Does adding wood to agricultural streams enhance biodiversity? An experimental approach

Abstract

Riparian clearing and the removal of wood from channels have affected many streams in agricultural landscapes. As a result, these streams often have depauperate in-stream wood loads, and therefore decreased habitat complexity and lower levels of in-stream biodiversity. The introduction of wood was investigated as a possible rehabilitation technique for agricultural streams. Wood was re-introduced to eight streams in two separate high-rainfall, intensively grazed regions of Victoria, Australia and the effect on aquatic macroinvertebrate communities was measured. The addition of wood increased overall family richness and the richness of most functional feeding groups occupying edge and benthic habitats within the stream. Wood addition led to less overlap between benthic and edge macroinvertebrate communities, suggesting increased habitat heterogeneity within the stream ecosystem. Of all sampled habitats, wood supported the greatest density of families and was colonised by all functional feeding groups. Wood habitats also had the highest overall richness and supported the most taxa that were sensitive to disturbance. These findings suggest that re-introducing wood to agricultural streams is an appropriate rehabilitation technique where those streams are affected by reduced habitat complexity. Additional work is needed to confirm these findings over larger spatial and temporal scales.

From forests to cattail: how does the riparian zone influence stream fish?

“…Allochthonous organic matter, such as leaves and branches, serves as substrate for the development of microorganisms taken as food by invertebrates and fishes (e.g., Angermeier & Karr, 1983;Pusey & Arthington, 2003), offers shelters for ichthyofauna (Angermeier & Karr, 1983), works as visual reference that helps visual guidance and navigation for fishes (Crook & Robertson, 1999) as well as influences the hydraulic profile of water courses (Brooks et al, 2004;Daniels & Rhoads, 2004). There is evidence that the reduced intake of these elements may cause a reduction in species number, density and biomass of fishes (Angermeier & Karr, 1983;Neumann & Wildman, 2002;Lester et al, 2007;Schneider & Winemiller, 2008). Additionally, there is much evidence that the patterns of assemblages are also influenced by the width and type of adjacent forest covering (Bojsen & Barriga, 2002;Lorion & Kennedy, 2009;Casatti et al, 2009;.…”

Alterações no Código Florestal Brasileiro: impactos potenciais sobre a ictiofauna

“…Há várias evidências científicas de que a diminuição do aporte destes elementos pode causar a diminuição da quantidade de espécies, densidade e biomassa dos peixes (Angermeier & Karr 1984, Neumann & Wildman 2002, Lester et al 2007, Schneider & Winemiller 2008. Da mesma maneira que o sistema terrestre exporta elementos orgânicos para o riacho, este os exporta para o sistema terrestre, principalmente através da eclosão de insetos que passam a fase juvenil na água (Marczak & Richardson 2007).…”

Integrating Limiting-Factors Analysis with Process-Based Restoration to Improve Recovery of Endangered Salmonids in the Pacific Northwest, USA

“…Such outcomes have been reported from a variety of locations and watershed contexts, particularly channels in highly disturbed urban watersheds where altered flow regimes and water chemistry are typically as or more impacted than physical habitat (e.g., [6][7][8][9][10][11]; Figure 1). In less disturbed watershed settings, results are commonly more biologically successful, but rarely do they approach full recovery of the instream and biological conditions found in fully undisturbed settings (e.g., [12][13][14][15][16][17][18]). …”