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Scientific Literature Review of Forest Management Effects on

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					                   Scientific Literature Review of
                   Forest Management Effects on
                           Riparian Functions for
                          Anadromous Salmonids

Mike Liquori
Dr. Doug Martin
Dr. Robert Coats
Dr. Lee Benda
Dr. David Ganz
                                           October 7, 2008
                         Outline

• Project Approach
• Key Findings
• Synthesis
• Policy Inferences
• Process Critique
• Next Steps




                      October 7, 2008
                        Our Team

• Mike Liquori
• Dr. Doug Martin
• Dr. Robert Coats
• Dr. Lee Benda
• Dr. David Ganz
• Ms. Shelby Sheehan




                       October 7, 2008
                                  Project Approach

• Reviewed Assigned Literature
  – TAC Primer
  – Peer-Reviewed Literature

• Addressed Key Questions
  – Collaborative & Integrated

• 2-Day Synthesis Workshop
• TAC Review
  – Responded to extensive comments




                                        October 7, 2008
General Themes




        October 7, 2008
                                    General Themes

1. Spatial context is important, as it influences
   functional response patterns.


2. Longitudinal controls on exchange functions
   AND lateral controls are important in
   maintaining the watershed-scale ecosystem
   structure that maintains aquatic habitats.




                                          October 7, 2008
                                  General Themes

3. Disturbances are an important mechanism for
   establishing conditions that support riparian
   functions
  –   Stand structure
  –   Vegetative succession
  –   Wood recruitment
  –   Nutrient exchange
  –   Thermal regulation




                                        October 7, 2008
                                   General Themes

4. Riparian zones can buffer a stream from
   direct management impacts, and they alter
   the disturbance regimes in ways that can
   affect both short-term and long-term
   evolution of riparian areas.


5. There are dynamic interactions among and
   between riparian exchange functions that
   alter the importance of exchange functions for
   any particular setting.

                                        October 7, 2008
                                      General Themes

6. Active and strategic riparian management can
   limit risks and benefit salmonids
  –   temperature regimes
  –   ecological productivity
  –   woody debris recruitment
  – fuel loads and other disturbance risks
  –   etc




                                             October 7, 2008
                                    General Themes

7. There are variations in the buffer width
   necessary to meet each function, and these
   variations depend on several factors


8. The reviewed literature offers many opinions,
   but limited hard data to evaluate the scientific
   effectiveness of any approach




                                          October 7, 2008
                                          General Themes

9. Risks and benefits are inherently value
   judgments best determined by policy

  –   Science can only provide the context



10. The geographic and watershed-scale variables
    for buffers requires a policy framework

  –   Information in the literature is available, but
      inconclusive in the absence of a framework


                                                 October 7, 2008
Biotic & Nutrient
        Exchange




           October 7, 2008
                    Key Findings – Biotic & Nutrient

• Riparian leaf litter is an important food source




                                          October 7, 2008
                     Key Findings – Biotic & Nutrient

• Litter quantity & quality is important

  – Highest: alder

  – Moderate: maple, willow and cottonwood

  – Low: conifers and oaks




                                             October 7, 2008
Key Findings – Biotic & Nutrient


      • Opening the
        canopy cover
        over some
        streams
        increases
        ecological
        productivity



                     October 7, 2008
                         Key Findings – Biotic & Nutrient

• Tradeoffs between nutrient exchange and other
  functions

  – Heat regulation

  – Water – response to flooding

  – Wood recruitment potential




                                              October 7, 2008
                Key Findings – Biotic & Nutrient


A 100 foot wide
no-cut buffer on
both sides of a
stream provides
conditions similar
to a “no harvest”
level



                                     October 7, 2008
                    Key Findings – Biotic & Nutrient

• No-cut buffers may forego
  opportunities to:

  – increase fish growth rate and
    biomass

  – manage other functions




                                         October 7, 2008
Heat Exchange Functions




                 October 7, 2008
                                Key Findings – Heat

• Stream temperatures affect the growth and
  mortality of salmonids

  – Too COOL: insufficient growth & lower ocean
    survival

  – Too HOT: lower abundance & risk of mortality




                                          October 7, 2008
                                Key Findings – Heat

• Riparian shade helps to control heat input to
  streams
• Other factors important too




                                         October 7, 2008
                                   Key Findings – Heat

• No single, fixed-width buffer or canopy closure
  prescription can regulate heat objectives for
  salmon in all cases.
• Effective shading can be provided by:

  – Lateral: buffer widths ranging from 30 to 100 ft

  – Longitudinal: generally within 500 to 650 ft
    upstream




                                              October 7, 2008
                              Key Findings – Heat

• Water temperature protection could be
  provided by varying the riparian shade
  requirements in relation to stream temperature
  sensitivity.




