Riparian zones help maintain the integrity of small stream ecosystems by providing shade, large organic debris, cover for stream-dwelling fish, and energy in the form of allochthonous organic matter, as well as stabilizing streambanks and intercepting sediments. Because logging practices that remove streamside timber have the potential to alter a stream?s physical and biological characteristics, protective measures such as the Forest and Range Practices Act were enacted in British Columbia to help maintain riparian functions around fish-bearing streams, most commonly through the retention of buffer strips. Although there exists a relatively large body of literature on the post-harvesting effects of streamside logging practices, the vast majority of fish-forestry research has been conducted in coastal areas (this despite the fact that much of the timber supply in the immediate future will be from interior boreal & sub-boreal forests). Furthermore, most fish-forestry studies encompass a relatively short post-harvesting timeline (< ~ 10-15 years), leading to an additional dearth of longer-term data on stream ecosystem responses to the removal of riparian timber. Our scientific knowledge is therefore heavily biased towards short and medium-term post-logging responses in coastal systems, with little information on interior streams and on longer-term effects. This information is sorely needed given the large-scale salvage operations currently being undertaken in response to the mountain pine beetle (MPB) epidemic throughout BC?s interior regions.
The distribution of bull trout (Salvelinus confluentus, a blue-listed species in BC) and the current & projected spread of the MPB in north-central BC show considerable overlap. Furthermore, there is an acknowledged dearth of information regarding the responses of stream-dwelling bull trout and their fluvial habitats to the kind of harvesting practices that can be expected under the threat of MPB salvage-logging. Our proposal seeks to bridge this knowledge gap by using a comparative survey experimental design comprising forested streams (controls) and watersheds that are currently affected by MPB to assess the shorter-term effects of salvage-harvesting on streams and their bull trout populations. In addition, because the Prince George region has undergone extensive logging in the past 30 years (with much of the logging around streams having been conducted without buffer strips), we will use watersheds that have historically been affected by insect outbreaks to assess the projected longer-term impacts of the kind of large-scale salvage logging operations currently underway in north-central BC. Such a comparative survey approach has been used successfully by the team members to assess rainbow trout physiological stress responses to logging in a previous FRBC-funded project (see Mellina et al. 2005a in team member CV), and it can act as a springboard from which to launch future logging-related research on this species (e.g., to implement a case-study experiment involving pre-and post-logging data).
Recent work conducted in north-central BC by the team members (FIA project Y051038) suggested that short and medium-term effects of clear-cut logging on small lake-headed streams and their rainbow trout populations were relatively modest despite the removal of all large-diameter trees within the riparian zones. However, the effects of streamside clear-cut logging on bull trout in this region are poorly understood. Bull trout have a different life-history and thermal requirements from rainbow trout (e.g., the former are cold-water (<12 °C) adapted and are fall spawners, whereas the latter are more tolerant of warmer temperatures (15-17 °C) and are spring spawners). These differences can be crucial in determining how individual fish (and ultimately populations) respond to clear-cut logging. For example, stream temperatures in small headwater streams in north-central BC are typically cold a ...
Hinch, Scott G., Mellina, Eric. 2009. Stream habitat and bull trout (Salvelinus confluentus) responses to MPB riparian salvage harvesting in north-central British Columbia. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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