Attachment “2”
An Assessment of Riparian Vegetation in a Human-Influenced Landscape
Curriculum created by Lisa Carlson, CentraliaCollege
Student Handout
Riparian Forest Data Instructions
Lay out transect
Using a 30 meter tape measure, lay out a transect by placing 0m at the river’s edge, and walking in a straight line away from the river. Sampling node will be established at 10m, 20m, and 30m, with each group doing the data collection at one of the nodes.
Tree density and diameter
Use special tape measures, in units of centimeters times pi (3.14), thus if you measure circumference, the result is diameter (since C = πd). The pink string is 5 meters long, knot to knot. Have one person hold the string at the node, and another bring the string to each tree around the circle. If the tree’s center is within the 5m, then measure its DBH. Wrap the D-tape around the tree at 1.4 m (4.5 ft) above ground level (this is breast height). For those trees at least 3cm, enter the DBH of each within 5m of sample node in the blank according to its species.
Tree density may be calculated by taking the total number of trees at a sample node, and dividing by the area sampled. A = πr2, so 3.14 x 5m2 = 78.5m2. Thus, if you have 14 trees at a node, tree density is 14 trees / 78.5 m2 = 0.18 trees per m2.
Forest Canopy Density
At each sampling location you should hold the spherical densitometer (curved mirror with a grid) level in front of you above the sample node (about waist height). Count and record the number of corners which have open sky. Multiply the total number of open corners by 1.04. This is the percentage of open sky. To determine the canopy cover, subtract the percentage of open sky from 100%.
Maximum Canopy Height
One measurement is sufficient for the entire site, rather than for each node. Choose tallest tree at the site with good visibility to its top. Site the top with a clinometer and read the percent column. Multiply percent by distance to base of tree, measured with tape measure. Add height to eye of person with clinometer, or do a second triangle to base of tree if on a slope.
Non-native ground cover
Estimate the percent of the ground covered by non-native plant species up to 1m high within 5m of sample node. Common non-native species include Himalayan blackberries, and many members of the pea and aster families. Ask your instructor for help identifying these species.
Shrub Density
One person stands at the sample node holding the 5 meter pink string and a paper tube (toilet paper tube, paper towel, or rolled up paper). Another person stands at the other end of the string, at each of the cardinal directions (north, east, south, west). The person at the center should hold the tube to her/his eye and estimate the percentage of the other person covered by shrubs. Record this number for each direction, then take the average.
Light levels
Using a light meter, take readings standing at each node at each of the cardinal directions (north, east, south, west). Average the four readings for each node.
Temperature
Take one reading at each node with temperature sensor.
Relative humidity
Take one reading at each node with humidity sensor.
Equipment needs: 30m tape, 3 diameter tapes, 3 pink 5m strings, spherical densimeter, clinometer, sensors for light, temp, humidity.