                                        October 7, 2008
                                        Key Findings – Heat

• The relative importance and sensitivity of
  riparian vegetation to influence stream
  temperature varies by:

  – Geographic province

  – At least 11 site specific factors



• Stream temperature targets can be helpful in
  managing to desired shade conditions

                                                 October 7, 2008
                               Key Findings – Heat

• Timber harvest in or adjacent to riparian areas
  can influence microclimate,




                HOWEVER

• microclimate changes have not been
  demonstrated to translate to changes in water
  temperature.

                                         October 7, 2008
                               Key Findings – Heat

• Shade conditions inversely influence biotic and
  nutrient exchange functions.


• Similarly, the canopy that provides shade also
  influences:


  – Water exchange functions

  – Wood exchange functions


                                        October 7, 2008
Water Exchange
     Functions




        October 7, 2008
                                   Key Findings – Water

• Forest management activities in riparian areas
  might affect stream functions

  – effect is likely to be small

  – highly variable

  – strongly influenced by the watershed context

  – impacts are mixed



                                             October 7, 2008
                            Key Findings – Water

• Management affects the riparian canopy

  – canopy interception

  – evapotranspiration




                                      October 7, 2008
                                   Key Findings – Water

• There is little direct evidence of riparian effects:

   – studied for entire watersheds
   – riparian zones alone have not been studied



• The most sensitive hydrologic areas may be
  steep, zero-order basins (hollows)

   – This was not a focus of this review



                                              October 7, 2008
                                Key Findings – Water

• Soil compaction in riparian areas can
  negatively affect hydrologic processes.

  – Suggests limits for heavy equipment near streams




                                            October 7, 2008
                                 Key Findings – Water

• Hyporheic flows are important ecologically

  – forest management effects are unclear




                                            October 7, 2008
                                Key Findings – Water

There is very little in the reviewed
literature that can used to directly
address the issue of buffer strip
delineation relevant to the water
function




                                          October 7, 2008
                               Key Findings – Water

• There are probably regional differences

  – Casper Creek (coastal Mendocino County)




                                          October 7, 2008
                                   Key Findings – Water

• Regional differences are likely to reflect:

   – Geology

   – topographic variation

   – dominant runoff mechanisms




                                                October 7, 2008
Wood Exchange Functions




                 October 7, 2008
• Wood functions vary by stream type and
  geomorphic context




                                      October 7, 2008
                                  Key Findings – Wood

• There are three dominant sources of instream
  wood in California second-growth forests

  – bank erosion: ~40-60%

  – streamside landslides: ~30%

  – treefall: ~10-30%




                                           October 7, 2008
Bank    Treefall     Landslides
Erosion      Windthrow




                         October 7, 2008
                                 Key Findings – Wood

• The zone that can contribute 90% of observed
  wood recruitment varies depending on the
  dominant processes

  – Bank erosion: < 30 feet

  – Streamside landsliding: 100-200?? feet

  – Wind: 75-130?? feet

  – Treefall: <100 feet


                                             October 7, 2008
                                 Key Findings – Wood

• The major factors that are reported to influence
  wood recruitment conditions include:
  – Existing Stand Density, Composition And Structure

  – Stream Type, Order and Watershed Context

  – Vegetation Type and Soil/ Site Index

  – Regional Context

  – Disturbance Context


                                            October 7, 2008
October 7, 2008
October 7, 2008
                                   Key Findings – Wood

• Instream wood can move downstream
  through:
  – Flood: in larger streams




  –                            Debris-flow: in steep, low-
      .                                     order streams



                                                October 7, 2008
                                Key Findings – Wood

• Wood recruitment potential depends upon:

  – Existing stand conditions

  – Successional pathway

  – Disturbance Regime




                                         October 7, 2008
                                 Key Findings – Wood

• Forest management appears to influence
  natural disturbance regimes by affecting

  – How often disturbances occur

  – How large the disturbances are

  – Which type of disturbances are likely




                                            October 7, 2008
                                   Key Findings – Wood

• Active forest management can manipulate
  riparian stand structure in ways that:

  – a) affect the growth and mortality dynamics for the
    stand and

  – b) influence the types, qualities and risks of
    disturbances


• and thus influence wood functions


                                                October 7, 2008
Sediment Exchange
        Functions




           October 7, 2008
                          Key Findings – Sediment

• Sediment Best Management Practices (BMPs)
  typically address sediment primarily in three
  general ways:

