
Riparian Zone Habitat Assessment Vegetation and More
What is “riparian vegetation”? • Plants growing on the streambank and adjoining floodplain • Plants in this area are influenced by the water from the stream
Riparian Vegetation Functions • Roots stabilize banks / reduce erosion • Provide structure or cover for fish • Taller vegetation provides shade • Organic food source for aquatic organisms • Leaves • Terrestrial insects
Riparian Vegetation Functions • Pollutant filtering • Fall into stream – large woody debris • Shapes channel • Substrate for biological activity
Relationship to Water Quality • Turbidity / Sediment • Phosphorus • Temperature (Shade) • Nutrient Uptake • Nutrient Release (Alder)
Plant Presence Habitat Quality Actual Diversity Invasive Species Changes over time Riparian Assessment Stability Shade Invasive Species Large Wood Recruitment Considers non-vegetative stable substrates Two Ways to Assess a Riparian Zone
Riparian Assessment • Can be broken into 3 sections: • a 100’ riparian transect perpendicular to the stream, • a 100’ “greenline” transect along the stream, • a riparian tree count performed in a 100 sq ft area along the stream
Riparian Transect 100ft X 10ft Zone 3 Zone 2 Zone 1 FLOW Greenline Transect 100ft X 5 ft Riffle Gravel bar Pool Starting point
Riparian Assessment • Total area = 100 ft x 100 ft (30 m2) • Instructions in feet and meters • Starting point is at beginning of first (downstream) habitat unit
Zone 3 Zone 2 Zone 1 FLOW Riffle Gravel bar Pool Riparian Transect Each zone is 10 meters (33 feet) long Total transect length = 30 meters (100 feet)
Riparian Transect Width 10 feet STREAM Estimate % cover by 10-20 % increments May have more or less than 100 feet of “riparian zone” Length 11 feet
Johnson Creek 175 ft
Measure Slope Zone 2 Zone 3 Zone 1 Zone 2 Zone 1 10° 25° 40° 5° 55°
Greenline Transect GREENLINE – the first strip of vegetation along the stream STREAM Length 11 feet Width 5 feet
Zone 3 Zone 2 Zone 1 FLOW Riffle Gravel bar Pool Riparian Tree Count Conifer Deciduous
Tree Size Class Circumference Diameter = Circumference (approx. 3.14) Diameter
What Does it Tell Us? • Riparian and Greenline Transects • Extent and diversity of riparian zone • Stability • Invasive species • Riparian Tree Count • Age-class diversity • Large woody debris recruitment (old growth conifer, >35”, is MOST desirable)
Evaluation of recruitment • How many trees of varying size are present in the riparian zone? • How close/far are they from the water? • Over what time period might they become available?