130 



AMERICAN FORESTRY 



(3.) Inte mediate: Healthy trees, 

 but far enough below the normal so as 

 to be shaded from above as well as on 

 the sides. Such trees are still thrifty, 

 and usually capable of making full 

 growth if given enough light. 



(4.) Suppressed: Those so far be- 

 hind and completely shaded that the 

 crown development is not much more 

 than enough to keep the tree alive. 

 Such trees may, or may not, recover 

 full vigor if given enough light, depend- 

 ing mostly on the species and the degree 

 of suppression. As a rule, even if re- 

 covery is possible, it will be years before 

 full vigor is regained. 



A fifth class, of "dead" trees, is 

 sometimes included. 



Again, different kinds of trees differ 

 very much in their demands for light. 

 Spruce can stand a very large amount 

 of shading, and does not do well in the 

 open; while the Scotch pine demands a 

 great amount of light, and can stand 

 very little, if any, shading. Trees 

 which can stand a considerable amount 

 of shade are called tolerant, those that 

 demand much light and cannot endure 

 shade are called intolerant. 



Also, individual t ees differ at differ- 

 ent periods of their life with regard to 

 their light relations. Most trees can 

 stand at least a moderate degree of 

 shade at the start, and generally demand 

 an increasing amount of light as they 

 grow older. 



The demand for Hght also varies with 

 the situation and district in which the 

 tree is growing. 



It is thus important to know the 

 light requirements, not only of the 

 different species, but also at different 

 periods in the life of these species. 



Proper forestry methods aim, as far 

 as practicable, to assure enough light 

 to the best individuals of the best spec- 

 ies, so as to allow them to make their 

 best growth, and at the same to maintain 

 the stand dense enough to produce 

 good, tall, clean trunks. 



There is also an intimate relationship 

 between light and maintenance of the 

 quality of soil, and such features as the 

 seed-bearing qualities of the tree. 



As with moisture, so with light, a 

 study must be made in each locality of 



the tolerance of shade by different 

 species, and the forest management 

 must be very largely based on the 

 needs of the trees favored. 



As with all other plant growth, the 

 kind of soil affects very largely the kind 

 of tree growth foimd on it, and the 

 quality of that growth. Thus, the red 

 pine can grow on the poorest of sands, 

 while the basswood must have a rich 

 soil. 



Any tree will do better on a good 

 soil than on a poor one. But we must 

 not use a tree which requires a good soil 

 on soil of inferior quality. 



Just as in farming, good methods 

 maintain and improve the qualities of a 

 soil, while poor methods — the ordinary 

 kind — impoverish the soil, so it is with 

 forestry. The leaves and other decay- 

 ing vegetable matter add very much to 

 the richness of the soil, forming a good 

 humus and leaf mold. But if exposed 

 to too much light and heat, this humus 

 does not form from the leaves and their 

 nourishment is wasted. So one of the 

 gmdes to proper forest practice is to 

 maintain such a cover as will improve 

 the soil conditions. This is generally 

 accomplished by maintaining, as nearly 

 as possible, a complete shade for the 

 ground. 



At times when reproduction by seed 

 from standing trees is desired, however 

 sufficient light must be given to do away 

 with the litter, and thus provide better 

 seed-bed conditions. 



The requirements of trees with re- 

 gard to soil must also be studied, and 

 only those species used which are 

 adapted to the quality of soil on the 

 site on which grown. 



The Species itself has much to do with 

 the rate of growth. Certain species, as 

 hemlock, or native red spruce, are 

 naturally very slow growers, while 

 others, as Carolina poplar, are naturally 

 very rapid growers. Of course, all 

 species will grow better on good soils 

 than on poor ones; and under proper 

 forestry methods will grow much better 

 than under poor methods. At the same 

 time, it is important, other things being 

 equal, to favor the most rapid growing 

 species. Thus, generally, red oak 

 should be favored over white oak, as it 



