So far, however, we have been considering how to make the most of a stand of many ages, due to constant reproduction permitted by the light supply in a fairly open forest. On the other hand, yellow pine sometimes produces a mature stand so heavy that there is little young growth beneath it, or even a thin old stand with either little reproduction or an invasion of lodge-pole pine. Such conditions are usually due to fire at some period. In the first of these cases, usually the dense stand has resulted from a fire which destroyed its predecessor not so completely as to remove the seed supply, but sufficiently to afford light for a more uniformly dense crop of seedlings than would occur in the normal forest.

These have been thinned out as the stand grew old, but never to a degree which allowed much reproduction beneath them. The natural cycle will be begun again in time, for toward the end of the life of this unusually heavy stand, seedlings will begin to appear gradually as individual old trees die and admit more and more light. The other exceptions described are due to more recent ground fires which have destroyed only the less hardy young growth and perhaps also encouraged the lodge pole which, within its range, is always quick to take burned ground.

The same result is almost sure to follow the "Indian" method of forest protection sometimes advocated, which consists of purposely running ground fires frequently in order to prevent acc.u.mulation of sufficient debris to make an accidental fire fatal to timber of commercial size. While such immunity may be secured, and perhaps without sacrifice in stands so heavy as to have no reproduction or when the latter has already been destroyed, it is obviously at the expense of young growth if any exists. The counter argument that a small proportion escaping will be sufficient for the second crop is fallacious, because good timber will not be produced from these scattering seedlings subjected to strong light by later logging.

Other means are necessary if the forest is to be reproduced.

This brings us to the possible management of yellow pine as an even-aged forest. Thoughtful foresters are beginning to suspect that while the "Indian" system of fire protection will usually be fatal if ordinary logging practice is followed, it may serve as an adjunct to a system which, if carefully applied, will be better than selection cutting for some of our pine areas. This plan is suggested where there is little young growth worth protecting and consists of depending upon seed trees almost entirely for reproduction, protecting carefully until the resultant even-aged second growth is large enough to stand Blight fire, and then burning periodically at such a season and with such safeguards as will prevent the fire from being injuriously severe.

Not only are there many existing forests where absence of small trees will permit clean cutting without sacrifice, but the same condition is likely to occur eventually in stands following selective logging if the second cut is long delayed. Although a good representation of all ages under the diameter limit remains, the density of this may become too great to allow further reproduction, and in time the dominant trees will shade out all smaller growth. To allow this purposely, choosing heavy cuts at intervals long enough to mature the crop from seed rather than frequent light cuts of a constantly replenishing stand, thus reducing the necessity of fire prevention, is the aim of those who favor clean cutting as the most practicable system. They a.s.sume that additional investment in seed trees, or planting to insure prompt starting of a new crop after cutting, will be unnecessary or at least offset by the smaller fire charge and greater economy of logging.

Theoretically, such practice with a species adapted to the selective method is uneconomical, for the ground is not fully utilized. Accidental open places in the stand are not occupied by young trees which would otherwise fill them. Time is lost by not starting the second crop until after logging, for were there no fire previously there would be considerable seedling growth which, although perhaps dormant because of shade, would begin to amount to something much quicker than that supplied by seed trees afterward. Nor is the system feasible where there is much fir or other species less fire-resisting than pine. It is dangerous in practice except where there is very little combustible matter on the ground and fire is generally easy of control, and exceedingly dangerous to advocate because serves as a pretext and example for indiscriminate carelessness with fire under all conditions. Finally, the alleged immunity of pine from injury by ground fires is exaggerated. As a matter of fact, while the whole stand is seldom perceptibly hurt, the immediate or gradual death of a good tree here and there thins the stand very considerably in a few years and it is such a thinning process in the past which makes many pine tracts bear but 5,000 feet to the acre where otherwise they would yield two or three times as much. Scorching also r.e.t.a.r.ds the growth of trees not actually injured otherwise.

