Document Details
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Title |
Carnation Creek - forestry impacts and watershed recovery processes in a small coastal drainage | ||||||||||||||||||||||||||||
Author |
Russo, Geneen | ||||||||||||||||||||||||||||
Date |
2008 | ||||||||||||||||||||||||||||
Abstract |
The Carnation Creek project is a long-term, multi-disciplinary case study of the effects of forestry practices on a small coastal watershed. Carnation Creek is a small stream, 7.8 km long, that drains an area approximately 11 km2. The study uses an intensive, pre-treatment vs. post-treatment-impact design that currently consists of five years of pre-harvest baseline data (1970/71-1975), six years of observations from 1976-1981 when 41% of the basin was harvested, and 25 years of post-harvest studies. Another 25% of the basin was harvested in headwater areas remote from the main stream channel in the 1990s. The study features both clearcut and control sub-basins. Riparian forestry treatments vary from intensive clearcutting to variable-width riparian buffers. The overall purpose of this study is to determine the mechanisms, rates, and levels of forestry-related impacts and recovery in a harvested coastal drainage by quantifying long-term changes in biological and physical watershed processes. We are currently determining the mid-term (25-29 years) post-harvest responses to logging practices from the condition and attributes of the hydrologic regime, second-growth forests, hillslopes, stream channel network, riparian forest canopy, aquatic habitats (mainstream and tributaries), water temperatures, and salmon populations. Fish population responses measured include long-term trends in abundance, growth, age structure, survival, and smolt production. We integrate component studies of hillslope, stream channel, floodplain, and riparian processes to describe and model functional linkages and determine the ultimate consequences for channel morphology, aquatic habitats, and fish. Core data collected annually are applied to the on-going development and refinement of basin-scale models for hydrology, landslide prediction, sediment and debris budgets, channel changes, and fish habitat capability. The information gained is relevant for validating current forest practices and supporting forest policy, regulatory, and guideline development to ensure the sustainable use of forest resources, and protect watershed processes and aquatic values. This study provides key validation-research support for the B.C. Forest and Range Effectiveness Evaluation Program (FREP). Key Research Questions: Our 36-year datasets provide the necessary framework required to directly address the following questions directly relevant to forestry and watershed management: (1) What is the cumulative effect of harvesting beyond specific levels (i.e., 65% basin harvest)? (2) What is the effect on channel morphology and aquatic (e.g., salmon) habitats in both larger streams and their smaller tributaries when the riparian vegetation is removed or modified? (3) What biological changes result from these altered stream habitats? (4) How long do these physical and biological changes persist? Focus for 2007-2008: The key research question for 2007-2008 is centered around our unique opportunity to determine and directly quantify the ultimate effects of a massive pulse of sediment and debris on the entire mainstream channel and its anadromous salmon habitats and to measure resultant impacts on fish populations. Illustrating hillslope-channel connections, these materials originated from forestry-associated landslides and debris torrents that occurred over 22 years ago in three steep headwater tributaries 1 km upstream of anadromous habitats. These materials have been slowly transported downstream to now alter morphology and habitats in the entire andromous zone of Carnation Creek. Therefore, this will be a key results year for the project. For the first time since forest harvesting was implemented (1976), a substantial down-turn in the abundance of Pacific salmon directly attributable to forestry will likely be observed. Prior to this year, the relative effects of forestry practices on Carnation Creek salmon have been relatively small when compared to other sources of variation ... | ||||||||||||||||||||||||||||
Report Number |
FIA2008MR394 | ||||||||||||||||||||||||||||
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