Prolonging the cut of southern pine

Part I. Possibilities Of A Second Cut

By Herman H. Chapman, Professor of Forest Management

PART II. CLOSE UTILIZATION OF TIMBER By Ralph C. Bryant, Professor of Lumbering New Haven

Yale University Press

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Bui. 2, Yale Forest School

Plate I

STUDENTS OF THE YALE FOREST SCHOOL CRUISING TIMBER IN A TEXAS SHORTLEAF

PINE FOREST

Issued April, 1913

Yale University

YALE FOREST SCHOOL— Bulletin 2

PART I. POSSIBILITIES OF A SECOND CUT

By Herman H. Chapman, Professor of Forest Management

PART II. CLOSE UTILIZATION OF TIMBER

By Ralph C. Bryant, Professor of Lumbering

New Haven

Yale University Press

Contents

Part I. Possibilities of a Second Cut

Page

Introduction 1

Introduction

Since 1907 the Yale Forest School has conducted the field work and instruction of the Senior class in the spring term in cooperation with lumber companies located in the southern states. The companies which have extended this cooperation are:

1907, Missouri Lumber and Mining Co., Grandin, Missouri.

1908, Kaul Lumber Co., Hollins, Alabama.

1909, Thompson Brothers Lumber Co., Doucette, Texas.

1910, Louisiana Central Lumber Co., Clarks, Louisiana.

1911, Thompson Brothers Lumber Co., Trinity, Texas.

1912, Crossett Lumber Co., Crossett, Arkansas.

1913, Southern Lumber Co., Warren, Arkansas.

In no case has there been a formal contract between the company and the School, but under verbal agreement the company has allowed the students the freedom of its mills and lands for purposes of instruction, built temporary wooden shacks for quarters in camp, instructed its employees to give such information as will be of assistance in instruction in logging and milling, and furnished commissary supplies at reasonable prices. The students maintain their own commissary in camp and pay all their own expenses.

The work is conducted primarily with the object of instruction, but a large amount of information is collected and given to the company. This consists of a topographic map, an estimate and description of timber and young growth, data on the growth of the timber, suggestions for management of the tract for the production of wood, and studies of present utilization and waste in logging. It has been possible so to combine training and practical work that although prepared by comparatively inexperienced students, the data and maps obtained have shown a creditable degree of accuracy and have in most instances proved of considerable value to the company.

The tract studied in the spring of 1912 at Crossett, Arkansas, is exceptionally well adapted to forest growth, and illustrates in a striking manner the possibility which presents itself to lumbermen throughout the South of modifying their methods of logging so as to get a second cut. During the six years of investigation in different southern states, the School has ascertained that probably over wide areas of longleaf and shortleaf pine the stand should be only partially removed in the first operation, leaving a fairly large percentage for a second cut in from fifteen to twenty years. If properly carried out this policy will secure a satisfactory rate of interest on the value of the timber left standing. This will be attained by rapid growth in volume and advance in stumpage values. Apparently it does not involve great expense at the present time.

PRESENT POLICY IN THE SOUTH

The present policy of most holders of stumpage in the South is clear cutting, which is followed by accidental or intentional broadcast burning of the slash, and sale of the land to settlers or land companies ; and this is attempted in spite of the fact that there is at present no urgent demand for much of this pine land and that these timber companies still have ten to thirty years' cut in sight.

A few farsighted firms have attempted in places to limit the present cut to a certain diameter, reserving the small trees for a future crop. This is a move in the right direction, yet analysis shows that adherence to such a rigid diameter limit does not leave the most vigorous trees. It is not good business deliberately to leave an investment in the woods and secure only 3 per cent increase when, with the proper supervision, 6 or 7 per cent might be obtained on the same capital, yet that is just what is being done by most operators who are planning on a second cut. The others are neglecting an opportunity to prolong their business, lessen their annual depreciation charges, and secure future increase in stumpage values.

