228 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
ÜJ 
о 
Z 
< 
ш 
er 
WAVE LENGTH (MILLIMICRONS) 
Fig. 1. Selected curves of light reflectance from tree foliage at Urbana, Illinois, U.S.A., for 
four dates during the 1961 growing season. 
Fig. 2. Cumulative radial growth during 
the 1961 growing season for plantations 
of four species at Urbana, Illinois, U.S.A.