The portions of the Atlantic forest region, adjoining the extensive western woodless tracts, give Mayr an opportunity of considering the origin of these areas, poor in wood, but for the most part stocked with tall grasses. It may be laid down as a general statement that they are caused by the dry climate of the prairies. The author, however, rightly observes, that a great portion of the prairies of North America possesses a climate moist enough to render the existence of forest possible, and that other non-climatic causes must be considered to account for the absence of trees. This question is also discussed by Sergent in the introduction to his book which has been already referred to. The annual forest fires have destroyed the primeval forest in this region, and prevent its restoration. A zone, poor in wood, bordering along the west side of the Atlantic forest tract and separating it from the true prairie land, is described by Sergent as prairie with less than 20 per cent of forest. This zone, which to the east has a remarkable bending towards Lake Michigan, was, before the introduction of woods, limited to the damp low land protected against fire, which extended along the sides of the water-courses.

When the land was brought under cultivation, and fields took the place of grassy plains and checked the fires, the forest spread and it has therefore happened in Wisconsin, Illinois, Iowa and other States, that the forest is naturally regenerating itself in many places by seed or coppice shoots, and continually increasing in area. In Western Texas, latitude 30 degrees, extensive areas of woods of Mesquit bean Prosopis juliflora, had altogether disappeared owing to the annual forest fires.

Irregular underground stocks sent out shoots which were destroyed annually by the fires, and, so to speak, coppiced. Now, however, that the fires have become less frequent and severe, large areas have become re-stocked with this species, partly by seedlings and partly by coppice shoots. In a similar way in all provinces of British India on both sides of the Ganges, the forest is extending at the cost of the Savannah wherever the annual forest fires have been checked and other causes do not hinder its re-growth. Much

has also been done in several of the States by plantations, which flourish in this badly wooded country wherever the climate is sufficiently moist. What Sergent states of Kansas will illustrate the above remarks. In the eastern Counties of this State, very extensive plantations have succceeded. In the central and western parts of Kansas, however, where the climate is dry, all attempt to introduce woods have hitherto failed. Even in Missouri, east of Kansas, are a few partly wooded tracts and here the recent spread of woodland is ascribed to the law against forest grazing. (Sergent, p. 560.)

In the Northern Pine zone of the great Atlantic forest region, Pinus Strobus, the white pine, as it is called in America, (in Europe known as the Weymouth Pine,) is the most important species for the Forester. Formerly, chiefly mixed with broadleaved trees, it formed enormous forest tracts from the north coast of the Gulf of St. Lawrence to northern Georgia, and westwards beyond the sources of the Missouri to the river Winnipeg. At present, the only considerable supplies of this valuable timber are to be found in Canada, its principal home, and in the United States in the Lake Districts of the States of Michigan, Wisconsin and Minnesota. These three States at present yield about 80 per cent of the white pine timber used by the United States.

It is long since the Weymouth Pine* was introduced into Europe, and it can well be said that its introduction into Germany was a lucky venture, the importance of which is not, perhaps, as yet, sufficiently recognized.

Even without considering its rapid growth, and its great production of wood, it has two extremely valuable qualities, in its prolonged cover of the soil and dense fall of needles. In the State forest of Nürnberg, every year a vast amount of forest litter must be obtained; and the Weymouth Pine would have been planted upon a large scale were not the seed so dear. Both Fernow and Mayr confirm the statement that most of the Weymouth Pine seed purchased in the United States is imported there from Europe. The exploitation of the Forests of Weymouth Pine in the lake districts is carried out on a vast scale. It is a system of pillaging the forests (Raubwirthschaft) on the greatest scale. These operations have only one object, to bring as much timber as possible out of the forest in the shortest possible time and to make money. Only the best trees are felled and the rest are destroyed by ǹre.

The remains of such a forest after the first forest fire has destroyed the twigs and leading and side shoots of the trees, present a remarkable appearance. Between the standing blackened and partly carbonised stems of the broad leaved and other trees which have not been felled, are the stumps of the felled pines, and

* Pinus Strobus was introduced into England in 1705 and Lord Weymouth was the first to plant it out on a large scale. It may, however, have been cultiva ted in Paris in the 16th century. Taxodium distichum and Juniperus virginiana were introduced into Europe in the first half of the 17th century.

the ground covered with wood which would not have paid for its removal. Whatever portions of this wood do not rot, are burned by the annual fires. However, such wasted forests are not altogether without hope of recovery. In the hand of a skilful forester they could soon become productive again. We are not far off the time when, in the Lake districts, capital will be applied on a large scale for productive Forestry. At present, such devastated forests are to be had for a trifling sum, and splendid results would follow from good management. In 1880, in three Lake districts of Michigan, Wisconsin, and Minnesota there were estimated to be 7,000 million cubic feet of standing timber of Weymouth Pine, whilst in the last ten years 6,205 millions cubic feet have been felled and exported, in 1889 alone 750 millions cubic feet. There is therefore little more left than can be exported in a single year.

