FORESTRY AND CONSERVATION 343 



shade, the total wood formation is less than in an isolated tree, 

 favorably placed. Just so the dominant trees in a forest i. e., those 

 which have their crowns above all others show, of course, the ad- 

 vantage they have over the inferior trees which are suffering from 

 the shade of their neighbors. 



Finally, if we would take into consideration an entire forest 

 growth, and determine, for instance, how much wood an acre of 

 such forest produces at different periods, we must not overlook the 

 fact that the number of trees per acre changes as the trees grow 

 older. Some of them are overshaded and crowded out by the others, 

 so that a young growth of spruce might start with 100,000 little 

 seedlings to the acre, of which in the twentieth year only 10,000 

 would be alive, while in the fortieth year the number would be re- 

 duced to 1,200, and in the hundredth year to 280. Hence the rate 

 of growth of any single tree gives no idea of what the acre of forest 

 will do. 



Thus, while a single good, white pine might grow the fastest in 

 volume when about one hundred years old, then making wood at the 

 rate of, say, 1.5 cubic feet per year, an acre of pine on good soil, con- 

 taining about 1,600 trees, may make the most wood in the thirtieth 

 year, then growing at the rate of 170 cubic feet per acre, while in the 

 hundredth year the rate would not exceed 70 cubic feet; and an 

 acre of pine in a poorer location, with about 1,400 trees, may make 

 the most wood in the fortieth year, at the rate of 100 cubic feet per 

 acre. From the consideration of the relation of light conditions to 

 soil conditions, to form development, and to rate of growth, we may 

 make the following deductions of interest to the forest planter: 



In order to secure the best results in wood production, in quan- 

 tity and quality, at the same time preserving favorable soil condi- 

 tions, the forest should be composed of various species, a mixture 

 of light-needing and shade-enduring kinds. The light-needing 

 ones should be of quicker growth; the shady ones, in larger num- 

 bers, should be slower growers. For the first fifteen to twenty-five 

 years the plantation should be kept as dense as possible, to secure 

 clear shafts and good growth in height; then it should be thinned, 

 to increase crown development and diameter growth ; the thinning, 

 however, is not to be so severe that the crowns can not close up 

 again in two or three years; the thinning is to be repeated again 

 and again, always favoring the best developed trees. 



Reproduction. All trees reproduce themselves naturally from 

 seed. Man can secure their reproduction also from cuttings or 

 layers ; and some kinds can reproduce themselves by shoots from the 

 stump when the parent tree has been cut. This latter capacity 

 is possessed in a varying degree by different species ; chestnuts, oaks, 

 elms, maples, poplars, and willows are most excellent sprouters; 

 most conifers do not sprout at all, and the shoots of those that do 

 sprout soon die (Sequoia or California redwood seems to be an ex- 

 ception). Sprouts of broad-leafed trees develop differently from 

 seedlings, growing very rapidly at first, but soon lessening in the 

 rate of growth and never attaining the height and perhaps not the 



