(3) Between these north and south coniferous belts, lay the great broad-leaf or hardwood forest, Fig. 48, which constituted the greater part of the Eastern Forest and characterized it. It was divided into two parts by an irregular northeast and southwest line, running from southern New England to Missouri. The southeast portion consisted of hardwoods intermixed with conifers. The higher ridges of the Appalachian Range, really a leg of the northern forest, were occupied by conifers, mainly spruce, white pine, and hemlock. The northwest portion of the region, particularly Ohio, Indiana, and Illinois, was without the conifers. It was essentially a mixed forest, largely oak, with a variable mixture of maples, beech, chestnut, yellow poplar, hickory, sycamore, elm, and ash, with birch appearing toward the north and pine toward the south.
Taking the Eastern Forest as a whole, its most distinguishing feature was the prevalence of broad-leaved trees, so that it might properly be called a deciduous forest. The greatest diversity of trees was to be found in Kentucky, Tennessee and North Carolina, and this region is still the source of the best hardwood lumber.
This great eastern forest, which once extended uninterruptedly from the Atlantic to the Mississippi and beyond, has now been largely lumbered off, particularly thru the middle or hardwood portion, making way for farms and towns. The north and south coniferous belts are still mainly unbroken, and are sparsely settled, but the big timber is cut out, giving place to poorer trees. This is particularly true of the white pine, "the king of American trees," only a little of which, in valuable sizes, is left in Michigan, Wisconsin and Minnesota. In the same way in the south, the long-leaf pine, once the characteristic tree, is fast being lumbered out.
The Western or Pacific forest extends two great legs, one down the Rocky Mountain Range, and the other along the Pacific coast. Between them lies the great treeless alkali plain centering around Nevada, Fig. 49. In these two regions coniferous trees have almost a monopoly. Broad-leaved trees are to be found there, along the river beds and in ravines, but they are of comparatively little importance. The forest is essentially an evergreen forest. Another marked feature of this western forest, except in the Puget Sound region, is that the trees, in many cases, stand far apart, their crowns not even touching, so that the sun beats down and dries up the forest floor, Fig. 50. There is no dense "forest cover" or canopy as in the Eastern Forest. Moreover these western forests are largely broken up, covering but a part of the mountains, many of which are snow-clad, and interrupted by bare plains. Along the creeks there grow a variety of hardwoods. It was never a continuous forest as was the Eastern Forest. The openness of this forest on the Rockies and on the eastern slopes of the Sierra Nevadas is in marked contrast to the western slopes of the Sierras, where there are to be seen the densest and most remarkable woods of the world, Fig. 51. This is due to the peculiar distribution of the rainfall of the region. The precipitation of the moisture upon the northwest coast where the trees are dripping with fog a large part of the time, is unequaled by that of any other locality on the continent. But the interior of this region, which is shut off by the high Sierra Nevadas from the western winds, has a very light and irregular rainfall. Where the rainfall is heavy, the forests are dense; and where the rainfall is light, the trees are sparse.
Fig. 50. Open Western Forest, Bull Pine. Flagstaff, Arizona. U. S. Forest Service.
Along the Rockies the characteristic trees are Engelmann's spruce, bull pine, Douglas fir, and lodgepole pine. As one goes west, the variety of trees increases and becomes, so far as conifers are concerned, far greater than in the east. Of 109 conifers in the United States, 80 belong to the western forests and 28 to the eastern. The Pacific forest is rich in the possession of half a dozen leading species—Douglas fir, western hemlock, sugar pine, bull pine, cedar and redwood.
Fig. 51. Dense Forest of Puget Sound Region, Red Fir and Red Cedar. Pierce Co., Washington. U. S. Forest Service.
But the far western conifers are remarkable, not only for their variety, but still more for the density of their growth, already mentioned, and for their great size, Fig. 52. The pines, spruces and hemlocks of the Puget Sound region make eastern trees look small, and both the red fir and the redwood often grow to be over 250 feet high, and yield 100,000 feet, B.M., to the acre as against 10,000 feet, B.M., of good spruce in Maine. The redwood, Fig. 53, occupies a belt some twenty miles wide along the coast from southern Oregon to a point not far north of San Francisco and grows even taller than the famous big trees. The big trees are the largest known trees in diameter, occasionally reaching in that measurement 35 feet.