. A primer of forestry : part I, the forest. Forests and forestry. 20 THE FOEEST. slopes of a high mountain .are commonly starved and stunted in com- parison with the vigorous forest lower down. The Western Chinqua- pin, which reaches a height of 150 feet in the coast valleys of northern California, is a mere shrub at high elevations in the Sierra Nevada. The same thing is often observed in passing from the more temperate reoions to the far north. Thus the Canoe Birch, at its northern limit, rises only a few inches above the ground, while farther south it becomes a tree sometimes 120 feet in h
. A primer of forestry : part I, the forest. Forests and forestry. 20 THE FOEEST. slopes of a high mountain .are commonly starved and stunted in com- parison with the vigorous forest lower down. The Western Chinqua- pin, which reaches a height of 150 feet in the coast valleys of northern California, is a mere shrub at high elevations in the Sierra Nevada. The same thing is often observed in passing from the more temperate reoions to the far north. Thus the Canoe Birch, at its northern limit, rises only a few inches above the ground, while farther south it becomes a tree sometimes 120 feet in height. THE REPRODUCTIVE POWER OF TREES. Another matter which is of the deepest interest to the forester is the reproductive power of his trees. Except in the case of sprouts and other growth fed old roots, this depends first of all on the quantity of the seed which each tree bears; but so many other considerations affect the result that a tree which bears seed abundantly may not re- produce itself very well. A part of the seed is always unsound, and sometimes much the larger part, as in the case of the Tulip Tree. But even a great abun- danceof sound seed does not always insure good Fig. 10.—Wmged seeds: 1, Basswood; 2, Boxelder; 3, Elm, 4, Pir; reproduction. Thcsccds o to 8, Pine. ^^^^ ^^^^ right surroundings for successful germination, or the infant trees ma}' perish for want of water, light, or suitable soil. Where there is a thick la3'er of dry leaves or needles on the ground, seedlings often perish in great numbers because their delicate rootlets can not reach the fertile soil beneath. The same thing happens when there is no humus at all and the surface is hard and dry. The weight of the seed also has a power- ful influence on the character of reproduction. Trees with heavy seeds, like oaks, hickories, and chestnuts, can sow them only in their own neighborhood, except when they stand on steep hillsides or on the banks of streams, or when birds and squirrels carry the nut
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