Forest Investment Account (FIA) - Forest Science Program
FIA Project Y081216

    Long-term stream habitat and rainbow trout responses to alternative riparian management in north-central British Columbia
 
Project lead: Hinch, Scott (University of British Columbia)
Author: Hinch, Scott G.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
Although most fish-forestry research has been conducted in coastal areas, the bulk of the world’s timber supply for the immediate future will be from interior forests. Studies documenting the impacts of forest practices on small streams in these regions are rare, and this proposal seeks to address this gap in our knowledge. Our proposed research will nearly double the time frame over which post-logging observations are made on a set of experimentally logged interior streams. This is extremely important as many post-logging effects to streams are not evident until 10+ years. Specifically, 3 small, lake-headed S3 streams were monitored prior to (1997) and following (1998-1999, 2004) streamside logging (total post-logging observations of 6 years). The logging treatments applied to the streams were novel, allowing for the removal of all commercial timber within the riparian reserve zones while retaining non-commercial coniferous trees and deciduous vegetation. Such a prescription actually violated the Forest Practices Code of the day, but under the present Forest Practices and Range Act, it would be allowed and is presently being used. Also, they mimic aggressive riparian salvage logging now occurring due to mountain pine beetle (MPB) infestations, and our proposal would provide the only longer-term assessment of fish/habitat from MPB logging practices in north-central BC. The proposal extends data collection to 10 yrs post-harvest and builds on our previous FRBC, FII, FSP projects conducted in northcentral BC. To date we have found: a) Logging reduced streamside canopy cover by 50% - the remaining streamside vegetation continued to provide shade and future supply of large instream wood. b) Stream temperature changes following logging were relatively modest (< 1 C on average) when compared to headwater streams (5-7 C). c) Logging treatments did not cause detectable changes in rainbow trout movement patterns, whereas trout growth was greater in the logged streams than in the control stream (which we attributed to earlier emergence from stream gravels and a more conducive thermal environment). d) Post-logging summer suspended sediment levels remained low, and average summer dissolved oxygen (DO) concentrations remained above the level required for salmonids to function without impairment. e) The number of pools was unaffected, and reductions in pool area and volume of approximately the same magnitude were observed in both the treatment and control streams. f) Rainbow trout densities and biomass were variable across years, with > 90% of the populations in both streams comprising young-of-the-year (YOY) and age 1 – 2 trout. The above results provide much needed information on stream ecosystem responses to logging practices in interior regions, but it only provided a relatively short-term (1-6 years) post-logging perspective. Although many habitat and fish measures were not affected in the short-term, theoretical models indicate that we might expect to find significant changes 10+ years post-logging. In this proposal, we seek to re-visit the same 3 lake-headed streams monitored in our previous studies in order to assess longer-term (10 years) responses to the logging treatments. Case study field experiments (that incorporate before and after assessments) which examine the effects of streamside harvesting on small stream ecosystems are rare in coastal regions, but they are virtually non-existent in temperate interior regions and none focus on lake-headed streams (which are abundant in boreal and sub-boreal landscapes). Our previous results underscore the natural variability inherent in small stream ecosystems, and highlight the need for multi-disciplinary and long-term research to better understand the impacts of streamside clear-cut logging. This project will establish the first long-term, before and after logging, fish-forestry case study (> 10 years, the equivalent to 3 full generations of rainbow trout) in temperate, interior regions in BC, and will complement a similar long-term, multi-stream experiment being carried out in small coastal streams by our collaborators in the Malcolm Knapp Research Forest. Our proposed research is therefore aimed at assessing longer-term responses to streamside logging through comparisons with our prior, shorter-term results. The following questions will be addressed: 1) Have summer stream temperatures and canopy cover levels recovered or exceeded pre-logging conditions? Can we predict recovery rates based on our prior and proposed data? 2) Changes in type of stream shading post-logging is important. A deciduous canopy, while contributing shade, may not contribute to stream thermal recovery to the same degree as a coniferous one. Stream temperature and canopy cover data collected as part of this proposal would be used to test the applicability of the Mellina et al. (2002) predictive model to such post-logging conditions, and to fine-tune the model if necessary. 3) Are rainbow trout densities, biomass, distribution and condition now affected by logging as theoretical models suggest? 4) Have stream habitat features begun to deteriorate as models suggest? 5) Are inter-annual changes in habitat and fish responses related more to inter-annual environmental fluctuations and to the natural differences inherent among the streams, as our short-term data indicate, than a response to logging? 6) Are longer-term post-logging habitat and trout responses still less severe in lake-headed streams than headwater streams as our shorter term data indicated? We will use data collected by our research partners (MoF, DFO, and UBC) in headwater streams in coastal and interior regions of BC with which to make comparisons. This proposal is not only relevant to the eligible, high-priority research topics identified for 2007/08, but also addresses several longer-term goals identified in the Research Strategy for 2006-2016, under both the Sustainability and MPB Programs. For example, within the theme of Riparian Ecology and Stream Management, our proposal not only addresses the sensitivity of small stream ecosystems to alternative riparian management strategies (priority a), but can also provide scientific data related to the consequences of MPB salvage and management on riparian character and function of small streams and other aquatic habitats (priority c). Within the Watershed Function theme (a MPB focus for 2007/08), our proposed research will evaluate the physical, biological and cumulative effects of forest management on channel morphology and aquatic habitat. Our results will provide the necessary scientific information required to support policy and guideline development, as well as enhancing the ecological basis for sustainable forestry practices and the quality of management decision-making through an improved knowledge base. Our proposal will also advance forest science knowledge (sorely needed for interior regions) through practical adaptive management approaches.
Contact: Hinch, Scott, (604) 822-9377, shinch@interchange.ubc.ca

    Deliverables:

Executive Summary (37Kb)

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Updated August 16, 2010 

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