Department of Agriculture and Immi- gration of Virginia GEO. W. KOINER, Commissioner In co-operation with the Forest Service United States Department of Agriculture HENRY S. Gravk&s, Forester SHORTLEAF PINE IN VIRGINIA The Increase in its Yield by Thinning By W. W. ASHE Forest Examiner, Forest Service RICHMOND: DAVIS BOTTOM, SUPERINTENDENT PURLIC PRINTING 1913 TE I. PLA Crowded small pole stand of shortleaf pine about 30 years old in need of stemmed A large gular in size. but irre ’ The trees are slender and clean num ber of the smaller trees should be removed. thinning. Department of Agriculture and Immi- gration of Virginia GEO. W. KOINER, Commissioner In co-operation with the Forest Service United States Department of Agriculture HENRY S. GRAVES, Forester SHORTLEAF PINE IN VIRGINIA The Increase in its Yield by Thinning By W. W. ASHE Forest Examiner, Forest Service RICHMOND: DAVIS BOTLrOM, SUPERINTENDENT PUBLIC PRINTING E 1913 By Tranefer SEP do (gl iz CONTENTS GVO Siac CmereSUNES beg 27.5.) sym athe alele ai Sate ate eucenens anit vue kis apne Stn oe 5 eM uNEUOMR AM Ge LID OT CAIICEs «oye ws ites so Ss nope lentes and! Spo dads ow duereeres = 6. Nameseandeadistineuishines characteristics... (..ccmce +. ss -%l se: % RSC See OlemWViOO Obieety-narpres. © cues tne Petsna csc k oy its Saucy Re Hae yelat at's eis eels See & Condiivoneand Composition, of old-field standS:..:................. 2 Eeniianeney sor Old-neld apintesstands=. .:20..-seleee ss. cee eee 10: Management ...... Tie iy Card SG, PURSE AEP NORE GENET PPRLELUADS I er POAT eg Si Me De REY ae 12 Fully stocked and crowded stands...................: Sn peter Sts ilps A DIT CEREOCK COs eS ANOS: iicic iid cetaeietecce)t « ars.cnecepd aly ss soo a wrens 14. | “LUTTE STTDSHS 8 8 eRe corey eRe IE Oe le gc 3 ee 1b, WIASSCSmO CL COSI Reeth) Mee ein Bais, anne acs ea anced nate iets 15 ROTA UEC Sie eters mene tae Wet Wes ee, ueeausyaa Bayne Panna. 15 | IMBC TMC A UCHR UTC CSU Parnes ct rosy) ake aie Shere eiave eres coe 15 | STIMURCSSCOMBULCCSER ROM: © eh e 2 Ua ene or hge nen eee Soe he 16 | EMU REG vee CONC ITs ta Reno Peer oo toate 4h Tinsatigs Vy oi oingotec un Scr eee > NGS sc ern ee? ae kw 43 BUN EUS a dISCASES. = an: ae aey.cieeee re = 3 PE hc coors 44 ILLUSTRATIONS Plate I.—Crowded small pole stands of shortleaf pine about 30 years old in need of thinning. The trees are slender and clean stemmed, but irregular in size. A large number of the smaller trees should! she; removeds okie. 2% 2: ties eee ee es eee Frontispiece. Plate IIA dense sapling stand of shortleaf pine 15 to 18 years old, but too small to be profitably thinned. While the clean condition of the floor is good, fire could do great damage to such a stand Plate IIJ.—Understocked large pole stand of shortleaf pine 30 years old. The trees are short-bodied and knotty and will yield only low grade lumber. The best that can be done with such a stand is to cut it, leaving the most slender, clean-bodied trees for seed-trees Plate IV.—Crowded, large pole stand of shortleaf pine 40 years old, badly in need of thinning by removing the smaller pines and many of the hardwoods. Condition of larger trees, with long, smooth bodies, excellent. Plate V.—Mature stand of shortleaf pine. Trees nearly uniform in size and ready to be cut for lumber. Groups of slender, wind- firm trees can be left: for seed trees. Plate Vi.—Figure 1.—A typical case of sustained rapid diameter growth, resulting from repeated thinnings, in a tree of short- leaf pine which was overcrowded for many years. Wood of ssuch a tree is free from large knots, and its stumpage is -worth $8 a 1,000 board feet under a cost of operating of $12 Figure 2.—Stem of a small sprout sapling of shortleaf pine, crooked and scarred at the neck as a result of the original ‘seedling having been killed to the ground by fire. Stump and ‘root rots gain entrance through such scars. Shortleaf Pine in Virginia The study upon which this report is based was undertaken by the Forest Service in co-operation with the State of Virginia, the work being done under the direction of the officer in charge of State Co-operation in the Forest Service. By the terms of the co-operative agreement, the State is authorized to publish the find- ings of the investigation. PURPOSES AND RESULTS. At the request of Hon. C. A. Swanson, Governor of Virginia, the Forest Service, United States Department of Agriculture, in the autumn of 1909, made an examination of the second-growth shortleaf pine in old fields in the middle portion of Virginia. The cost of this work was borne jointly by the State of Virginia and the Forest Service. The examination included a detailed investigation of stands of pine in old fields in Mecklenburg, Lunenburg, Brunswick, and Hanover counties, which was supplemented by a general examina- tion of the stands in other counties in the middle part of the State. Its scope was: (1) To ascertain the condition of the old-field stands and the ralue of thei timber for lumber uses; (2) To determine the effect of lumbering on the