Report on the lands of the arid region of the United States, with a more detailed account of the lands of Utah

by John Wesley Powell; Willis Drummond; Clarence E. Dutton; Grove Karl Gilbert; A. H. Thompson

TIMBER LANDS.

Throughout the Arid Region timber of value is found growing spontaneously on the higher plateaus and mountains. These timber regions are bounded above and below by lines which are very irregular, due to local conditions. Above the upper line no timber grows because of the rigor of the climate, and below no timber grows because of aridity. Both the upper and lower lines descend in passing from south to north; that is, the timber districts are found at a lower altitude in the northern portion of the Arid Region than in the southern. The forests are chiefly of pine, spruce, and fir, but the pines are of principal value. Below these timber regions, on the lower slopes of mountains, on the mesas and hills, low, scattered forests are often found, composed mainly of dwarfed piñon pines and cedars. These stunted forests have some slight value for fuel, and even for fencing, but the forests of principal value are found in the Timber Region as above described.

Primarily the growth of timber depends on climatic conditions—humidity and temperature. Where the temperature is higher, humidity must be greater, and where the temperature is lower, humidity may be less. These two conditions restrict the forests to the highlands, as above stated. Of the two factors involved in the growth of timber, that of the degree of humidity is of the first importance; the degree of temperature affects the problem comparatively little, and for most of the purposes of this discussion may be neglected. For convenience, all these upper regions where conditions of temperature and humidity are favorable to the growth of timber may be called the timber regions.

Not all these highlands are alike covered with forests. The timber regions are only in part areas of standing timber. This limitation is caused by fire. Throughout the timber regions of all the arid land fires annually destroy larger or smaller districts of timber, now here, now there, and this destruction is on a scale so vast that the amount taken from the lands for industrial purposes sinks by comparison into insignificance. The cause of this great destruction is worthy of careful attention. The conditions under which these fires rage are climatic. Where the rainfall is great and extreme droughts are infrequent, forests grow without much interruption from fires; but between that degree of humidity necessary for their protection, and that smaller degree necessary to growth, all lands are swept bare by fire to an extent which steadily increases from the more humid to the more arid districts, until at last all forests are destroyed, though the humidity is still sufficient for their growth if immunity from fire were secured. The amount of mean annual rainfall necessary to the growth of forests if protected from fire is probably about the same as the amount necessary for agriculture without irrigation; at any rate, it is somewhere from 20 to 24 inches. All timber growth below that amount is of a character so stunted as to be of little value, and the growth is so slow that, when once the timber has been taken from the country, the time necessary for a new forest growth is so great that no practical purpose is subserved.

The evidence that the growth of timber, if protected from fires, might be extended to the limits here given is abundant. It is a matter of experience that planted forests thus protected will thrive throughout the prairie region and far westward on the Great Plains. In the mountain region it may be frequently observed that forest trees grow low down on the mountain slopes and in the higher valleys wherever local circumstances protect them from fires, as in the case of rocky lands that give insufficient footing to the grass and shrubs in which fires generally spread. These cases must not be confounded with those patches of forest that grow on alluvial cones where rivers leave mountain cañons and enter valleys or plains. Here the streams, clogged by the material washed from the adjacent mountains by storms, are frequently turned from their courses and divided into many channels running near the surface. Thus a subterranean watering is effected favorable to the growth of trees, as their roots penetrate to sufficient depth. Usually this watering is too deep for agriculture, so that forests grow on lands that cannot be cultivated without irrigation.

Fire is the immediate cause of the lack of timber on the prairies, the eastern portion of the Great Plains, and on some portions of the highlands of the Arid Region; but fires obtain their destructive force through climatic conditions, so that directly and remotely climate determines the growth of all forests. Within the region where prairies, groves, and forests appear, the local distribution of timber growth is chiefly dependent upon drainage and soil, a subject which needs not be here discussed. Only a small portion of the Rocky Mountain Region is protected by climatic conditions from the invasion of fires, and a sufficiency of forests for the country depends upon the control which can be obtained over that destructive agent. A glance at the map of Utah will exhibit the extent and distribution of the forest region throughout that territory, and also show what portions of it are in fact occupied by standing timber. The area of standing timber, as exhibited on the map, is but a part of the Timber Region as there shown, and includes all of the timber, whether dense or scattered.

