Riparian Buffer Zone
Note that this is still rough! Still need to wordsmith, but contains most content. Ams 4-12-09
What is a Riparian Buffer?
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Riparian – refers to being adjacent to the banks of river, stream, lake, or other body of
water
Buffer – refers to reduction of impact of the adjacent land use
Leading experts (Lowrance, Leonard, and Sherida, 1985) on riparian buffers define them
as follows:
“A complex assemblage of plants and other organisms in an environment adjacent to water.
Without definitive boundaries, it may include stream banks, floodplain, and wetlands, as well as
sub-irrigated sites forming a transitional zone between upland and aquatic habitat. Mainly linear
in shape and extent, they are characterized by laterally flowing water that rises and falls at least
once within a growing season.”
Cropland Riparian Buffer
Source: http://www.na.fs.fed.us/spfo/pubs/n_resource/riparianforests/
Pastureland Riparian Buffer
Source: http://www.na.fs.fed.us/spfo/pubs/n_resource/riparianforests/
Urban Riparian Buffer
Source: A MODEL RIPARIAN BUFFER IMPLEMENTATION PLAN
Other Types of Riparian Buffers
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Costal Riparian Buffers
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Benefits of Riparian Buffers
(“ECOLOGICAL FUNCTION”, “ECOSYSTEM SERVICES” AND OTHER FUNCTIONS) (AMY)
Still need to go through Hellmund and make sure I’ve incorporated all critical ecological and ecosystem
services.
Ecological Functions
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The problem: Urbanization and agricultural land use disrupt natural functions of riparian areas.
Goal has typically been to get the water away as quickly as possible. Riparian buffers can help
return the stream to its natural characteristics.
Non point source pollution reduction (NPS)
o Achieved through filtration, uptake,
o Riparian buffer acts as a “sink” for pollution
o Common pollutants are nitrate, phosphorus, and pesticides
o Example: Denitrification – riparian buffer traps nitrogen (from fertilizer?) in the soil;
microbes in soil convert nitrate into nitrogen gas. Excess nitrogen and phosphorous lead
to algal growth, deplete oxygen and kill fish. Excess nitrogen in drinking water is also
problematic.
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Hydrology
o Slow overland flow of water by creating physical obstacles in the form of vegetation.
Fallen trees and branches also slows flow of water in stream.
o Reduces the volume and flow rate in river/stream
o Filtering of soil particles from water before entering water
o Store storm water through infiltration
o Root system provides structure to soil which reduces erosion which protects land and
prevents from adding of sediment into stream. Roots also keep soil porus which
increases absorption.
o Holding of water eventually increases percolation into aquifers.
o Reduction of downstream flooding
Foreman’s other functions are (habitat, source, conduit, filter, but I think I’ll discus these under
Ecosystem Services
Additional Ecosystem Services
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Water Quality
o Through the reduction of NPSP and filtration of sediment
o Shading from trees reduces water temperature, moderates temperature fluctuation
which allows the water to hold oxygen
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Aquatic wildlife & habitat
o Shade from trees reduces water temperature and moderates temperature fluctuation –
good for cold water fisheries. This also allows water to hold oxygen. Both of these
functions help provide better habitat for fish, frogs, salamanders, and various reptiles.
o Habitat is created by downed trees and branchs – pools and rifles in water
o Detritus (define) serves as a food source for important members of the aquatic food
chain.
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Terrestrial wildlife & habitat
o Cover is provided for birds and mammals for cover and nesting
o Vegetation provides food and material sources
o Increased insect population also provides food
o Increased connectivity in riparian corridor allows increased movement
Human perceptual experience: aesthetic, recreation opportunities Etc ( be sure to cover all
areas: “ecological, aesthetic, cultural, and economic”)
o For riparian buffers to be socially accepted, especially in urban areas, they must be
understood as they are not overly goomed and seem overgrown to some.
o Provide opportunities for recreation and aesthetic enjoyment.
o Harvesting of forest products can provide additional income to farmers
o Add more here…
o Pull more from http://www.riparianbuffers.umd.edu/fact/FS774.html
Features of (“ECOLOGICAL STRUCTURE”)
Structure of Riparian Buffers
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It is important for a riparian buffer to be designed to meet the needs of the site
Often described as a 3 zone system or 2 zone system (stream side zone and outer zone) (
PATTERN) –
Example of 3 zone system (put this in a graphic)
o Streambed
 Contains woody debris for habitat and flow disturbance
 Debris is held and processed by aquatic fauna
 Shade provides water cooling
o Zone 1: Undisturbed Forest (Closest to water)
 Mixture of fast growing and slow growing native trees
 Generally no tree removal there for provides woody debris for stream
 Provides shade to stream. In small streams, canopy may closed over stream,
connecting the zone 1s on either side of river.
