Research in the Physical Ecology Laboratory at the University of Northern British Columbia (UNBC) has focused on understanding: (1) the relationship between stream hydraulics and stream organisms (periphyton and invertebrates); and  (2) the influence of forestry practices (primarily riparian buffers) on stream ecology.

Research Themes
Our laboratory has been involved in two major research projects associated with the hydraulic habitats of stream organisms.

Our present project, The Efficacy of Riparian Buffers in Maintaining the Hydraulic Habitats of Stream Benthos:  Substrate-Fluid and Biological Interactions, will examine the interaction of (1) forestry practices, (2) near bed flows, and (3) stream ecology in an effort to determine whether increased sorting and sediment load caused by forestry leads to changes in hydraulic habitats of stream periphyton.

Our original project, Biophysical Structuring of Aquatic Habitats in Riparian Zones, involved an in-depth analysis of (1) stream biodiversity, which focused on the characterization of biodiversity at different spatial and temporal scales, and different riparian management; (2) stream productivity, which examined primary and secondary production in streams with different riparian management; and (3) stream hydraulic habitats, which focused on the biophysical drivers of stream biodiversity and how these drivers are affected by riparian management.

Project Leader	Project	Supported by
Dr. Josef Daniel Ackerman Environmental Studies Program University of Northern British Columbia Prince George, BC, Canada V2N 4Z9 Tel:  250-960-5839  Fax: 250-960-5539
email: ackerman@unbc.ca  www: index.htm	Forest Renewal British Columbia	Natural Sciences & Engineering    Research Council of Canada

Current Research (2001 - 2005)

The Efficacy of Riparian Buffers in Maintaining the Hydraulic Habitats of Stream Benthos:  Substrate-Fluid and Biological Interactions

Project Overview
Despite the fact that riparian reserves are designed to mitigate the effects of forestry practices in and around forest streams, aquatic habitats and organisms are impacted by forestry practices.  The underlying mechanisms leading to these impacts are likely related to the altered hydraulic habitats of stream organisms.  This proposal will examine the interaction of forestry practices, near bed flow, and biology in an effort to determine whether increased sorting and sediment load caused by forestry leads to changes in hydraulic habitats.  These results will be valuable for resource managers and policy makers interested in achieving low impact and sustainable forestry to preserve aquatic habitats, and to aquatic scientists interested in the functioning and ecology of forest streams.

Background/Rationale
Riparian reserves are designed to mitigate the effects of forestry practices in the ecologically-sensitive regions in and around forest streams.  Nonetheless, impacts of forestry practices on aquatic habitats, species composition/biomass, and fisheries do occur and are well known.  Little is known, however, of the underlying biophysical mechanisms that cause these impacts or how these impacts can be mitigated more effectively.  The implication from several sources is that forestry practices may impact or alter the link between hydraulics and benthic substrates in the near-bed flow of streams.  These near-bed flows, which vary according to the substrate-flow interactions (e.g., substrate spacing, embeddedness, relative water depth), influence the morphology, physiology, behavior, and distribution (i.e., habitats) of benthic organisms including periphyton and invertebrates.  Any changes to these hydraulic habitats by forest practices, therefore, affect the productivity and functioning of forest streams.  Consequently, the efficacy of mitigation practices could be evaluated by examining substrate-flow interactions within streams and to determine whether changes have occurred.

Preliminary results from a previously funded FRBC study in the Torpy River Watershed indicate that (1) periphyton growth tended to be greater on more embedded substrates, and (2) that substrates in streambeds of harvested streams with riparian reserves tended to become more embedded (less rough) in the years following forest harvest.  The consequence of this type of change would be an increase in the productivity of these types of streams, which could lead to watershed-wide changes in water quality that would ultimately impact aquatic values.  Additional research in this watershed is needed to verify these results in a statistically valid sense (i.e., increase the sample size).  In addition, a similar study among watersheds (i.e., over larger spatial scales) should provide evidence to determine whether this is a general result that can be applied elsewhere.  The results of the proposed research would provide a significant practical advance in terms of assessing the efficacy of riparian reserves in mitigating forestry practices and hence maintain watershed processes and protect aquatic values.  Moreover, it would provide a significant scientific advance in terms of determining the hydraulic habitats and functioning of stream organisms.

Graduate Student Opportunity
Funding is available immediately for a (M.Sc. or Ph.D.) graduate student interested in the examining the relationship between stream hydraulics and the ecology of stream organisms, and how they are affected by forestry practices.  The research involves field-based research in majestic and rugged forest streams in north central British Columbia , and in the well-equipped Physical Ecology Laboratory at the University of Northern British Columbia..