Clear cutting may be justified by the relative inaccessibility of the tract, making it unprofitable to return for a small second cut. Again, the land may be needed at once for agriculture, or the stumpage may be purchased without the land and require cutting clear. In most instances, however, this practice is due to lack of confidence in the methods demanded and absence of authoritative information as to the growth and financial returns obtainable by leaving a stand for later removal.

While actual demonstration of results is the most convincing argument, it requires that some companies make the attempt, else the time will come when there will no longer be an incentive to existing firms to cut conservatively. A mill with twenty years' cut ahead is in better position to try out the plan than one with but five years to run. Even without such a demonstration it is possible to predict with fair accuracy the growth that will occur after cutting and to outline measures which will assure a second crop.

REPORT ON LANDS IN ASHLEY COUNTY, ARKANSAS

The report of the Class of 1912, Yale Forest School, to the Crossett Lumber Company, on their tract in Ashley County, Arkansas, is presented herewith. This report deals with local conditions. Previous work of the School in Louisiana and Texas indicates that similar conclusions may be drawn for the better and more accessible areas of longleaf and shortleaf pine throughout the South.

MAPPING THE TRACT

The area covered by this report includes approximately 27,000 acres lying south of Crossett, partly in Arkansas and partly in Louisiana. The greatest difference in elevation is about 150 feet and the country is either flat or gently rolling, with occasional abrupt slopes. Logging roads can be laid out with little regard to topography. This greatly lessens the value of a topographic map, but for purposes of instruction one was prepared on a scale of 2,000 feet to the inch, with horizontal contours showing 5-foot differences in elevation. Upon this map streams, dry gulches and roads were shown.

The timber areas were plotted on the map in distinctive colors, according to character of stand. The stands shown are as follows :

(a) Mature pine timber chiefly of large size with insufficient young timber to justify a second cut.

(b) Pine timber of all ages containing enough young timber to justify a second cut.

(c) Brush land with hardwoods and scattered pine averaging less than 1,000 feet b.m. of pine per acre.

(d) Cut-over pine land with practically all mature pine removed.

(e) Pine in old abandoned fields, usually a dense stand.

(f) Hardwood lands, usually bottomland with little pine.

In addition to the areas mentioned above, cleared lands under cultivation or in pasture are shown.

ESTIMATE AND DESCRIPTION

A timber estimate and full notes on the stand were made for the area covered by the map. The work was done by the students after eight days of training in timber estimating, and allowances must be made for lack, of experience and for variation in individual ability of the men. The method used was to count the trees in strips on half the area, correcting for differences in the stand where the timber stood unevenly on the remainder. One-third of the counted trees were measured by eye and tally kept of diameters and of the number of logs in each tree. The contents of these trees in board feet was derived from a table prepared from 300 felled trees on the tract. The stand on each "forty" was computed from this count and tally.

A percentage was deducted for loss from rot, and where there was damage from insects or windfall it was stated in percentage of the standing timber. The character of the merchantable timber was briefly described with reference to the size of the logs, clear length and percentage of grades under "uppers," "No. 1 common," "No. 2 common," and lower grades, thus giving some idea of the relative value of the timber. The quantity and character of small or immature timber was noted, including its size and age and the area covered. The purpose of this description was to record the conditions on each "forty" so completely that no further examination would be necessary for any purpose.

COMPOSITION OF THE FOREST

The pine timber on this tract is composed of shortleaf and loblolly pine in almost equal mixture. This fact is unimportant from the market standpoint, because the two species are of practically equal value and not easily separated when manufactured into lumber. Loblolly grows almost pure on the lower flats and frequently forms pure stands on abandoned fields. It gradually gives place to shortleaf on drier soils and on the driest the shortleaf grows pure.

Pine forms almost pure stands on all the higher lands. It has the ability to resist droughts, which are frequent and severe during the growing season, the months of April, May and June.