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o Zone 2: Managed Forest
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Filtration, denitrification, Soil traps phosphorus; Prevents these from entering
stream
Tree growth uses excess nutrients
Requires occasional harvesting to remove nutrients stored in plant growth,
therefore species choice can be selected for timber harvest.
Can be designed for various uses such as recreation and alternative forestry
products
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Zone 3: Runoff Control
 Grasses and forbes
 Disperses the flow of water
 Increased infiltration and water storage
 Requires some management to prevent concentrated water flow
Developed Upland (urban, cropland, pastureland)
 People practice conservation measures
 Farmers utilize Best Management Practices for agriculture production and
livestock management: Sediments and pesticides are managed
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Insert pictures gain from initial examples that show pics mapped to zones.
Plant species composition
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Pull specific plant recommendations from here:
http://www.sustland.umn.edu/design/water4.html
WHAT IS THE “VERTICAL AND HORIZONTAL STRATIFICATION”?
Table 1. Relative effectiveness of different vegetation types for specific benefits*
Vegetation Type
Benefit
Grass
Shrub
Tree
Stabilize bank erosion
Low/Medium Medium/High
High
Filter sediment
High
Low/Medium
High
Filter nutrients, pesticides, microbes: sediment bound
High
Low/Medium
High
Medium
Low
Medium
Aquatic habitat
Low
Medium
High
Wildlife habitat: range/pasture
High
Medium
Low
Wildlife habitat: forest wildlife
Low
Medium
High
Medium
Low/Medium
High
Low
Medium
High
Filter nutrients, pesticides, microbes: soluble
Economic products
Visual diversity
Flood protection
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Low
Medium
High
* Source: Adapted from Agroforestry Notes. AF Note-4, Jan 1997. U.S. Department of
Agriculture Forest Service/NRCS. (Amy pulled from
http://www.riparianbuffers.umd.edu/fact/FS733.html
How to design – Not one size fits all (Amy has some stuff for this, not sure how extensive
this needs to be)
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“At least 50 ft in width with dense deep-rooting perennial vegetation with upright growth
patterns (USDA 2000 from Wagner article). However, features will require additional width:
include steep slope, proximity to water pollution hazard, adjacent wetland
“Many factors including slope, soil type, adjacent land uses, floodplain, vegetation type, and
watershed condition influence what can be planted. “
“The function of the buffer, that is, the reason for installing a riparian buffer, should be the
overriding criteria, with other factors (such as those listed above) influencing the final decision
to a lesser degree”
Must determine and communicate to local residents what activities that are permitted or
restricted in riparian zone. Activities may need to be prohibited to protect water quality.
Activities to consider are foot trails, biking paths, thinning of timber resources, construction of
temporary structures, motorized use, presence of pets and livestock, use of pesticide or
fertilizer. Decisions will be site specific.
Barriers and important considerations and other things to find a home
for in presentation
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Human acceptance
Land acquisition (availability and cost)
Landowner needs must be taken into consideration as they will provide maintenance
If your forested area is not as wide as it needs to be, try to compensate by providing denser
vegetation.
In urban areas, human activity can trample and damage vegetation. Planning for human use is
important, and monitoring for and mitigating damage critical.
In urban areas, sediment that washes off streets and other paved areas is likely to have adsorbed
(attracted) heavy metals and hydrocarbon pollutants
Runoff from urban areas also typically carries significant amounts of nutrients-phosphorous and
nitrogen from lawn application of fertilizer and from pet and other animal waste
Riparian buffers should be used in conjunction with sound land management systems away from
the riparian zone. Riparian buffer cannot do it all.
References
Wagner, M. (2008). Acceptance by Knowing? The Social Context of Urban Riparian Buffers as a
Stormwater Best Management Practice. Society and Natural Resources, 21(10), 908-920.
Riparian Buffer Systems- Wye Research and Education Center-- University of Maryland. (n.d.). .
Retrieved April 20, 2009, from http://www.riparianbuffers.umd.edu/.
A MODEL RIPARIAN BUFFER IMPLEMENTATION PLAN: Developed for local units of
government in the Upper Peninsula of Michigan with an emphasis on protecting water quality
and quality of life. (n.d.). . Retrieved April 20, 2009, from
http://www.riparianbuffers.org/dl_implementation_guide.pdf.
Hellmund, P. C., & Smith, D. S. (2006). Designing greenways: sustainable landscapes for nature and
people. Island Press.