Riparian Areas: Functions and Conditions

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Riparian Areas Functions and Conditions
Authors Gene Surber, MSU Extension Natural
Resources Specialist Bob Ehrhart, Research
Specialist, RWRP, Univ. of Montana
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Riparian Areas

• Wetlands
• Riparian areas
• Overflow areas
• Wet meadows
• Marshes
• Sloughs

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Characteristics of Riparian Areas

• Green Zone link between aquatic and
  terrestrial
• Water
• Landform
• Soil
• Vegetation

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Riparian Areas

• More dynamic than uplands
• Flooding
• Deposition of sediment
• Accumulation of organic matter
• Dewatering
• Changes in location

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Functions of Riparian Areas

1. water storage
2. flow energy dissipation
3. water quality
4. sediment trapping
5. bank building and maintenance
6. primary biotic production

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Store and Release Water

• Soil acts like sponge
• Reduces flooding
• Extends time that surface water is available

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Dissipate Energy of Flowing Water

• Slows water
• Vegetation
• Woody debris
• Large boulders
• Cobbles

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Provide Water Quality

• Natural pollution control

Trap sediments (nutrients, pesticides, toxic
metals, bacteria)
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Trap sediments

• Trap sediments development of new streambanks
  and bars

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Protect soil and water

• Shields soil and water from
• Wind
• Sunlight
• Rain drop impacts

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Enhances Productivity

• Most productive parts of a landscape

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Provide wildlife habitat

• Water, food, cover and travel routes
• Birds
• Mammals
• Insects
• Fish

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Evaluating the Health of Riparian Areas

• How well the riparian area carries out the
  functions
• Physical
• Biological

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Evaluating Physical Features

• Channel downcutting
• Channel widening
• Amount, location, causes bare ground
• Amount of fine materials
• Amount of rock

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Downcutting

• Incisement erodes away the channel bottom

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Channel becoming wider shallower

• Banks break down
• Stream becomes shallower
• Stream temperatures rise

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Amount, location, causes of bare ground

• Bare ground erosion
• Noxious weeds
• Compaction or bank shearing

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Amount of fine materials on channel bottom

• Silts, clays, decomposing organic material
• Not enough water running

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Bank Rock Content

• Large rock versus
• Sand, silt, small gravel
• Management considerations

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Biological Features

• Types amounts of plants
• How well they fulfill functions
• Amount of foraging browsing
• Mix of age classes of wood species

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Streambank protection

• Vegetation
• Slows velocity
• Stabilizes streambanks
• Reduces erosion

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Amount Types of Vegetation

• Canopy cover of desired plants
• Noxious weeds

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Presence of Trees and Shrubs

• Woody plants (trees shrubs)
• Bank stabilizers
• Food cover
• Determining appropriate presence

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Woody species age class

• Distribution of age class
• All old trees
• All young trees

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Degree of Browsing

• Excessive use
• (50 of current or previous years growth)

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Woody Draws

• Perform functions of riparian areas
• Habitat
• Cover, food, water
• Grazing management plan