Week 13 - 19 Nov. 2013 Forestry measurements

Outdoor lab:  Forest measurements in three types of 10 x 10 m plots

Monoculture

Mature forest

Disturbed area

Which will have most tree species?

Which will have most biomass?

 

Densiometer - The densiometer is a mirrored device to measure the amount of shade provided by the forest canopy.

Instructions

1.      At the proper location in your plot, face north and hold the densiometer 0.3 m (1 ft) above the ground.  Level the densiometer using the bubble level.  Move the densiometer in front of you so your face is just out of the mirror.

2.      Count the number of squares shaded by trees, leaves, branches etc.  Record the value (0 – 24) in the proper line of your form.

3.      Repeat at the same location facing east, south, and west.  Record the values.

4.      Move to the next location in your plot, and repeat Steps 1 - 3.

5.      Follow your field form to average the values for each location, and multiply the final values by 4.16 to determine percent canopy cover at each location in your plot.

Practice – Determine the percent canopy cover in each illustration. 

A.

B.

                         # of shaded squares = 6 x 4.16 = 25% canopy cover

                             # of shaded squares = ____ x 4.16 = _____ %

Diameter at breast height (DBH) – Tree trunk diameter at breast height which is 4.5 feet above ground level.  Slight adjustments are needed for trees growing on a slope, or for those that lean, fork low down, or have misshapen trunks.  You can measure the circumference and convert to diameter using:

diameter = circumference ÷ π               where π (Pi) is a constant (3.14)

So, to find the tree diameter you simply divide your circumference by 3.14

Instructions

1.      Choose a tree to measure that is at least 7 cm in diameter at breast height (4.5 feet off the ground).

2.      Use the measuring tape to measure in centimeters the circumference of this tree at 4.5 feet above the ground.

3.      Record this number and the tree species on your field form.

4.      Repeat for the remainder of trees in your plot.

5.      Follow instructions on your field form to determine largest, smallest, average tree diameters, etc.

Adapted from Royal Forestry Society http://www.rfs.org.uk/learning/measuring-trees (accessed 18 Nov. 2013)