The technical objections given above may sometimes be offset by practical advantages and the system is likely to receive expert approval for certain conditions provided it is not used as a cloak without taking sincere steps to replace the destroyed second growth by adequate seed trees or artificial seeding. The latter danger may easily warrant public alarm manifested by restrictive laws. Universal ground burning of green timber will distinctly reduce the prospect of una.s.sisted natural reforestation on the great area of potential timber land in which, as a resource, regardless of ownership, the public is vitally interested. Under present conditions at least, a large proportion of this is likely to be logged without any view to a future crop. It is questionable whether any state should, or will, legally approve ground burning except under stipulation of proper management thereafter.

Unfortunately, it is necessary, in concluding this discussion of yellow pine, to admit that while an attempt has been made to outline the methods which will insure a second crop, the promise of satisfactory financial return is more doubtful than that offered by some other species. Compared with the typical coast trees, such as Douglas fir, spruce and hemlock, the growth is slow and the yield small.

The chief circ.u.mstances in its favor are low land values, lesser fire risk, cheapness and certainty of reproduction and excellent market prospects. Less investment compensates somewhat for longer rotation and smaller yield. Low taxation, however, is an absolute essential.

WESTERN WHITE PINE (_P. Monlicola_)

Although as a distinct forest type this valuable tree is limited chiefly to Idaho, it occurs occasionally in mixture or small tracts over a wide range, and no reason appears why its commercial importance should not be extended by planting on cut-over lands. Its high value, rapid growth and heavy yield make it a particularly promising species for growing under forestry principles. Its chief requirements for success are fairly good moist land, access by the seed to mineral soil and ample light for the young seedlings.

Except that it is more fastidious as to soil, white pine usually demands about the same treatment as that prescribed for Douglas fir, including clean cutting, slash burning and establishing a new even-aged stand by seed trees or artificial restocking. Under favorable conditions the stand is nearly even-aged, with little undergrowth except of undesirable species. What small pine may exist is seldom thrifty enough to be worth saving, so the best thing is to clean off the ground for the double purpose of removing weed trees and favoring valuable reproduction. Like that of fir, the natural rotation of white pine forests seems to have been accomplished often by the aid of fire, and where not given this aid it suffers from lack of suitable seed-bed and from the compet.i.tion of other species already established.

Individual seed trees left in logging are not successful because of shallow root system and almost certain windfall. Replacement must be by seeding or planting, or by leaving small tracts of pine surrounded by cleared fire lines to protect them when the slashing is burned. The size and distance apart of these must be determined by their situation and exposure to wind, considering both the danger of windfall and the carrying of seed. Especially in younger growths, the quant.i.ty of merchantable material tied up in this way is not so great as is sometimes necessary in the case of red fir, where single seed trees may contain several thousand board feet. On the other hand, stumpage value may be high. For this reason artificial replacement may often be more profitable, especially where there is reasonable safety against recurring fire.

A thing to be borne in mind is that white pine seems to reach a healthier and better development when mixed with a small proportion of other species, such as cedar, tamarack, spruce, lodgepole pine and Douglas fir, so there is no object in trying to produce an absolutely pure stand. Some authorities think that 60 per cent of pine, with the rest helping to prune it, is an ideal mixture.

LODGEPOLE PINE (_P. Murrayana_)

Present interest in private reproduction of this species hardly warrants treating it at length in this publication, although unquestionably it will eventually occupy a higher place in the market than at present and its readiness to seize burned land in many regions will make it a factor whether desired or not. Where yellow pine will grow, the problem is most likely to be to discourage lodgepole compet.i.tion.

In strictly lodgepole territory, however, it may be the only promise of a new forest. Generally speaking, an even-aged growth should be induced by clean cutting if the entire crop can be utilized.

Slash burning in such cases is desirable. The chief difficulty is in providing seed supply, for either individual seed trees or small groups are almost certain to be blown down. Experiments so far indicate that heavy strips must be spared, chosen to afford the least present loss and safeguarded by fire lines.

In some lodgepole stands, especially where only certain sizes are marketable, the cutting practically amounts to thinning. Here obviously the effort should be to prevent over-thinning and to remove debris with the least damage to the remaining stand. Piling and burning is essential.

