332 HORTICULTURE, FORESTRY, FLORICULTURE 



acts favorably upon the soil, while if the litter is exposed to light, an 

 undesirable, partly decomposed "raw" humus is apt to be formed. 



Favorable soil conditions, then, require shade, while wood 

 growth is increased by full enjoyment of light; to satisfy both re- 

 quirements, mixed planting, with proper selection of shade-enduring 

 and light-needing species, is resorted to. 



As the different species afford shade in different degrees, so 

 they require for their development different degrees of light. The 

 dense foliage of the beech, with a large number of leaves in the 

 interior of the crown, proves that the leaves can exist and perform 

 their work with a small amount of light ; the beech is a shade-endur- 

 ing tree. The scanty foliage of the birches, poplars, or pines shows 

 that these are light-needing trees ; hence they are never found under 

 the dense shade of the former, while the shade-enduring can develop 

 satisfactorily under the light shade of the thin-foliaged kinds. 

 Very favorable soil conditions increase the shade endurance of the 

 latter, and climatic conditions also modify their relative position in 

 the scale. 



All trees ultimately thrive best i. e., grow most vigorously - 

 in the full enjoyment of light, but their energy then goes into 

 branching. Crowded together, with the side light cut off, the lower 

 lateral branches soon die and fall, while the main energy of growth 

 is put into the shaft and the height growth is stimulated. The 

 denser shade of the shade-enduring kinds, if placed as neighbors to 

 light-needing ones, is most effective in producing this result, pro- 

 vided that the light is not cut off at the top ; and thus, in practice, 

 advantage is taken of the relative requirements for light of the 

 various species. The forester finds in close planting and in mixed 

 growth a means of securing tall, clear trunks, free from knots, and 

 he is able, moreover, by proper regulation of light conditions, to 

 influence the form of development, and also the quality of his crop, 

 since slow growth and rapid growth produce wood of different 

 character. 



There are some species which, although light foliaged and 

 giving comparatively little shade, are yet shade enduring i. e., can 

 subsist, although not develop favorably, under shade; the oaks are 

 examples of this kind. Others, like the black cherry, bear a dense 

 crown for the first twenty years, perhaps, seemingly indicating 

 great shade endurance; but the fact that the species named soon 

 clears itself of its branches and finally has a thin crown, indicates 

 that it is light needing, though a good shader for the first period of 

 its life. Others, again, like the catalpa, which is shady and shade 

 enduring, as the difficulty with which it clears itself indicates, leaf 

 out so late and lose their foliage so early that their shading value is 

 thereby impaired. Black locust and honey locust, on the other 

 hand, leave no doubt either as to their light-needing or their inferior 

 shading quality. 



That soil conditions and climatic conditions also modify crown 

 development and shade endurance has been well recognized abroad, 

 but in our country this influence is of much more importance on 



