Australian examples. In streams, wood plays key roles in shaping velocity and sedimentation profiles, forming pools, and strengthening banks. In the simplified channels typical of many agricultural streams, wood provides habitat for fauna, substrate for biofilms, and refuge from predators and flow extremes, and enhances in-stream diversity of fish and macroinvertebrates.Most previous restoration studies involving wood reintroduction have been in forested landscapes, but some results might be extrapolated to agricultural streams. In these studies, wood enhanced diversity of fish and macroinvertebrates, increased storage of organic material and sediment, and improved bed and bank stability. Failure to meet restoration objectives appeared most likely where channel incision was severe and in highly degraded environments. Methods for wood reintroduction have logistical advantages over many other restoration techniques, being relatively low cost and low maintenance. Wood reintroduction is a viable transitional restoration technique for agricultural landscapes likely to rapidly improve stream condition if sources of colonists are viable and water quality is suitable.

Generalized Linear Models to Identify Key Hydromorphological and Chemical Variables Determining the Occurrence of Macroinvertebrates in the Guayas River Basin (Ecuador)

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Ecoengineering with Ecohydrology: Successes and failures in estuarine restoration

“…While providing beneficial services in terms of wind-driven wave erosion mediation and ecological functions using tree debris (e.g. habitat and biodiversity enhancement) warrants engineering, the efficacy and collateral ecological functions observed in rivers (Larson et al, 2001;Lester and Boulton, 2008) are often lacking in estuarine and coastal applications.…”

Restoration in Integrated River Basin Management

“…Woody debris are often added directly in the channel, and new woody plants have been reintroduced along the river course to address the lack of any riparian vegetation on riverbanks in cultural landscapes (Reich et al 2003). Both instream and riparian wood enhancement may improve the diversity of fish and macroinvertebrates, increase storage of organic material and sediment, and strengthen bank stability (Lester and Boulton 2008). Compared to other restoration techniques, such measures have logistical advantages and generally require low costs and low maintenance.…”