116 TREE PLANTER'S MANUAL. 



BATTLING FOR MASTERY. 



The differentiation into dominant growth and laggards takes place in gen- 

 eral earlier and more decidedly on strong soils, also in light-needing sooner 

 than in shade-enduring species, which last keep up an even struggle much 

 longer than the former, so that it is difficult to say which will finally, win, 



ASSISTING NATURE. 



It is to give direction and assist in this struggle, to hasten its results, 

 to obviate, if possible, useless expenditure of energy by timely interference 

 that the forester steps in with the ax. For the natural thinning, as a rule, 

 does not progress satisfactorily for the best quantitative and qualitative 

 development, and hence it is assisted by the forester, it being well under- 

 stood that there is a larger total and more valuable product to be had with 

 a smaller number of individuals through better development of the latter. 



NUMERICAL SCALE. 



It is the number of trees that yield the best result, not the greatest 

 number that we try to keep growing. What this best number is, depends 

 naturally on the kind of tree; it changes also with age, as the trees need 

 more room, and with soil and situation. In the average we would not bo 

 far out of the way to require per tree in the twentieth year 10 square feet, 

 in the fortieth year, 40; in the sixtieth year, 100; in the eightieth year, 125; 

 and in the one hundreth year, 160 square feet growing space, or 4,300, 

 1,100, 435, 350, and 270 trees per acre, respectively, at the ages noted, 

 would represent about the proper average condition of growth. There are 

 from 50 to 75 per cent more shade-enduring trees possible on an acre than 

 light-needing; more trees on poorer soils, sometimes two to four times as 

 many, than on good soils, and more in the valley, sometimes double that 

 of the higher elevations; so that while a pine growth of, say, 60 years may 

 show 500 trees to the acre, a beech growth may contain 750 trees under the 

 same conditions. Prof. B. E. Fernow. 



EFFECTS OF LIGHT COLORS. 



Experimentation has demonstrated that plants of varied species differ 

 in respect to the rays of light which they absorb or reject. About twenty- 

 five years ago, M. Bert reported to the French Academy of Sciences the re- 

 sults of his experiments under the influence of colored lights on twenty-five 

 species of growing plants, belonging to as many families, and exposed to 

 the same conditions. He found 



First That green is almost as obstructive as total darkness. 



Second That red is very injurious, but not so much sp as green, and 

 that it causes plants to elongate in a singular manner. 



Third That yellow is less injurious than the above, but more so than 

 blue. 



Fourth That any one of the colors has a bad effect on plants, and that 

 their union in the proportion that forms white light is necessary to vege- 

 table health. 



