INTERPRETATION OF PHOTOS 



The quality of young hardwood trees is 

 determined by the condition, size, and ex- 

 tent of naturally occurring external charac- 

 teristics. The stand density, aspect, and 

 moisture all have a direct relationship to total 

 height, dbh, crown class, crown ratio, size 

 and number of live and dead limbs, stem 

 curvature, epicormic branch development, 

 forking, and external defects. 



A detailed record of specific defect change 

 and development can be made by analyzing 

 stereo pairs at different photo intervals. 

 Limb size, epicormic branching, and over- 

 growths can be recorded from one photo- 

 measurement period to the next. Figures 2 

 through 5 show a progression of three in- 

 dividual quality changes. The inset photos 

 indicate the detail that can be seen by ex- 

 amining stereo pairs. For example, the 1-inch 

 live limb shown in Figure 2A in 1960 was 

 dead by 1965 (Fig. 3A), but still remained 

 on the tree in 1972 (Fig. 4A). However, by 

 1978 (Fig. 5A) the limb had fallen off and 

 an overgrowth had formed. The natural 

 pruning of this limb is possibly a result of 

 live-limb behavior when a tree remains in a 

 densely stocked stand. If the stand had been 

 released to 30 square feet of basal area, the 

 results might have been much different. 



Figure 2A also shows a small 1/8-inch 

 epicormic branch formed at the base of the 

 above mentioned 1-inch branch. In 1965 

 (Fig. 3 A) and 1972 (Fig. 4A) the epicormic 

 branch was still alive and had grown to 

 1/4 inch and 1/3 inch, respectively. The 

 epicormic branch was almost 1/2 inch by 

 1978 (Fig. 5A). 



Figure 2B shows a 3/4-inch live limb in 

 1960. Between 1960 and 1965 this limb 

 grew to 1 inch, but by the time the 1965 

 photo (Fig. 3B) was taken the limb had died. 

 This dead limb remained on the tree another 

 7 years (Fig. 4B), and by 1978 (Fig. 5B) 

 the limb had fallen off and an overgrowth 

 remained as a past-limb indicator. 



Figure 2C shows the start of a butt swell. 

 The size and form of the butt swell appears 

 to be diminishing (Fig. 3C and 4C), but this 



is an illusion because the swell remained 

 and the tree increased in diameter (Fig. 5C). 

 The progression shows that the absolute butt 

 swell has stayed about the same and the 

 relative butt swell is diminished because of 

 tree growth. 



Other tree quality characteristics that can 

 be measured and interpreted from stereo pairs 

 are stem curvature and forks. Stem curva- 

 ture can be measured on the photograph by 

 applying a straight edge directly along each 

 tree bole, and then estimating the inches 

 of departure for a given set of tree photos. 



COMPARISON 



For comparison, 30 white oak trees were 

 evaluated by the quality classification system 

 using the relative quality index (Sonderman 

 and Brisbin 1978). The trees were evaluated 

 in the field, and also by stereo -photo analysis 

 in the laboratory. The results of the com- 

 parison showed that 83 percent of the trees 

 had no change in relative quality class, and 

 the remaining 17 percent were misclassified 

 by only one quality class. Misclassification 

 occurred only in the "good" and "medium" 

 relative quality classes. 



APPLICATION 



The technique of interpreting stereo- 

 pair photography provides an insight into how 

 and why quality -related defects in trees 

 develop and change under different cultural 

 treatments. Interpretation of stereo photos 

 aids in developing procedures for stratifying 

 quality in cultural treatment studies, and pro- 

 vides previously unavailable information on 

 the quality development of certain tree 

 species. Actual results will be published in a 

 future publication that describes the effects 

 of thinning treatments on tree quality charac- 

 teristics and growth for 18 years. The forth- 

 coming publication will feature white oak 

 quality development under different stocking 

 levels and will link quality development, as 

 recorded by this system, to silvicultural 

 parameters. 



3 



