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Return to the: DNR Homepage or Type 5 Stream Literature Review (main DNR site)
What
are options for protecting Type 5 stream functions within the scope of
the riparian management strategy?
Statements within this literature review are based on the reported findings from various published sources. Due to differences in sample design, methodology, geographical location, site characteristics, data analysis and interpretation, these statements may or may not agree with the results of other published reports. Despite contradictory results, one cannot say the findings of one author are more or less valid than another, due to the wide range of site characterists. Readers are urged to consider how and where information was collected when interpreting the value of the following conclusions. Headwater stream science is, in many ways, a relatively new field. Early observations and case studies may or may not represent widespread relationships.
Click on the citation following each statement to view the annotated bibliography
- Terrestrial invertebrates
play a vital role in aquatic food supplies, therefore adequate retention
of riparian zones is an important consideration for streamside management.
(Allan
et al. 2003).
- Timber harvesting
signicantly increases marsh temperatures. However, timber harvesting
did not affect spring temperatures. (Black
2001).
- Even when buffers
are in place, stream microclimate gradients can be affected up to
180m away from harvest activities. (Brosofske
et al. 1997).
- Microclimatic change
have been shown to occur in small streams, even when the harvest unit
is far away from the stream but within the same watershed. (Brosofske
et al. 1997).
- Harvesting practices
that include the installation of buffer zones, can still affect nearstream
habitat by increasing temperatures and decreasing humidity levels.
(Brosofske
et al. 1997).
- Slash left in first
order streams restricts the movement of coarse sediment. The author
suggests that leaving slash in first order channels is beneficial
because it reduces the risk of large sediment transportation (generated
from harvest areas) to downstream channels. (Commandeur
et al. 1997).
- Broader buffer widths
(greater than 30m) resulted in similar litterfall rates, as in the
control sites. The author found a linear association between litterfall,
and buffer width. However there was no strong correlation due to the
small sample size. (Grady
2001).
- Buffer windthrow
increased large woody debris (LWD) recruitment into the stream channel
by an average of 33%. (Grizzel
and Wolff 998).
- The buffered streams
warmed faster, but remained cooler than the controls. The author speculates
that the warm air generated from the clearcut area was drifting through
the riparian buffer strip, increasing air temperature. (Hagan
2000).
- Mature shrub species, such as vine maple and huckleberry, should be treated as legacies, and therefore protected during thinning operations because they provide a large seed bank for regeneration, and are a critical food source for wildlife. (Harrington
et al. 2002).
- Leave tree islands
should also be "no-entry" zones to prevent ground disturbance,
and to reduce the expansion of invasive species. (Harrington
et al. 2002).
- Post treatment response
can be assessed more accurately if pretreatment data is used in the
analyses. (Harrington
et al. 2002).
- This author's simple
and inexpensive "sunpath" technique gave superior results
for predicting height growth, in comparison to more specialized equipment
and/or software. (Harrington
et al. 2002).
- The authors state
that their model compares the relationship of the size of large woody
debris relative to stream size, and also has a lower rate of error
than a similar model used by the Washington Department of Natural
Resources. (Hyatt
et al. 2004).
- The un-buffered stream did not exhibit a change in temperature because the logging debris covered and shaded the stream. (Jackson
et al. 2001).
- The headwater streams
that were buffered protected the streambanks from instablity, resulting
in no bank failure, or erosion. However, these buffers did experience
significant blowdown. (Jackson
et al. 2001).
- When small streams
are buffered, Dicamptodon tenebrosus behaves similarly to
those found in uncut areas. This study found that without a buffer,
this species ability to find food and to reproduce, is limited by
its reduced range of movement. (Johnston
and Frid 2002).
- 100m buffers protect
ambient temperatures, humidity, light intensity, and soil moisture.
(Kelsey
and West 2001).
- 150-185m buffers
protect interior buffers from windthrow. (Kelsey
and West 2001).
- 10m buffers (without
the threat of windthrow) are adequate for protecting amphibians and
other wildlife associated with early seral forests. (Kelsey
and West 2001).
- Some options for
protecting buffers from windthrow include: topping trees on the outter
edge--while retaining 6-8m of trunk for snags and future woody debris
recruitment, and/or whorl-pruning trees to break up wind currents.
(Kelsey
and West 2001).
- Careful manuevering
of skidders and logging equipment, can greatly decrease the amount
of stream sediment loading. The operator should follow topographical
contours, and stay out of muddy wet areas (including stream banks).
However, this study found that in the diameter selection harvest,
where 50% of the canopy was removed and equipment was used right up
to the streambank, no statistical increases in sediment were found.
(Kreutzweiser
et al. 2001).
