Figure 2. Stereograms of Douglas-fir beetle damage. Scale 1:7,920. A. Panchromatic film (red filter); B. Color film; C. Ektachrome Infrared film.
Photo by: John F. Wear; Robert B. Pope; Peter W. Orr Date: 1966
"Introduction A manager responsible for administering forest lands needs to keep a constant check on the status of the forest resource and the changes that have taken place, or are likely to take place. among the many kinds of information he needs is that on the damage caused by forest insects. Such knowledge may affect his decisions on the amount of allowable cut, his plans for the orderly harvest of timber, the salvage of dead or damaged material, and the control of insect outbreaks.
Keeping track of this damage is usually a difficult and expensive task because the mortality is typically scattered in erratic fashion over vast and often inaccessible areas. Often, excessively high costs can be avoided by using aerial photography, which covers ground more quickly and cheaply than fieldwork, yet provides a permanent in-place record of certain kinds of damage. This manual summarizes the present state of knowledge in this field and presents step-by-step procedures for the best known applications of aerial photography to forest insect surveys in the West.
The literature describes a wide variety of forest insect surveys, some of which can benefit from the use of aerial photos. From the standpoint of aerial photography, it is convenient to group these surveys into four classes, based on the type of information collected: (1) detecting the presence of damage, (2) determining the exact location of the damage, (3) estimating the amount of damage, and (4) estimating the relative size of the insect population and its capacity for future damage."
Photo and excerpt are from: John F. Wear, Robert B. Pope, Peter W. Orr. 1966. Aerial Photographic Techniques For Estimating Damage by Insects in Western Forests. Pacific Northwest Forest and Range Experiment Station (Portland, Or.). U.S. Dept. of Agriculture, Forest Service. 79 p.
Credit: USDA Forest Service, Region 6, State and Private Forestry, Forest Health Protection. Source: Aerial Survey Program digital collection.