This exciting opportunity is ideal for (1) students with backgrounds in the physical sciences/engineering who desire training in biological aspects of environmental sciences and/or (2) students with backgrounds in the ecological/ biological sciences who desire training in physical aspects of environmental sciences.

Interested students are encouraged to contact Dr. Joe Ackerman  (ackerman@unbc.ca).

 
Past Research (1997 - 2000)

Biophysical Structuring of Aquatic Habitats in Riparian Zones: The Effects of Forests Practices

Abstract
Forest practices affect aquatic ecosystems through changes to water quality (e.g., temperature, sedimentation) although the mechanisms by which these occur is not well understood.  This report examines the biophysical structuring of aquatic habitats in riparian ecosystems as they are affected by forest practices.  Specifically, the efficacy of riparian reserve zones are examined as they relate to stream biodiversity, productivity, and hydraulic habitats.  The results of a series of experimental and statistical evaluations reveal that riparian reserve zones provide some short-term mitigation to aquatic processes, as they are intermediate in their severity compared to streams that have been clear cut.  Regardless, evidence of forestry impacts on aquatic processes remain, and are influenced by the quality of the riparian reserve.  Long-term changes to streambeds, even in the presence of riparian reserve zones, are predicted to alter stream productivity and biodiversity.  The forestry industry should consider these points and re-evaluate the role and examine the efficacy of riparian buffer strips in the mitigation of forest practices.

Project Participants:
Postdoctoral Fellows:  Dr. N. Yonemitsu 97; Dr. S. Ahmed 99
Research Technician: Jen McConnachie 99-00
Graduate Students:  Trent Hoover 96-00 (M.Sc. in Prog), Jacquie Lee 97-00(M.Sc. 2000)
Student Assistants:- (1) Mike Nishizaki 96-99 (B.Sc.1998), (2) Terri Fortune 97-99 (B.Sc.1999), (3) Leanne Wilson 97-98 (B.Sc.1999), (4) Shelley Rosenthal 98-99 (B.Sc.1999); (5) Julia Bolton 98-99(B.Sc.1998); (6) Julianne  Trelenberg 99; (7) Dan Gable 98; (8) Michelle Oster 98; (9) Carolyn Poirier 96-97; (10), Corry Moes 97; (11) Michelle Dube 97; (12) J.E. Watson 97; (13) Michelle Dube 97; (14) Deanne Demant 96; (15) Lisa Shelest 96; and (16) Steve Bruce 96.
Fabricator: John Harris (1997)

Project Background and Rationale
We are examining the effects of forest practices on the biophysical structuring of microhabitats and biodiversity of aquatic organisms in riparian ecosystems. Riparian zones are ecologically-sensitive ecosystems that serve as multiple links between soil, air, water, and ultimately forest and sea. Present forest practices alter important aspects of the hydrology of riparian ecosystems including flow, sedimentation, water temperature, and the timing and magnitude of snowmelt and runoffs. These physical changes to aquatic habitats have been recognized in terms of altered species composition/biomass and related effects on fisheries. However, little is known about the biophysical mechanisms involved and how to mitigate them.

The current British Columbia Forest Practices Code designates the size of riparian reserve strips, which are unforested areas adjacent to forest streams, which are designed to minimize impacts on aquatic systems and to maintain the fisheries and wildlife value” of the area. While this approach is sensible, we do not know whether the strips are sufficiently wide to protect the aquatic habitats. Moreover, the nature of the habitats in riparian zones for most aquatic species is not well understood. Consequently, it is difficult to assess the effects of forest practices on biodiversity without characterizing the organisms and communities that are present.

Our project focuses on the creeks and streams within the Torpy River watershed, which is currently being forested due to insect damage. The Torpy River, which is east of Prince George, is dominated by Spruce and Subalpine Fir (Sub Boreal Spruce; SBS VK) in the higher elevations and Western Red Cedar and Western Hemlock (Interior Cedar Hemlock; BEC zone; ICH VK2) in the valleys. These forest communities overlay glacio-lacustrian deposits.

Map of the Torpy River Watershed. The site locations referred to in this study were located in the lower portion of the Torpy River beginning at km zero, which was located on the road just south of the confluence of the West Torpy River and the Torpy.