The droughts seriously interfere with the development of hardwoods on these soils and the only hardwood growth is a few very stunted and deformed oaks from which some timber is cut. Better hardwoods, including white and black oaks and some sweet gum and hickory, appear near streams where the soil is fairly well drained, moist and deep. The true hardwood stands occupy the bottoms, which are subject to overflow and where there is comparatively little pine reproduction. These lands were under water in the spring of 1912 during the unusual floods of that year and were not examined.

DAMAGE

The mature pine is fairly sound. Old stands show a large amount of red rot and a lesser amount of butt rot, although the cull seldom exceeds 10 per cent of the volume on any "forty" and averages less than 3 per cent.

Fire has done very little injury to the timber. A small percentage of the trees show scarred butts, often due to the burning out of faces chipped off to test the grain for shingle bolts. Most of the timber is sound at the base and escapes injury from ordinary surface fires.

The greatest loss to the timber results from wind. This is due to the soil, which in many sections is underlaid with hardpan from two to five feet below the surface, into which the tap root of the pine cannot penetrate. In consequence the tree is entirely dependent on the spreading lateral roots for its support. In very wet seasons, like the spring of 1912, the soil becomes quite soft. Often a heavy wind will uproot many trees. Some sections are more subject to wind damage than others and, through repeated losses, the forest there has assumed a clump-like, manyaged form. This condition is doubtless due to the presence of hardpan nearer to the surface than on the tracts showing less windfall. Tornadoes are very rare, although there have been one or two instances of very heavy loss over a limited area, necessitating immediate logging. More often scattered single trees, including young, small poles as well as older and larger timber, will go down here and there. Weak roots and resulting poor anchorage, rather than undue exposure to wind, seem to determine which trees blow over.

Insect damage is present on almost all sections examined. The bark-boring pine beetles (Dendroctonus sp.) are continually killing trees, both among the old timber and crowded young stands. Occasionally 5 per cent of the trees may be killed within three or four years. The insects first attack trees which are sickly or weakened and those tend to become centers of infection. If conditions are favorable, the insects may increase very rapidly and destroy the pine timber over wide areas. Under ordinary conditions their natural enemies, such as woodpeckers, keep the insects from doing excessive damage. Areas badly infested with beetles should be logged as soon as possible in order to lessen the danger of the beetles spreading to adjacent areas.

AGE CLASSES

The age of the pine timber in this vicinity rarely exceeds 150 years, although occasional very old trees may reach 200 years. Much of it is approximately even-aged, but seldom continuous over very large areas. It is more likely to be broken up into different age classes, clumps of large, overmature trees being interspersed among groups of young timber, small poles or seedlings.

On much of the pine land old timber occupies the soil to the exclusion of young growth. The spread of the roots of very large trees is much greater than that of their crowns, due in part to the great demand of old trees for moisture. Owing to this wide spread of the roots, old stands, even when fairly open, do not contain much young timber until the old trees begin to disappear from weakness due to rot, or destruction by insects, wind or lightning. The final form of such a stand is a few scattered old trees of large size in a forest of young timber of various sizes and ages.

REPRODUCTION OF PINE

Pine seedlings spring up readily everywhere, provided the seed reaches mineral soil. Surface fires are a great help in preparing a suitable seedbed. Seeds seldom, if ever, germinate on pine litter or hardwood leaves and not readily in grass. Abandoned fields that have been cultivated afford an excellent seedbed, but old pastures reforest very slowly. The conditions after logging, where the ground has been torn up by skidding, are excellent for pine reproduction. The only reason there are not more seedlings in the forest before logging is that they cannot live under the old timber. They often require more light than is available, but the most important factor is the soil moisture. The seedlings are killed in dry seasons by the old trees, which deprive them of moisture. Reproduction on cut-over lands is either destroyed by fire or prevented from starting through lack of seed trees.

