However, with good exposure and development control, photography 
on days of similar atmospheric conditions should yield comparable 
results on an altitude for altitude basis. This implies that the 
photographically recorded seasonal color changes of vegetation 
can be mostly an expression of real vegetational reflectance 
changes. Therefore, with proper control, visual or optical- 
electronic color comparisons of repeated aerial photography of an 
area over time can be used to assess changing physiological- 
morphological vegetational conditions. 
ACKNOWLEDGEMENTS 
The author wishes to acknowledge the financial support and equip 
ment use furnished by the School of Forestry, Fisheries and Wild 
life, University of Missouri and the aerial photography by Surdex 
Corporation of Chesterfield, Missouri. 
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