Our Goals and Objectives:
Our objectives are directed towards the issue of the efficacy of riparian reserve strips to aquatic organisms in riparian zones. Specifically, we are examining whether reserve strips of different sizes (including no strips) lead to changes in the hydraulic habitats of aquatic organisms and hence their biodiversity. Our approach is interdisciplinary in the sense that it includes both physical characteristics of habitats (fluid dynamics, chemistry) with more traditional biological and ecological ones (species lists, community structure, life history).

Some Observations and Conclusions:

(A) Stream Biodiversity

•  The biodiversity of forest streams is affected by forestry activities and riparian management practices.  This was evident in the statistical evaluation of benthic insect larvae and the occurrence of the freshwater clam (Pisidium casertanum) from the Lower Torpy River watershed.  In the former, it is likely that forest practices have altered the biophysical structure of streams (see below), while in the latter activities such as road building have augmented available soft-sediment habitats for freshwater molluscs.

Taxonomic Richness (species number) of macroinvertebrates in forest streams with 0 = adjacent areas logged within 10 years, 1 = adjacent areas logged > 10 years ago, and 2 = adjacent forest with no logging history (i.e. intact riparian canopy). The overall effect is significant (F(2, 114) = 11.24, P = 0.0229), Scheffé’s post hoc tests reveal that while there is a significant difference between streams with recently logged adjacent areas and streams with unlogged adjacent forests (i.e. between 0 and 2).

(B) Stream Productivity

• The removal of riparian vegetation has an affect on the productivity of streams on short time scales through increased periphyton growth (i.e., canopy < foliated < defoliated < clear cut).  Given that a riparian buffer of 10 m is not statistically different from those of a control stream, one could conclude that buffers are effective in mitigating forestry practices, but the quality of riparian buffer is of equal importance.  This is borne out by the fact that a stream with a 10 m defoliated buffer was more like the clear-cut stream.  Considerable replication of these results in other watersheds and biogeoclimatic zones will be needed before a definitive conclusion can be made on the precise nature of the quantity (e.g., width) and quality (e.g., tree density; canopy leaf area index) of riparian buffer strips in harvested regions.

Extracted Chlorophyll a density measured on artificial substrates deployed in forest streams.

• Forestry activities lead to decreased densities of aquatic invertebrate drift, but increased densities of terrestrial invertebrate drift in the small tributaries of the Torpy River.  These results correlate with openness of the riparian zone, with the ranking of the effects being 10 m foliated < 10 m defoliated < clear-cut streams.  These results have important implications for the productivity of streams, and for the transfer of energy to higher trophic levels (e.g., fish).

Mean invertebrate drift density for control sites (n=3), 10 m foliated reserve zones (n=3), 10 m defoliated reserve zones (n=3), and clear-cut sites (n=4). Error bars = standard error; coefficient of variation (%) above columns.

(C) Stream Hydraulic Habitats

• Both near-bed hydraulics and substrate composition affect the hydraulic habitats of primary producers in forest streams.  The trend is for greater productivity with flatter, less variable substrates, and for increasing production downstream.  Thus it would appear that as the flow becomes more chaotic (i.e., less embedded, more isolated substrates emergent into the water column), the productivity is reduced.

Average and standard error for relative chlorophyll a (normalized by box mean) data by substrate type.
 
• In streams with 20 m riparian reserves, there appears to be an increase in the relative embeddedness of substrates due to changes in stream capacity through time. We would predict from our substrate experiments that this would lead to more productivity.  The significance of this is that there is an overall change to substrate composition and stream productivity when forest harvesting is introduced to stream ecosystems.

• With respect to benthic consumers, turbulence seems to influence the distribution of larval Epeorus to the greatest extent, even though boundary layers are thin, and nymphs are exposed to high, often near-mean velocities.

(D) Riparian Reserves

• The results of this study indicate that, in general streams with riparian reserves have experienced forestry impacts (i.e., are different) that distinguish them from streams that have not been affected by forestry practices.

•  In the short term, streams with riparian reserves tend to be intermediate between unlogged streams and clear-cut streams so some degree of mitigation has occurred.  Unfortunately, the quality of the riaprian reserve as well of the quantity must be considered in order to provide the most effective mitigation in the short term.

• In the long term, changes to stream capacities may result in changes in stream biodiversity and productivity that may important implications for forest and especially aquatic ecosystems.

• The forestry industry should consider these points and re-evaluate the role and examine the efficacy of riparian buffer strips in the mitigation of forest practices.

 

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Last modified on April 25, 2001.