  – Source controls

  – Runoff Controls

  – Treatment Controls




                                        October 7, 2008
                                Key Findings – Sediment

• Sediment sources from forest management
  include:
  –    surface erosion processes (rills and sheetwash)
  –   skid trails
  –   yarding ruts
  –   gullies
  –   soil piping
  –   roads
  –   fire
  –   mass wasting processes
  –   bank erosion
  –   windthrow
  –   legacy forest management practices
                                                 October 7, 2008
                           Key Findings – Sediment

• Riparian buffers are mostly effective at limiting
  sediment delivery


• In the absence of buffers, ground disturbances
  that are near streams have the potential to
  deliver sediment




                                          October 7, 2008
                               Relevant Report Section




                               2.1.1
                               2.1.2
                               2.1.3
                               2.1.4

                               2.2.1
                               2.2.3
                               2.2.4
                               2.2.5
                               2.1




                               2.2
    Erosion Mechanism                                            Effectiveness of Buffers
Surface Erosion                1 1     1                 1   Effective
Skid Trails and Yarding Ruts   1   1   1   1 1 1    1    1   Effective
Bank Erosion                     1   1 1   1 1 1    1    1   Effective
Windthrow                        1             1         1   Varies
Gullies                        1           1        1    1   Somewhat Effective
Road-Related Sediment          1 1 1       1 1 1    1    1   Somewhat Ineffective
Fire                           1 1     1                 1   Insufficient Information
Mass Wasting                     1            1 1 1      1   Insufficient Information
Soil Piping                    1                             Insufficient Information




                                                                               October 7, 2008
                         Key Findings – Sediment

• Selective forest management within buffers
  does not appear to substantially increase
  sediment production or delivery


• The extent that riparian buffers along
  headwater streams are necessary to prevent
  sediment delivery is not clear from the
  reviewed literature.




                                       October 7, 2008
                             Key Findings – Sediment

• Despite the lack of evidence for direct sediment
  delivery, instream sediment yields tend to
  increase following logging


  – Sources of such sediment are not clear




                                             October 7, 2008
                                                                    Key Findings – Sediment

• Source distance relationships for sediment also
  appear to vary with the dominant processes
  and site Figure 7-1. Sediment Filtration Effectiveness
            conditions Buffer Strips
                         of



                         100%
   Sediment filtration
     effectiveness




                         80%

                         60%

                         40%

                         20%

                           0%
                                0                  50                 100                150                   200

                                                              Buffer width (ft)
                         Castelle (1996)   Ketcheson (1996)    King (1979)    Megahan (1996)   Benoit (1978)




                                                                                               October 7, 2008
                          Key Findings – Sediment

• The reviewed literature did not provide a
  sufficient guidance for the various landscape
  situations in California, although a more
  detailed analysis of data may lead to more
  definitive specifications for buffer width.




                                         October 7, 2008
                           Key Findings – Sediment

• Riparian sediment management objectives
  include mitigating for:

  – Harvest-Related Sediment

  – Hydrologic Link to Sediment Delivery

  – Road Sediment

  – Mass Wasting Impacts



                                           October 7, 2008
Synthesis




   October 7, 2008
• The scientific basis for defining buffer widths
  in fish-bearing streams is based on source
  distance relationships




                                          October 7, 2008
                Challenges with Source Distances

1. The instream biological response to source
   distance relationships has not been
   established.
2. Source distance relationships ignore the
   trade-offs between functions.
3. Source distance relationships downplay the
   importance of the quality of contributed
   inputs.
4. Source distance relationships only capture
   the effects of some disturbances.

                                       October 7, 2008
                Challenges with Source Distances

5. Source distance relationships describe the
   relative contribution, but not the total
   contribution.
6. Source distance relationships ignore
   changes over time.
7. Source distance relationships ignore the
   longitudinal context.




                                          October 7, 2008
                        Longitudinal Variation

• River Continuum v.
  Network Dynamics


• Geomorphic Context
  is Important


• Biological Hotspots




                                   October 7, 2008
October 7, 2008
October 7, 2008
                         Longitudinal Variation

Managing for
longitudinal variation
requires an
understanding of how
different ecosystem
processes act to form
and maintain habitats
throughout the channel
network.




                                    October 7, 2008
                        Key Findings – Synthesis

• The concept of disturbance cascades may
  provide an ecologically and geomorphically
  integrated framework for developing
  management practices guidelines in these
  landscapes.