Old-field stands constitute an important part of the forest. Many of them are about forty-five years old and already large enough to cut. These stands are dense with sixty to eighty trees per acre, and the timber is frequently very limby because it has grown on open fields and with full crown development. This and the rapid growth of the timber reduce the quality and make it a poor logging proposition compared with the better grades and sizes of the older timber. These old-field stands will, in time, however, yield large crops of timber and of very good quality. A large percentage of the trees are, through crowding, already cleared of branches and from now on will, if thinned out, and the remaining trees given room to grow, add clear material at a rapid rate. At present many old-field stands are so densely stocked that the trees are making slower growth than they should.

GROWTH OF PINE

The rate of growth of both shortleaf and loblolly pine in this locality is rapid; it exceeds that found elsewhere the School has studied it.

Table 1. — Average Growth in Diameter Breast High Outside

Bark of Shortleaf and Loblolly Pine in

Ashley County, Arkansas.

(Basis 200 Trees)

Age, Years.

Diameter,

breast high.

Inches.

Table 1 gives the average diameter outside the bark at breast height (41/0 feet) of trees of different ages from 10 to 100 years. It is based upon the measurement of 200 trees.

Since these species grow in mixture over most of the tract, it was thought best to obtain an average figure for both species rather than to determine the growth separately for each.

This rate of growth of about an inch every four years during the first forty years or an inch every five years for the entire 100 years is for average trees, and shows that timber reaches merchantable dimensions from seed in from forty to fifty years. This is borne out by the growth of old-field stands. Six plots of five acres each measured in old-field stands showed yields of from 7,500 feet b.m. to 14,200 feet b.m. per acre, with ages from forty to forty-seven years. The more rapidly growing trees reach merchantable size in thirty years and old-field stands will yield 2,000 to 3,000 feet b.m. per acre when thirty-five years of age. In the next few years the yield of merchantable timber rapidly increases as the trees attain merchantable size.

Table 2. — Average Yield per Acre of Even-Aged Stands of Shortleaf Pine, Under Ordinary Conditions, on Large Areas in Ashley County, Arkansas.

(Doyle Rule)

Average

Age of Stand,

Yield per Acre,

Growth per

Years.

Board Feet.

Year, Board Feet.

6,000

6,600 no

8,100

9,600

11,000

12,400

13,600

14,800

15,800

16,600

17,200

Dense stands with a large number of trees per acre, such as occur on old fields, cannot maintain both numbers and rapid growth. The increasing demands of larger trees for soil moisture during the growing season cause the number of trees which can continue to thrive on an acre to diminish rapidly. When most of the trees are of nearly the same age and height, the crowding out of the weaker trees does not take place as rapidly as it should, and the growth of all the trees may be seriously retarded. In the ordinary forest the same crowding and loss of numbers occur, but the more broken and irregular character of the stand makes it less pronounced. Under average conditions yields of timber can be depended on to equal or exceed the results given in Table 2.

In fact, better yields per acre than this are obtained in the virgin forest on many "forties," and with any sort of management which secures good reproduction and affords protection, these yields should be increased by one-half, as is shown by the yields actually obtained on old-field stands. In other words, these are in no sense maximum yields, but may be obtained under almost any circumstances and without expensive measures.

These yields, shown in Table 2, may be increased from 50 to 100 per cent under proper management.

MANAGEMENT OF THE TRACT

The company desires to maintain as long as possible the present output. The estimate of merchantable timber indicates a cut of approximately eighteen years. The company believes that growth and the increase on old-field stands will extend the cut two years. The depreciation charge and investment in the plant have, therefore, only twenty years to run. If it can be shown that, by a different procedure, growth may be more fully utilized and the cut extended even two or three years, this policy would have much to recommend it from a financial standpoint.

AGRICULTURAL POSSIBILITIES

The land will not be kept permanently in forest by the present company and it is planned ultimately to dispose of it as farm lands. Old settlers do not consider the pine ridges suitable for continuous cropping and favor the lower lands, not overflowed, along small streams. These soils have better depth, more loamy texture and produce fair crops of corn, cotton or cane, while the pine ridges are likely to dry out and result in crop failures. With proper fertilization, improved methods of cultivation, better markets and the advent of truck crops, small fruits and orchards, much of this land will prove valuable for agricultural use.