- The basin size for
the perennial initiation point (PIP) sites ranged from 2 to 4096 acres,
and the spatially intermittent initiation point (SIIP) ranged from
2 to 346 acres. The 52 acre default basin size overpredicts the PIP
sites by an average of 744 feet. When PIP, and SIIP data is combined,
it overpredicts by 514 feet. (Liquori
2001).
- There are four main
classes of perennial initiation point (PIP), and spatially intermittent
initiation point (SIIP) sites. They are as follows: mainstem, confluent,
variable source, and stationary. This study found a wide range in
variablity between these four groupings. (Liquori
2001).
- Heavy road traffic
can increase sediment yields by 1,000 times the sediment generated
from abandoned roads, or 130 times that of a road only used by light
vehicles. Sediment discharge from road use, can be averted by gating
roads and abandoning them after timber harvest. (MacDonald
and Ritland 1989).
- Roads and skid trail
placement should not disrupt the pre-existing drainage network. Skid
trails should especially not be in close proximity to the stream channel.
(MacDonald
and Ritland 1989).
- Instream large woody
debris plays an integral role in sediment storage in headwater streams.
Functional woody debris acts as a buffering process to downstream
sediment loading. (MacDonald
and Ritland 1989).
- Variable retention
(ie. riparian thinning) of buffers is one way to satisfy both ecological
and economical interests. (MacDonald
et al. 2003).
- Aspect and topographical features are important factors to consider when making management decisions because they greatly influence temperature. For example, south facing aspects are warmer and dryer than north facing aspects. Furthermore, deeply incised channels may recieve enough shading from their corresponding slopes to regulate temperatures. (MacDonald
et al. 2003).
- The authors conclude
that after 11-15 years, partial harvesting only has a small effect
on stream temperature, chemistry, and turbidity. (Murray
et al. 2000).
- Habitat recovery options: Protection--preserve intact and functional riparian zones by restricting anthropogenic activities that would alter the site. Passive restoration--eliminate human activities and let area re-generate naturally. Active restoration--using management activities to speed up regeneration (ie. planting native vegetation). Rehabilitation--reestablish riparian ecosystems to function optimally despite irreversible damage (ie. hydro dams). Substitution--enhancing and increasing selected riparian functions or mitigation to improve or create habitat off site. (Naiman
et al. 2000).
- FEMAT cites studies
that indicate buffers between 30-185m wide are effective for wildlife
protection. (O'Laughlin and Belt 1995).
- Buffers should be
wider on steep slopes, and in areas were ground infiltration is slow.
(O'Laughlin and Belt 1995).
- Leave trees can help in retaining biodiversity, especially of lichens and bryophytes. (Olson et al. 2000).
- This paper provides
practical resolutions to management decisions that need to consider
a variety of forest uses including commercial, recreational, and endangered
species habitat. (Olson
et al. 2002).
- Narrow buffer treatments
did not maintain the pre-harvest bird communities, however wide buffers
did maintain most of the pre-harvest communities two years after treatment.
(Pearson
and Manuwal 2001).
- Rhyacotriton
kezeri (Columbia Torrent) species prefer high gradient streams
with basalt bedrocks, rather than low gradient streams with marine
sediments. Therefore, harvesting near high gradient streams is more
likely to negatively affect R. kezeri, than logging near
low gradient streams. (Russell
et al. 2004).
- Conservation of riparian
and upland habitats is important for more mobile species that utilize
resources in both zones. (Sabo et al. 2005)
- Forestry management
designed to establish and/or protect overstory canopies and large
woody debris, will positively benefit amphibian species. By modifying
management procedures, riparian obligate species can thrive in buffer
zones and patch reserve areas. (Sheridan
and Olson 2003).
- Adequate riparian
buffers will ensure long term recruitment of woody debris, which is
important for creating a diversified habitat within the stream channel.
(Swanson
and Fredriksen 1982).
- Excessive sediment
loading can be avoided by predeterming erosion-prone sites; by calculating
the erosion rate of management activities; by theorizing downstream
effects of debris flows; and by planning mitigation activities to
offset increased sediment inputs. (Swanson
et al. 1987).
- For differentiating
between Type 4 and 5 streams, within the Skagit basin, a 21 acre default
would be more accurate than a 54 acre default. (Veldhuisen
2000).
- This study suggests
that in the Skagit basin, a 3 acre default should be considered for
streams with glacial-lacustrine sediment deposits. (Veldhuisen
2000).
- Habitat connectivity between streams and within a watershed is important for maintaining Ascaphus truei dispersal and gene flow. (Wahbe et al. 2004).
- Maintaining detritus
loading to small streams is integral for the conservation of diversified
food webs. (Wallace
et al. 1997).
- This study suggests
that a "patch retention management strategy" could greatly
reduce extirpation by leaving suitable habitat remnants. (Whitman
and Hagan 2000).
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