Many of the large saw-mills have supplies of logs for several years, but others of them have already been obliged to stop work or to get timber from Canada.

Chicago alone, the great port to the south of Lake Michigan, which in part owes its rapid rise to the timber trade, imports yearly 161,210,000 c. ft. of wood, all of Weymouth Pine. These forests also yield other coniferous wood and quantities of broad leaved wood. As a comparison, it may here be noted that the annual yield of the Prussian State Forests is 205,800,000 cubic feet which is the annual yield of 6,750,000 acres. The forest timber f yard was established in Chicago in 1834, but only by 1843 had the timber attained large proportions. Broad leaved timber was imported at an early date, but at first only in small quantities. Professor Beal (in Garden and Forest, 1890, p. 559) relates that he brought out from the forest logs of Liriodendron tulipiferum in 1880 to a country store where they were exchanged for various wares. As soon as the supplies of Weymouth Pine in North America and in Canada have been exhausted, the trade will only have the Southern Pine Forests and those of Californian redwood and of Douglas fir in the west to look to.

In the Forests of Weymouth Pine, besides broad leaved trees, there are two other pines, which are chiefly restricted to special kinds of soil :—the gray pine, Pinus Banksiana, preferring the poorest sandy soils, a tree of little value but widely spread, from New Brunswick and the Southern coast of Hudson's Bay to the Mackenzie River and the eastern slopes of the Rocky Mountains and southwards to lat. 65 degrees; and the red pine, Pinus resinosa, a valuable similar tree formerly exported under the name of Strobus. Mayr says "the soil of the Weymouth Pine gives the best meadows; that of the Red Pine, inferior 'wheat soil, whilst that of Banks' Pine does not repay the cost ' of clearing for cultivation." We have now to describe the northern coniferous forest, which Mayr terms the coniferous forest of the sub-arctic region, Sergent, the northern forest tract (extending in both the Atlantic and Pacific regions) and

Drude, in the work mentioned below* includes in the glacier forest tract of Alaska and British North America. This region is confined to forest bordering on the Arctic Circle in Alaska and British North America. At the summits of the Alleghanies, however, Picea nigra and Abies Fraseri are found, which belong to it. In Labrador, the forest limits do not extend beyond Lat. 60 degrees, but at the mouth of the Mackenzie river and in Alaska it extends beyond the Arctic circle, as far as Lat. 70 degrees. In the northern part of this region, the forest is thin and scattered. The white and black spruce (Picea alba and nigra) are characteristic trees, whilst the valleys and lower plains are stocked with poplars, birches, and willows. In the Pacific region, Picea sitchensis is found from near the coast to a distance of 50 miles from the sea. In the Atlantic region, the above-mentioned grey pine (P. Banksiana) extends from the eastern slopes of the Rocky Mountains to Lat. 65 degrees. This immense forest tract is poor in species; and, as already mentioned, four trees are found throughout the whole breadth of the continent. These are:-) -1, Betula papyrifera, Marshall (Canoe or paper birch) from Labrador to Alaska and from Scandinavia and Washington to British Columbia; 2, Populus tremuloides (Aspen) Labrador to Alaska, Pennsylvania and Kentucky to California, and in the highest parts of the Rocky Mountains to New Mexico and Arizona; 3, Populus balsamifera (the balsam poplar or Tacamahac) from Hudson's Bay to Alaska, New England to Washington and British Columbia; 4, Picea alba (white spruce) from Labrador to Alaska and from Vermont to Sitka and British Columbia,

The second principal snb-division, according to Mayr, "the Prairie" includes the eastern part of Sergent's Pacific tract and the western part of his Atlantic tract, and indeed the greatest part of the great central scantily covered plateaux and of the true Prairies. Sergent terms Prairie, the scantily wooded zone to the west of the Atlantic forest region, and the intermediate gradations between this and the central treeless plateau. In this zone, the forest covers less than 20 per cent of the area, and is chiefly found along the banks of the streams. In this scantily wooded region the climate is moist enough for the exist ence of forests, and the grass has only got the upper hand owing to annual forest fires. Dr. Mayr divides the tract he terms Prairie into three longitudinal zones. The first, the high land to the east of the Rocky Mountains, sloping down towards the east. He attributes the absence of forest here, to the low relative humidity of the air, although the annual rainfall is sufficient for tree growth. Towards the east, the prairie is greatly extended by fire. As already observed, this zone includes a large portion of the scantily wooded tract termed Prairie by Sergent, who places

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* Florenkarte von Nord America-Berghaus, Physicalischer Atlas, 1887, No. 50. Handbuch der Pflanzengeographie, Stuttgart, 1890, p. 435.