The company is probably pursuing the proper policy in planning to dispose of the entire tract at some future time. But this by no means proves that it is unwise to encourage a crop of seedling pine on cut-over lands. In twenty years such seedlings will be five inches in diameter and with increasing scarcity of pine, and the small percentage of lands elsewhere that are coming up in young forest, this small timber will give the land a prospective value that may equal or exceed its value for agriculture and would aid greatly in its sale. By that time purchasers will be keenly alive to the value of young timber on land, even if desired for agriculture. Such portions of the farm as are not under cultivation should be in growing forest.

SECURING A SECOND CUT OF PINE

The desire of the company to secure some return from growth has taken the form of instructions not to cut trees smaller than fourteen inches on the stump, equal to about twelve inches breast high. The carrying out of this rule is left entirely to the sawyers, under the rather hurried and indifferent inspection of the team boss. The method is an almost complete failure, for the following reasons :

(1) There is lack of proper inspection of the saw crews, who do practically as they please about taking or leaving trees.

(2) A diameter limit is wrong in application as it removes young, thrifty, rapidly growing trees if over fourteen inches and leaves standing tall, slender, poor-crowned old trees of very slow growth which ought to be cut.

(3) Trees are not selected for wind resistance and many trees so left will blow over because of weak roots.

(4) In stands of overmature timber often there are virtually no trees below fourteen inches in diameter that are suitable to leave.

(5) At present, trees left are not adequately protected from destruction by fires which consume the tops and debris after logging. They are apt to be a total loss from this cause.

(6) While leaving this nucleus for a second cut, no effort is made to protect smaller timber, which is often smashed in felling, slashed down for skids to support temporary spurs in wet weather, and burned by slash fires.

The sawyers are under instructions not to fell trees onto groups of small timber, but inspection is necessary to secure proper compliance with this or other rules.

CONDITION OF THE CUT-OVER LANDS

The condition of the cut-over land is at present very unsatisfactory. Only in widely scattered, occasional patches is enough young timber found to pay for a second operation. Elsewhere there has been practically no timber left standing and severe fires have burned the slash, destroying the immature pole timber. In places a dense crop of seedlings has sprung up, but over the greater portion of the cut-over lands fires and the lack of seed trees have prevented a new growth of pine, and only grass, worthless oaks and scrub sweet gum are coming in.

PROPOSED PLAN FOR SECURING A BETTER SECOND CUT

The company should either abandon the plan of leaving trees below fourteen inches in diameter or it should adopt an entirely different policy involving the selection of the trees to leave and the proper handling of the fire risk. The latter policy appears best, provided it can be shown that it is comparatively simple to enforce and that it will result profitably. This involves the following essential points :

(1) Stands net suitable for a second cut should be cut clear unless a few seed trees are left to restock the land.

(2) In stands which contain suitable young timber the trees to be removed should be marked and no others should be cut.

(3) Proper disposal of the tops must be secured under inspection to eliminate the fire risk and preserve the timber left standing.

RESULTS OF EXPERIMENTAL MARKING FOR A SECOND CUT

To present the subject concretely, certain areas were mapped and separated into (a) those upon which the timber was mature and not suitable for a second cut, and (b) those which were well adapted to a second cut because they contained young timber. The mature stands from which it will be difficult to secure a second cut were marked so as to leave for seeding purposes only healthy, rapidly growing trees as small as possible, which would stand until, the next cut twenty years hence. This policy is not recommended except where the company decides that the securing of a complete stand of seedlings on the cut-over lands will justify the present expense.