                                       October 7, 2008
October 7, 2008
                           Key Findings – Synthesis

• Such a framework might benefit by
  considering practices at larger spatial scales
  and longer time scales that recognize the
  recovery rates associated with various
  functional processes




                                           October 7, 2008
October 7, 2008
Policy Inferences




            October 7, 2008
Typical Forest Buffer Widths




                 October 7, 2008
        Typical Forest Buffer Widths


Selective v. No-cut




                         October 7, 2008
    Policy Approaches to Riparian Management

                  Advanced
           Recovery & Enhancement




Riparian
                                Resource
Reserves
                                Optimization

                                     October 7, 2008
                                 Riparian Reserves

• Large, often uniform & continuous buffers


• Driven by buffer width


• Minimize management effects within riparian
  areas


• GOAL: return late-seral characteristics to
  riparian areas over a period of centuries
                                         October 7, 2008
                             Resource Optimization

• Actively design the characteristics of riparian
  forests
• Driven by buffer width, often varied by stream
  type
• Allows flexibility
• Minimize management effects on stream
  functions
• GOAL: maximize benefits while supporting
  other resource objectives

                                          October 7, 2008
                 Advance Recovery & Enhancement

• Actively design the characteristics of riparian
  forests
• Driven by landscape context
• Requires detailed site-specific tools & skills
• Maximize benefits to salmonids
• GOAL: expedite recovery of functional aquatic
  ecosystem dynamics




                                           October 7, 2008
                            Policy Sets the Framework

• Riparian reserves
  – low risk, long recovery period (centuries)



• Active Management
  – higher risk, faster rates of recovery & function
  – Careful design can mitigate increased risk




                                                 October 7, 2008
                     Scientific Basis for Management

• BMPs
• Decision Support                 g
                                 in ses




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                                Basis

                        M ue
• Design Approaches

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                                           October 7, 2008
                  Scientific Basis for Management
               Management Policies,
                Priorities and Goals




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                     Monitoring &
                     Assessment

                                                       October 7, 2008
Process Critique




           October 7, 2008
                                Process Critique
• Level of effort greatly exceeded budget
• Very strong steering - too focused on details
  – Limited ability to focus on policy implications

• Many of the assigned papers were not relevant
• Several topics were not well addressed by
  assigned literature
• TAC steering well-intended but cumbersome




                                               October 7, 2008
                               Process Critique
• Challenges with the Key Questions
  –   Too many questions (64)
  –   Too many sub-questions within questions
  –   Lots of redundancy
  –   Many fringe issues
  –   Too broadly framed
  –   Often ambiguous
  –   Often did not capture the real issue




                                                October 7, 2008
                         Example Key Question

Have forest management activities in riparian
zones for higher order channels with floodplains
and adjacent to small headwater first and second
order channels been shown to alter water transfer
to stream channels, affecting near-stream and
flood prone area functions (e.g., source area
contributions to stormflow, bank instability,
lateral and vertical channel migration, flow
obstruction or diversion of flow)?




                                        October 7, 2008
                         Example Key Question

Have forest management activities in riparian
zones for higher order channels with floodplains
and adjacent to small headwater first and second
order channels been shown to alter water transfer
to stream channels, affecting near-stream and
flood prone area functions (e.g., source area
contributions to stormflow, bank instability,
lateral and vertical channel migration, flow
obstruction or diversion of flow)?




                                        October 7, 2008
              Process Recommendations
• Better focus in developing Key Questions
  – Less redundancy
  – Less ambiguity
  – More clarity & focus

• Allow the consultant team more opportunity to
  influence the scope of work


• More clear focus on desired outcomes



                                         October 7, 2008
Recommended Next Steps




                October 7, 2008
                           Recommended Next Steps

• Lot’s of good detail available from literature

   – Supports specific rule-making elements

   – Support for management decision-support tools
     that incorporate science



• Requires a policy framework to provide
  direction



                                              October 7, 2008
                         Recommended Next Steps

• Establishes value positions regarding various
  management approaches


                                 Advanced
                          Recovery & Enhancement




                      Riparian
                                              Resource
                      Reserves
                                              Optimization



                                               October 7, 2008
                        Recommended Next Steps

• Identify clear functional goals and performance
  measures that define the decision space for
  science-based management


• Outline a planning approach that provides a
  policy-oriented framework (i.e. based in
  regulations, planning processes, etc)




                                        October 7, 2008
                       Recommended Next Steps

• Identify supporting science-based management
  and policy infrastructure (e.g. science
  resources, adaptive management framework,
  etc)
                                       Management Policies,
                                        Priorities and Goals




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                                            Monitoring &
                                            Assessment



                                                               October 7, 2008
                            Recommended Next Steps

• With a policy framework in place, revisit the
  literature to identify specific details

  –   Decision-support tools
  –   Models & mapping capabilities
  –   Resource targets
  –   Riparian management specifications
  –   Design tools
  –   etc




                                           October 7, 2008

				
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