Riparian Areas: Functions and Conditions Authors: Gene Surber, MSU Extension Natural Resources Specialist Bob Ehrhart, Research Specialist, RWRP, Univ. of Montana Riparian Areas Wetlands Riparian areas Overflow areas Wet meadows Marshes Sloughs Characteristics of Riparian Areas “Green Zone” – link between aquatic and terrestrial Water Landform Soil Vegetation Riparian Areas More dynamic than uplands Flooding Deposition of sediment Accumulation of organic matter Dewatering Changes in location 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 Store and Release Water Soil – acts like sponge Reduces flooding Extends time that surface water is available Dissipate Energy of Flowing Water Slows water Vegetation Woody debris Large boulders Cobbles Provide Water Quality Natural pollution control Trap sediments (nutrients, pesticides, toxic metals, bacteria) Trap sediments Trap sediments – development of new streambanks and bars Protect soil and water Shields soil and water from: Wind Sunlight Rain drop impacts Enhances Productivity Most productive parts of a landscape Provide wildlife habitat Water, food, cover and travel routes Birds Mammals Insects Fish Evaluating the Health of Riparian Areas How well the riparian area carries out the functions Physical Biological Evaluating Physical Features Channel downcutting Channel widening Amount, location, & causes bare ground Amount of fine materials Amount of rock Downcutting “Incisement” = erodes away the channel bottom Channel becoming wider & shallower Banks break down Stream becomes shallower Stream temperatures rise Amount, location, & causes of bare ground Bare ground – erosion Noxious weeds Compaction or bank shearing Amount of fine materials on channel bottom Silts, clays, decomposing organic material Not enough water running Bank Rock Content Large rock versus Sand, silt, small gravel Management considerations Biological Features Types & amounts of plants How well they fulfill functions Amount of foraging & browsing Mix of age classes of wood species Streambank protection Vegetation Slows velocity Stabilizes streambanks Reduces erosion Amount & Types of Vegetation Canopy cover of desired plants Noxious weeds Presence of Trees and Shrubs Woody plants (trees & shrubs) Bank stabilizers Food & cover Determining appropriate presence Woody species age class Distribution of age class All old trees All young trees Degree of Browsing Excessive use (50% of current or previous year’s growth) Woody Draws Perform functions of riparian areas Habitat Cover, food, water Grazing management plan