20 
formed of a single species. In the management of both there is, as we 
have seen, one condition which requires the most careful study and 
consideration, namely, the dependence of tree growth on light, by 
which in the forest the ultimate domination of this or the other tree or 
species is determined, 
Especially the varying amounts of light which the different species 
.either need or cau be satisfied with,* and also the rapidity with which 
they grow in height and which gives them a chance of escaping the 
shading exerted by their neighbors, are of interest to the forest 
manager. ' 
Go into the dense forest and see what kinds of trees are vegetating 
in the dense shade of the older trees, and then go into an opening re- 
cently made, an abandoned field or other place, where the full benefit 
of light is to be had by all alike, and you will find a different set alto- 
gether occupying the ground and dominating. In the first case you 
will find, perhaps, beech and sugar maple or fir, and spruce; in the see- 
ond case you may find aspen, poplars, willows, soft maple, oaks, or 
pines, tamarack, ete. 
All trees thrive ultimately best in full enjoyment of light; the leaves 
exercise their functions under its inflaence and feed the tree by assimi- 
lating the carbon of the air and transpirin g the water of the soil, bat 
some, like those first mentioned, can at ieast subsist and their foliage 
functionate with a small amount—they are shade-enduring kinds, they 
usually have a dense foliage, many leaves, and each one needs to dv but 
little work—and exert considerable shade when fully developed, while 
those last named can not exist long without a considerable amount of 
light, having less foliage—they are light-needing kinds. 
To offset this drawback in the constitution of these latter nature has 
endowed them as a rule with the capacity of rapid height growth, to es- 
cape their would-be suppressors, but again. what they have gained in 
the rapidity of development they lose in the length of life; they are 
mostly short-lived species, while the shade-enduring are generally slower 
growers, but persistent and long-lived. Some kinds, like most of the 
oaks, stand between the two; while exhibiting a remarkable capacity 
of vegetating in the shade,they are really li ght-needing species but com- 
paratively slow growers and long-lived. One and the same species be- 
haves also somewhat differently under different soil and climatic condi- 
tions; for instance, as a rule, the light-needing species can endure more 
shade on moist soils and the shade-enduring require more light on drier 
soils. 
In the earliest stages of life the little seedlings of most trees require 
partial shade and are quite sensitive in regard to light conditions, 
Some have such a small range of light and shade endurance that, 
while there may be millions of little seedlings sprouted, they will all 
perish if some of the mother trees are not removed and more light 
eee a 
* See also p. 36 of this balletin, 