future yields of the stands and to ascertain whether conservative methods of cutting could be employed profitabLy ; (3) To determine the yield of stands of different ages; (4) To recommend methods of thinning and cutting to ac- celerate growth; (5) To devise methods of protection for young growth. The conclusions reached as a result of the investigation can be summarized as follows: Shortleaf pine is the most important tree in twenty south- central counties, but the yield from the pine lands is low because there is neither protection nor a definite system of cutting. The yield can be greatly increased and the quality of timber improved by a regular system of management. (1) Better protection against fires and insects is required in most stands. Young stands, especially while in process of stocking, 6 SHORTLEAF PINE IN VIRGINIA suffer most from fires. Older stands are most endangered by in- sects. Protection against fire may be secured by means of fire lanes, posted warnings, restriction of night hunting, and patrol during dry seasons when neighboring lands are afire: The danger of loss from insects may be reduced by making frequent thinnings and by removing or by cutting infested trees. (2) The average stand of pine is far too thinly stocked. ‘This is due to insufficient natural seeding and to the thinning of young stands by fire and of older stands by insects. The yield of such thinly-stocked stands is considerably less, and the grade and value of the timber is lower, than from thickly stocked stands. (3) Crowded areas occur in nearly all stands, and some stands are crowded throughout. Such crowded plots can be greatly im- proved by thinnings. The effect of thinnings is to accelerate growth, hasten maturity, and produce a superior quality of timber. The beneficial results of thinnings decrease with the age of the stand, but stands as old as forty-five years respond. to them well. (4) Where natural seeding has not formed dense stands with- in ten years, the stocking can be completed by the planting of seed; and, where natural seeding does not take place, whole areas may be seeded. Stands restocked in these ways can be expected to yield fully as well as the best natural stands and to return a fair rate of interest on their cost. If management is applied, that is, if young stands are pro- tected, full stocking secured, and the stands subsequently thinned, the yield of saw timber from a 40-year-old stand can be more than doubled and its value greatly increased. Shortleaf pine is already one of the chief sources of building material on the farms. Fur- thermore, the farms have more timber than is required for their own support, so that as the general demand for coarse lumber 1n- creases and its price rises, shortleaf pine in farm woodlots can be made an important source of commercial timber and a means of - permanent income. DISTRIBUTION AND IMPORTANCE Second-growth or old-field shortleaf pine is the most important tree of middle Virginia and the Piedmont, south of the Rappa- hannock, in which region it probably cccupies more than one-half of the total forest area and more than three-fourths of the farm forest area. It forms the dominant growth on more than 3,000,000 acres, on which it occurs either in. pure stands or, more commonly, SHORTLEAF PINE IN VIRGINIA i with a shght mixture of other pines and of seedling and sprout hardwoods. It meets with least competition and forms the purest second-growth stands in the tier of southern counties west of Lun- enburg county. It is not common north of the Rappahannock river, and is infrequent on the Blue Ridge mountains and in the Great Valley, while in Tidewater Virginia it grows only on the best drained clay soils, and in these sections, on account of the com- petition of other species, its second growth seldom occurs in pure stands. NAMEs AND DisTINGUISHING CHARACTERISTICS Shortleaf pine is also and more generally known as rosemary pine, spruce pine, and yellow pine. The original growth is fre- quently distinguished from the second growth in old fields under the names of forest or woods pine. This tree is not to be confused with scrub or jack pine, which is also called spruce pine. Scrub pine is a smaller and in- ferior tree with a limby stem and smooth, scaly bark. It is largely replacing shortieaf pine in old fields in the northern portion of the State and in the upper edge of the Piedmont in and near the mountains, and is occasionally found mixed with shortleaf pine southeastward as far as Brunswick county. Nor is it to be con- fused with loblolly pine, which is known in extreme southern Vir- ginia as shortleaf pine and, where it occurs near the coast, as long- leaf, swamp, foxtail, or slash pine. Loblolly pine is the common pine on sandy soils in Tidewater Virginia, but it extends westward in association with shortleaf pine to Brunswick, Chesterfield and Louisa counties. The northern pitch, bull, or black pine of the mountains, which is yet another tree, seldom forms second growth in old fields. The cone and leaf differences of these trees will be a further help in separating them: Shortleaf pine has cones (burrs) seldom more than 1 1-2 inches long, and slender, straight needles, two or three together, twice as long as the cones. Serub pine has cones of about the same length as those of shortleaf pine (1 1-2 inches) but they are relatively broader. The needles are stout and twisted, with never more than two together, and are about the same length as the cones. Frequently the cones of scrub pine and shortleaf pine remain on the trees for many years after opening. 