Necessarily the area of standing timber has been generalized. It was not found practicable to indicate the growth of timber in any refined way by grading it, and by rejecting from the general area the innumerable small open spaces. If the area of standing timber were considered by acres, and all acres not having timber valuable for milling purposes rejected, the extent would be reduced at least to one-fourth of that colored. Within the territory represented on the map the Timber Region has an extent of 18,500 square miles; that is, 23 per cent. belongs to the Timber Region. The general area of standing timber is about 10,000 square miles, or 12.5 per cent. of the entire area. The area of milling timber, determined in the more refined way indicated above, is about 2,500 square miles, or 3¹⁄₈ per cent. of the area embraced on the map. In many portions of the Arid Region these percentages are much smaller. This is true of southern California, Nevada, southern Arizona, and Idaho. In other regions the percentages are larger. Utah gives about a fair average. In general it may be stated that the timber regions are fully adequate to the growth of all the forests which the industrial interests of the country will require if they can be protected from desolation by fire. No limitation to the use of the forests need be made. The amount which the citizens of the country will require will bear but a small proportion to the amount which the fires will destroy; and if the fires are prevented, the renewal by annual growth will more than replace that taken by man. The protection of the forests of the entire Arid Region of the United States is reduced to one single problem—Can these forests be saved from fire? The writer has witnessed two fires in Colorado, each of which destroyed more timber than all that used by the citizens of that State from its settlement to the present day; and at least three in Utah, each of which has destroyed more timber than that taken by the people of the territory since its occupation. Similar fires have been witnessed by other members of the surveying corps. Everywhere throughout the Rocky Mountain Region the explorer away from the beaten paths of civilization meets with great areas of dead forests; pines with naked arms and charred trunks attesting to the former presence of this great destroyer. The younger forests are everywhere beset with fallen timber, attesting to the rigor of the flames, and in seasons of great drought the mountaineer sees the heavens filled with clouds of smoke.

In the main these fires are set by Indians. Driven from the lowlands by advancing civilization, they resort to the higher regions until they are forced back by the deep snows of winter. Want, caused by the restricted area to which they resort for food; the desire for luxuries to which they were strangers in their primitive condition, and especially the desire for personal adornment, together with a supply of more effective instruments for hunting and trapping, have in late years, during the rapid settlement of the country since the discovery of gold and the building of railroads, greatly stimulated the pursuit of animals for their furs—the wealth and currency of the savage. On their hunting excursions they systematically set fire to forests for the purpose of driving the game. This is a fact well known to all mountaineers. Only the white hunters of the region properly understand why these fires are set, it being usually attributed to a wanton desire on the part of the Indians to destroy that which is of value to the white man. The fires can, then, be very greatly curtailed by the removal of the Indians.

These forest regions are made such by inexorable climatic conditions. They are high among the summer frosts. The plateaus are scored by deep cañons, and the mountains are broken with crags and peaks. Perhaps at some distant day a hardy people will occupy little glens and mountain valleys, and wrest from an unwilling soil a scanty subsistence among the rigors of a sub-arctic climate. Herdsmen having homes below may in the summer time drive their flocks to the higher lands to crop the scanty herbage. Where mines are found mills will be erected and little towns spring up, but in general habitations will be remote. The forests will be dense here or scattered there, as the trees may with ease or difficulty gain a foothold, but the forest regions will remain such, to be stripped of timber here and there from time to time to supply the wants of the people who live below; but once protected from fires, the forests will increase in extent and value. The first step to be taken for their protection must be by prohibiting the Indians from resorting thereto for hunting purposes, and then slowly, as the lower country is settled, the grasses and herbage of the highlands, in which fires generally spread, will be kept down by summer pasturage, and the dead and fallen timber will be removed to supply the wants of people below. This protection, though sure to come at last, will be tardy, for it depends upon the gradual settlement of the country; and this again depends upon the development of the agricultural and mineral resources and the establishment of manufactories, and to a very important extent on the building of railroads, for the whole region is so arid that its streams are small, and so elevated above the level of the sea that its few large streams descend too rapidly for navigation.