66 Richard H. Boerker 
From these tables it will be seen that Pinus ponderosa increases 
its length of stem with a decrease in light intensity both at the 
age of two and at three months. This is likewise true for Pinus 
strobus. For Robinia pseudacacia, however, both at the age of 
two and three months, there is a striking decrease in stem height 
with a decrease in light intensity. Quercus rubra behaves the 
same way, except that the length of stem is greater in the medium 
shade than in the dense shade. This development is shown very 
well by the accompanying photographs. 
In the case of all species it is strikingly shown that the length 
of the tap root and the total length of the laterals decrease with 
decrease in light intensity. . 
In so far as the stem and its relation to light is concerned it 
is quite evident that hardwoods behave differently from conifers. 
As has been pointed out conifers tend to increase their height ~ 
growth with decrease in light intensity while hardwoods tend to 
decrease this growth with decrease in light intensity. Evidently - 
conifers can adapt themselves to these unfavorable light condi- 
tions better than hardwoods. In-the hardwoods the reciprocal 
relation of roots and stem in their dependence upon light is strik- 
ingly shown. 
Tue Errect oF Soil Depth upon Stem AND Root DEVELOPMENT 
Conifers 
Stem Measurements Root Measurements 
Deerecsisollbenth Pinus pond. P.strobus | P. ponderosa (3 Mos.) 
2 Mos., 3 Mos., 2 Mos., Tap, Laterals, 
Cm. Cm. Cm. Cm. Cm. 
IDES DRe es ata Lanse ae 2.85 2.69 4.35 9.51 | 47 
Mie dimen Sates aoe eae 2.706 2.59 4.31 BO || apie 
Shallow: hae eee 2.60 2.68 4.25 R07 | Ar 
Hardwoods 
Stem Measurements Root Measurements (Tap) 
Desa Soil Osis R. pseudacacia Q. rubra | Rob. pseud.| QO. rubra 
2 Mos., 3 Mos., 5 Mos., 3 Mos., 5 Mos., 
Cm. Cm. m. Cm, Cm. 
Dee psa ee ee ae 6.45 7.20 6.50 TSS 20.4 
IMISChITIING SaGkboddognescbs 6.00 7.02 9.40 9.64 13.8 
Shallowe seekers nee 5.70 6.04 5.90 3.30 6.9 