On 200 acres so marked, the stand averaged 14,000 feet b.m. per acre, or 560,000 feet b.m. per "forty." By proper selection the seed trees selected contained 1,050 feet b.m. per acre or 42,000 feet b.m. per "forty," which is 7.5 per cent of the stand. The total number of trees per "forty" was 800, or 20 per acre ; this would be reduced by the proposed cut to 150, or 3.75 trees per acre, which is 18 per cent of the whole number. It is evident from this that comparatively small trees were selected. The growth added to the seed trees will, because of their size, probably be between 2 and 3 per cent a year, or a possible 200 to 300 feet b.m. in ten years. In twenty years, the yield from these trees would probably be increased to 1,500 feet b.m. per acre. The actual sizes taken and left in each inch class on an average forty acres containing 810 trees are shown in Table 3.

Table 3. — Stand of Timber on an Average Forty Acres of Mature and Old Shortleaf and Loblolly Pine in Ashley County, Arkansas, Showing Total Number of Trees, Those to be Removed, and Those That Would Remain.

Diameter,

breast high,

inches.

Total No. of

Trees to be

Trees to be trees.

removed.

left standing.

—

—

—

—

—

—

—

—

—

—

—

—

—

Over

—

Number of Trees Left.

118 34

On areas adapted to a second cut, tabulation of actual marking on 200 acres shows the following results: average stand per acre, 8,129 feet b.m. ; on forty acres, 347,292 feet b.m. ; average stand per acre to be left after cutting, 1,805 feet b.m.; on forty acres, 79,300 feet b.m. Thus 22.2 per cent of the stand or 1,800 feet b.m. would be left as against 7.5 per cent or 1,050 feet b.m. in mature timber. The younger stands contained 1,051 trees 12 inches and over, "breast high," on an average "forty," or 26.2 trees per acre. Stands composed wholly of young timber would have about 50 trees per acre. In the mixed stands, 457 trees would be left on a "forty" or 11.4 trees per acre, which is 43.5 per cent of the total number but only 22.2 per cent of the volume. How wide a departure from the rigid diameter limit the proper selection of trees makes is shown for an average "forty" in Table 4. In the method of individual selection it is seen that about one-third of the trees below 15 inches, one-half of those between 15 and 17 inches, and practically all 20 inches and over are to be removed. A few above 20 inches are to be left to provide seed for openings made by cutting large groups of old timber. They can be removed in the first cut if thought best.

Table 4. — Stand of Timber on an Average Forty Acres of Mixed Young and Mature Shortleaf and Loblolly Pine in Ashley County, Arkansas, Showing Total Number Trees to be Removed and Those That Would Remain.

Diameter,

Total No. of

Trees to be

Trees to be breast high.

trees.

removed.

left standing.

—

—

—

—

—

—

—

—

—

—

—

—

Over 40

—

1,051

Number of Trees Left.

435 22

Total

NECESSITY OF MARKING TREES TO BE CUT

It is necessary to mark the trees to be cut instead of depending on an arbitrary diameter limit for the following reasons:

(1) Windfall. Opening a stand greatly increases the danger of windfall. Trees differ greatly in their wind resistance. Those growing in crowded clumps have weak roots, while thrifty trees growing in partial openings have well-developed roots. By selection of wind-firm trees to be left the danger of windfall in the remaining stand may be reduced to reasonable proportions.

(2) Growth. The purpose of leaving these trees is to secure growth which should be as rapid as possible. But trees differ remarkably in their rate of growth, a fact that can be verified by cutting into a few at random and counting annual rings of growth in the last inch of radius. The trees best to leave for the second crop are those making the largest growth per cent, based on the present volume of the tree. A small thrifty tree makes a higher growth per cent than a large tree because the volume of the former is less at present and the relative increase is much greater. The character of the crown indicates the vigor of the tree, since the growth is directly dependent on the amount of foliage, which, in turn, is determined by the available light and root space. Rapidly growing trees are sure to have thrifty, large and well-developed crowns. This can be told at a glance after a few days' practice.