Monitoring the growth, condition, and survival of individual trees or groups
of trees over extended time intervals.
For ground-level plots:
-Suitable record book or data file for keeping photo point information
over many years.
For aerial plots:
- A
Monitoring the growth, condition, and survival of individual trees or groups
of trees over extended time intervals.
For ground-level plots:
-Suitable record book or data file for keeping photo point information
over many years.
For aerial plots:
- A 35 mm camera and color print or slide film are probably the most versatile.
A short focal length lens (about 35 to 70 mm) is preferred. Images from very
wide-angle lenses (shorter focal lengths) may have too much distortion, and
telephoto lenses (longer focal lengths) may not have a wide enough field of
view to be practical.
- Tripod to ensure that serial photographs are taken from the same elevation
and angle. A small bubble level and a protractor attached to the tripod head
can be used to duplicate photo angles more accurately.
- A magnetic compass to align the angle of the camera in the horizontal plane.
- Maps to note the location of the camera and the photo plot.
- Permanent survey markers, although not strictly necessary, may be useful
for marking the exact camera location.
- Aerial photographs of a given area taken over a period of years. Photographs
should be about 1:5,000 or larger scale. Preferably all photographs in the
series should be taken or printed at the same scale, and taken at the same
time of year.
A photo point is a location from which a specific field of view
can be relocated and rephotographed repeatedly. Changes in the tree population
at a given site are easily seen by examining a series of photographs taken
from a photo point over a period of years. If images are digitized, graphics
software can be used to scale photos to match and even produce animated
"time lapse" presentations.
Ground level photo point
There are two major considerations in establishing an effective photo point.
First, trees and other features which are to be documented should be clearly
visible at the time the original photo is taken as well as in future photographs.
Try to situate the camera well away from vegetation that might subsequently
block the vie