274 



FORESTRY INVESTIGATIONS U. s. DEPARTMENT OF AGRICULTURE. 



It follows that the forest planter, who desires to produce long and clean shafts and best working 

 qualify of timber, must secure and maintain side shade by a close stand, while the landscape 

 '•arriener, who desires characteristic form, must maintain an open stand and full enjoyment of 

 1 i»bt for his trees. 



Now, as we have seen, different species afford different amounts of shade, and in proportion 



to the shade which they afford can they endure shade. 

 Tbe beech or sugar maple or spruce, which maintain 

 a large amount of foliage under the dense shade of 

 their own crown, show that their leaves can live and 

 functionate with a small amount of light. They are 

 shade-enduring trees. On the other hand, the black 

 walnut, the locust, the 

 catalpa, the poplars, 

 and the larch show by 

 the manner in which 

 their crowns thin out, 

 the foliage being con- 

 fined to the ends of the 

 branches, that their 

 leaves require more 

 light — they are light- 

 needing trees; so that 

 the scale which ar- 

 ranges the trees ac- 

 cording to the amount 

 of shade they exert 

 serves also to measare 

 their shade endurance. 

 In making, there- 

 fore, mixed planta- 

 tions the different 

 kinds must be so 

 grouped and managed 

 that the shady trees 

 will not outgrow and 

 overtop the light need- 

 The latter must either have the start of the former or must be 

 quicker growers. 



RATE OF GROWTH. 



Not only do different species grow more or less rapidly in height 

 and girth, but there is in each species a difference in the rate of 

 growth during different periods of life and a difference in the per- 

 sistence of growth. 



It stands to reason that trees grow differently in different soils 

 and situations, and hence we can not compare different species with 

 lespect to their rate of growth except as they grow under the same 

 conditions. 



Thus the black walnut may grow as fast as or faster than the ash 

 on a rich, deep, moist, warm soil, but will soon fall to the rear in a 

 wetter, colder, and shallower soil. 



Given the same conditions, some species will start on a rapid upward growth at once, like the 

 poplars, aspen, locust, and silver maple, making rapid progress (the most rapid from their tenth 

 to their fifteenth year), but decreasing soon in rate and reaching their maximum height early. 

 Others, like the spruce, beech, and sugar maple,, will begin slowly, often occupying several, 



JS JE7' 



Fig 35 —Sections oi logs showing the relative de\ elopmeut ot 

 knots U horn tue *>rcn\n m the open E> irom tree giown 

 in a dense foie&t a and c vt boils oi knots b dead limb 

 si ' sound knot dk ' dead knot ' 



mg. 



Fig 36.— Scheme to illustrate the ar- 

 rangement of annual growth 1, 2, 3, 

 etc , lepiesent the parts oi the stem 

 grown dunng the first, second thud, 

 etc , t\\ enty -\ ears of the hie ot the 

 tree, k, knots, the shaded part of each 

 is the "dead knot oi lutnbei 



