Salmon migrate between oceans and freshwater streams, serving as a link between cultures past and present, and are a symbol of knowledge and perseverance, returning to the rivers of their birth. The Pacific salmon are exposed to increasingly harsh conditions. Riparian forests are cut, affecting the ecology of the local stream system, while forest cover throughout the watershed regulates hydrological processes that define flow to downstream reaches. Therefore, our concerns are highly influenced by the modification of the riparian environment, suggesting that forestry infrastructure and logging practices are capable of significantly impacting aquatic organisms. Said infrastructure includes forest service roads (FSRs), bridges, and culverts. In terms of logging practice, clearcutting of sloped blocks and management of riparian zones (decreased riparian function) are highly relevant.
Clearcut logging practices that remove streamside timber have subsequent spatial and temporal effects on the physical and biological components of small-stream ecosystems. Examples like solar energy and nutrient inputs generally increase following logging and lead to a rise in stream temperature and primary productivity (Beschta et al., 1987). The variation in summer temperature can temporarily increase the densities and biomass of benthic macroinvertebrates, which results in a loss of resident fish (Beschta et al., 1987; Hicks et al., 1991). Another critical problem is the short term post-logging changes to instream habitat that have been reported, such as hillside slope erosion and landslides, which can input large amount of sediments and debris to nearby streams (Gregory et al., 1987). Long-term impacts are observed for decades (Pike et al., 2010). Regeneration of streamside deciduous vegetation stabilizes soils and reduces suspended sediment loading; the resultant closure of the riparian canopy serves to curb the energy-related benefits to primary producers and decreases direct radiation (Gregory et al., 1987). Another riparian issue is the removal of streamside timber, which can lead to the loss of future in-stream large wood, reducing bank stability, retention and input of organic matter, the quality and quantity of fish habitat, and fish density and biomass (Gregory et al., 1987). Naturally, the presence of large wood takes a long time to regenerate following logging and it is speculated to take over 250 years to recover to pre-harvest levels in forests of the Pacific Northwest (Murphy and Koski, 1989).
To protect the forest ecosystems in British Columbia the Ministry of Forests, Lands and Natural Resource Operations adopted the Forest Practices Code of BC Act. Our focus is on Forest Road Regulation and whether these policies adequately protect riparian and aquatic ecosystems from FSR construction (BC Act, 2003). The planning phase includes landscape measurements: width of cut slope, ditching requirements, type of roadway, fill slope, effects of the construction zone, and landslide potential (Melemez, 2012). The amount of tree damage, the average breast-height diameter of the trees in question, soil texture and surrounding geological features, and desired road gradient are further defined prior to construction (Aricak, 2008). Following the collection of this information, planning occurs in three defined stages: road layout and design, road construction, modification, and maintenance, and road deactivation. These stages are linked to the identified primary concerns and are thus negatively impacting salmon spawning habitat.