SUGAR PINE (_P. Lambertiana_)

This extremely valuable pine, commercially limited to the Oregon and California mountains, is fastidious in its choice of conditions. Not a frequent or prolific seed bearer, it still insists on a moist loose seed-bed and prefers the natural forest floor to burned-over land. It cannot stand drought when young and except on cool northern slopes seedlings may be killed or stunted by exposure to full sunlight. On the contrary it demands more and more light as it grows older and will be suppressed or killed if unable to secure it. Under natural conditions it perpetuates itself best by filling open places in the forest.

For the above reasons, sugar pine is naturally a component of mixed forests and it is doubtful whether it will be successfully grown as a pure stand. Unfortunately, also, logging methods which are both the simplest and most favorable to the reproduction of its a.s.sociates may be discouraging to sugar pine reproduction. Nevertheless, its value warrants strong efforts to favor it and is an argument, where considerable young sugar pine exists, against either clean cutting or the use of fire.

The Forest Service, for which authority much of the above discussion of this species was taken, offers the following general outline for management in California:

"Since the forests in which sugar and yellow pine occur vary greatly in composition, the method of treatment must also vary. For this the forest types already distinguished may form a basis.

"On the lower portion of the sugar pine-yellow pine type, where sugar pine forms but a small proportion of the stand, only the yellow pine should be considered for the future forest. All merchantable sugar pine may therefore be removed. It will be necessary to leave only a few seed trees of yellow pine to restock the ground, although usually it will be a wiser policy to leave a fair stand, since this can be removed as a second cutting when reproduction is established. This procedure would also hold for areas on which yellow pine occurs in nearly pure stands. In these localities dense stands of second-growth yellow pine occur. It will often be profitable, where there is a market at hand, to thin these stands when they are about 30 years old, removing the suppressed trees for mine props. Trees 6, 8 and 10 inches and up are used for this purpose, and sell for from 5 to 6 cents a running foot.

"On the upper portion of the sugar pine-yellow pine type, where both species have about an equal representation in the stand, seed trees of each should be left, wherever practicable, in the proportion of two sugar pines to one yellow pine."

In the fir belt, where sugar pine and fir are the princ.i.p.al species, the fir should be cut clean wherever possible and sugar pine should be relied upon for the future forest.

"On all lands, the Douglas spruce, white fir and incense cedar should be cut whenever possible, and chutes, skidways and bridges should be constructed from the two last named species."

The following specific instructions are issued for marking timber on National Forest sales in the sugar pine-yellow pine type:

"Owing to the large size of the trees, marking in this type of forest should be done with special care, since a slight mistake involves a comparatively large amount of timber.

"On nearly all of the lands included in this type the ground is now but partly and insufficiently stocked with young timber, the areas of forest are constantly becoming more accessible to markets, and there is every indication of a strong future demand at greatly increased prices. On nearly every tract, a second cut can be made within thirty years. All marking under present sales should be done strictly with reference to two points:

"1. Stocking the cut-over land as fully as possible with sugar and yellow pine.

"2. Securing a second cut within thirty years.

"All cutting should be done under the 'selection system,' which requires a careful choice of the individual trees to be removed.

Fixed diameter limits and the leaving of any specified number of seed trees per acre can be very largely disregarded.

"The condition of every sugar and yellow pine on the sale area should be studied closely to determine whether that tree will be merchantable thirty years hence, by which time a second cut is probable. As a rule the trees which will remain merchantable for another thirty years should be left. Suppressed and crowded trees which cannot develop should be removed. Under this system of marking, ordinarily about one-half of the present stand of merchantable pine would be left uncut. Will it pay?

"On areas where practically all of the pine is over-matured and would be cut under the rule given above, a sufficient stand must be left to reseed thoroughly the cut-over land. This requires not less than four full seed-bearing trees, at least 25 inches in diameter, per acre. The strongest and thriftiest trees available should be selected for this purpose, but not less than the number specified must be left even if every tree will be a total loss before a second cut is possible.

"Extensive areas of pine timber which are not yet fully mature should be excluded from the sale. On patches or small areas of immature pine, which it is not practicable to exclude from the sale, cutting should be very light, limited to one-third or less of the largest trees, or omitted altogether.

"No attempt to discriminate sharply between sugar and yellow pine should be made, as both trees are almost equally desirable. Where a choice is necessary, sugar pine should be favored on moist situations, as in canyons, moist pockets, or benches and on northerly exposures.

