LOGGING IN RIPARIAN ZONES
Logging in Riparian Zones during winter and the reduction of soil disturbance
Matthew Chapin
Geology 335
University of Idaho
Spring 2011
(Arial photograph: Logging within close proximity to a Riparian zone in Alaska. Taken from,
http://brettcole.photoshelter.com/gallery-image/Logging/G0000.4gE7UrmsW0/I0000aC2feUS7KQI ).
Abstract
Vast amounts of lumber are located on the crossing point between land and fluvial
systems. These areas are called Riparian zones. Riparian zones are generally restricted to lumber
harvesting because of soil disturbance, water quality conditions, and wildlife habitat reduction;
however, recent studies may have a new procedure to harvest without disturbing soil, and
causing further erosional effects.
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Riparian zones are important biofilters that protect fluvial environments from
unwarranted sedimentation and erosion. They also control and influence transmits of nutrients
and sediments between fluvial and terrestrial systems (Phillips, Swift, and Blinn 273-286). These
zones reduce stream energy by increasing vegetation and root structures, which in turn reduces
erosion, as well as promoting bank stability. These zones are also important wildlife habitats that
contain an abundant diversity of flora and fauna. Bearing in mind the importance of riparian
zones, they are often restricted from logging which involves removing vegetation from the
earth’s surface. Logging often leads to disturbances in soil, and increases erosional forces. One
of the major causes of erosion from logging riparian zones is from building roads for logging
transportation. Roads are built to follow the easiest flattest path; in addition, streams do the
same. To build logging roads streamside vegetation is often removed consequently increasing
erosional forces, and negatively affecting water quality as well as many other attributes.
The greater part of water quality, stream habitat, and other riparian zone roles occurs
adjacent to the stream and is reduced in distance from the stream. Trees and vegetation in the
vicinity of the water provide shade, support bank stability, increase wildlife habitat, and many
other functions (Phillips, Swift, and Blinn 273-286). When harvesting, tree orientation is
essential for the most beneficial practices. Trees that lean away from the stream are most
preferred because they provide less aquatic habitat (Phillips, Swift, and Blinn 273-286). Better
practices for harvesting are those that reduce soil disruption, exclude pollution from logging, and
minimize habitat intrusion.
The Journal of Forest Operations Review released an article in February 2011, stating
that lumber can be harvested from riparian zones during the winter without agitating the soil.
The frozen ground and snow help minimize soil disturbance. The Canadian company
FPInnovations conducted two trials of harvesting riparian zones during the winter. Both trials
that were conducted concluded that harvesting riparian zones in the winter protects soil,
preserves water quality, and decreases erosion. On the other hand harvesting productivity was
lower because of increased travel time, stem damage, and increased productivity costs. Both
trials conducted by FPInnovations were within a certain distance from the actual bank, which
would also sustain bank stability; however, the trials conducted have no information regarding
the future effects of harvesting this area. Before assuring that harvesting riparian zones during
the winter protects soil and water quality, continual studies need to be conducted on the future
environmental effects.
Logging in riparian zones is an important geomorphic process, being that it increases
erosion, reduces water quality, and affects many other fluvial features. Increasing unwanted
sediment into streams may result in a number of things including; elevate the stream because the
channel becomes filled with sediment which increases stream velocity and slope, produce
changes in the stream flow by depositing unwanted sediment in areas of lower velocity,
disengage the stream from its equilibrium, and many other effects (Easterbrook, 117-132). The
geomorphic processes that result from logging these areas are often devastating; therefore, the
best management practices are to avoid removing streamside vegetation.
Overall, fluvial mechanics may or may not be inversely affected by logging riparian
zones depending on the season of harvest. Additionally, further studies need to be conducted on
the future outcome of logging these areas during winter to assure that these practices do not lead
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to unwanted environmental affects. The reduction of soil disturbance from frozen ground and
snow may sound like a positive result; however, prolonged studies have not been conducted
which may make FPInnovations conclusions invalid.
(Post logging adjacent to a Riparian zone in Alaska. Taken from, http://brettcole.photoshelter.com/galleryimage/Logging/G0000.4gE7UrmsW0/I0000838o47KoEVY ).
References
Easterbrook, Don J. Surface Processes and Land forms. 2nd ed. New Jersey: Prentice Hall inc., 1999. 117-132. Print.
"Mechanical Harvesting in Riparian Zones in Winter." Forest Operations Review. 13.1
(2011): 30. Print.
Phillips, Michael J., Lloyd W. Swift, and Charles R. Blinn. "Best Management Prac tices for
Riparian Areas." 273 -286. Web. 26 Mar 2011.
<http://coweeta.uga.edu/publications/31.pdf>.