Yellow pine should be favored on dry situations, including exposed ridges and southern exposures.

"Fir and incense cedar should be marked, as a rule, to as low a diameter as these trees are merchantable in order to reduce the proportion of these species in coming reproduction. It is essential, however, that no large openings be made in the present stand since the exposed ground is in danger of reverting to chaparral or of becoming so dry from evaporation that no reproduction will follow cutting. Where the stand of pine is insufficient to reseed thoroughly and protect the cut-over area, enough sound, thrifty fir and cedar should be left to form a fairly even cover with openings less than a quarter of an acre in size.'"

The under current of all opinion upon sugar pine up to date is that reproduction will not be very successful unless enough growth to shelter the seedlings remains after logging. Where the fire risk permits, the same end may be furthered by leaving the tops scattered on the ground.

Little experimenting has been done in planting sugar pine, but there are many indications that except where conditions strongly favor natural reproduction it will be resorted to eventually if any particular attempt is made to get this species. Leaving large seed trees is not only expensive, but rather uncertain, because heavy seed years are several years apart and squirrels consume a large portion of an ordinary crop. Transplants which have received nursery shelter until past the greatest danger of drying out should prove most successful on heavily-cut south slopes.

REDWOOD (_Sequoia sempervirens_)

Although probably the most rapid-growing of all American commercial trees and also of high market standing, redwood has been little studied by foresters. The layman is still more confused by its many peculiarities. Growing to a size of 20 feet in diameter and 350 feet high, reaching an age of well over 1,000 years and seldom reproducing by means of seed, it is not surprising that it was long regarded as ill-adapted to second crop management. Although observing that suckers sprout from the stumps with great rapidity, the lumberman generally regarded these mushroom growths as abnormal and temporary, and believed his virgin timber to be the finally-vanishing remnant of a prehistoric species unsuited to present-day conditions.

It was next discovered that the suckering habit is no new one, indeed that the majority of the present stand, however old, began as sprouts from roots or stumps of its predecessors. This is evident from the circular arrangement of several trees around the spot where their parent stood. These old sprouts were of very slow growth, for they were shaded by a forest of extreme density. As seedlings they could have neither germinated nor grown, but as suckers they were kept alive by the parent until light supply became available through their increasing height or through thinning of the forest.

Under such conditions centuries were required to produce large trees.

The owner of today, by cutting down the old stand, gives the suckers conditions. .h.i.therto unknown to the redwood. The vigor and susceptibility to the aid of light, which originally was necessary in the sprout growth to perpetuate the species at all, now respond to entire freedom and light in an astonishing manner. Even after severe slashing fires char the stumps, the latter throw out cl.u.s.ters of sprouts which grow several feet a year. Logging works 30 or 40 years old have come up to trees nearly 100 feet high. Naturally such timber has a heavy percentage of sapwood and is soft and brittle, but it is already suitable for piling, box lumber and like purposes and improves constantly.

Since reproduction by seed does not enter into the problem, financial possibilities depend almost wholly on the nature of the original stand. There are many types of redwood forest, pure and mixed, flat and slope. If the old trees are few to the acre, the sprout cl.u.s.ters will be so far apart that excess of side light will produce clumps of swell-b.u.t.ted, short limby trees, of little use for lumber; that is, unless there is also a seedling growth of fir or other species to fill the blanks and bring up the density. Where such a nurse growth is to be counted on, or where the redwood trees are small and close together, ideal conditions for a certain, rapid and well formed second crop exist.

The thinner the original redwood stand, the greater the effort necessary at the time of logging to obtain the required density. The leaving of seed trees of other species, with as many as possible small trees of both redwood and other species and the maximum protection of all from fire, should then be the means employed. On some tracts the proportion of redwood will not warrant this effort; on some it is not even required. The question of whether it pays to hold redwood land is therefore almost wholly local, but when conditions are favorable it can be answered affirmatively, because of the extremely rapid growth, with less doubt than of almost any other species.

There is some tendency to over-production of sprouts by redwood stumps. Removal of the excess with an ax, saving those closest to the ground and not over-thinning to the extent of reducing the density conducive to height growth and shedding of low branches, improves the chances of those remaining.

SEEDING AND PLANTING