8 SHORTLEAF PINE IN VIRGINIA Loblolly pine has large cones, from 3 to 4 inches long. Its needles are borne in threes and are about twice as long as the cones. The cones of this species usually fall during the second summer, but sometimes they persist for several years. Uses or Woop The timber of second-growth shortleaf pine is largely sap- wood. The formation of heartwood does not begin until the trees are about twenty-five years old. For many years thereafter the heartwood is limited to a small core, and more than two-thirds of the volume of trees fifty years old is still sapwood. The most im- portant uses for the wood of the shortleaf pine are for building lumber, fuel, slack cooperage, box lumber, headings, and crates. The wood contains too much resin to be a desirable material for paper pulp stock without special treatment, although it is used to some extent for this purpose. On account of its softness it is not suited for railroad ties if the traffic is heavy, and, when used for this purpose should be made more durable by preservative treat- ment. The large proportion of sapwood in the second-growth tim- ber renders it undesirable for shingles, for which the durable heart- wood of the old growth was extensively employed; and unfits it for other uses requiring exposure to the weather, unless it is thoroughly kiln-dried and painted. Logs more than fourteen inches in dia- meter from trees with clear boles yield lumber suitable for ceiling styles and panels of doors, sashes, window frames, interior wood- work, and also for flooring if rift sawed. Timber suitable for such uses must come not only from comparatively large trees, but from trees which early cleaned their stems and formed wood in the lower two-thirds of the trunk free of knots. That part of the tree which can be converted into lumber of this kind should command, on the basis of $25 for the finished lumber, a stumpage price of not less than $10 a thousand board feet. Unless the price of cordwood stumpage is proportionately much higher than that of saw timber stumpage, the greatest profit from a crowded stand will be secured by reserving the larger trees for saw timber, and in the meantime thinning or culling the small- est trees for cordwood, stave stock, box boards, bolts, and similar purposes, for which small material is suited. If only selected trees are retained for saw timber they should be allowed to attain a large size in order to produce timber of high quality. Leaner : “# % hic hth he SPORE Ee nS ee oe epee bo PLATE II. dense sapling stand of shortleaf pine | profitably thinned. While the clean condition of the great damage in sucha stand. but too small to be floor is good, fire could do ’ 5 to 18 years old A SHORTLEAF PINE IN VIRGINIA ) CONDITION AND COMPOSITION OF OLD-FIELD STANDS As early as 1735 it had become a fixed part of the farming system of middle Virginia to clear new ground each year and to abandon to tallow a parcel of the oldest and most worn farming land. The land thus turned out was rapidly colonized with pines through seed blown by the wind from old trees nearby. When these pines had become large enough and the humus had been re- stored to the soil through them, the land was usually cleared again. Such a system of rotation of timber and cultivated crops was pos- sible only in a region where land was abundant and cheap. It was due in part to the lack of local markets, which made it necessary to export a large portion of the crops and therefore to produce them as cheaply as possible, regardless of the effect upon the soil; and in part to the fact that these soils were not natural grazing lands, and the depleted humus could be renewed naturally and cheaply by the replacement of the native pines. Some of the existing groves of old-teld pine thus originated before the Revolutionary War. Most of them, however, are younger, having originated dur- ing and just after the Civil War or in the subsequent periods of agricultural depression about 1880 and 1892. These stands are consequently of all ages; from the youngest, just in process of stocking land which has been turned out during the past decade, to those more than 100 years old. Stands between fifteen and forty-five years old are, however, the most numerous. Such old-field stands were thus established naturally, and no efforts were made by the owners to increase their density when they were too open or to protect them, while young, from fire. They have seldom been thinned judiciously for improvement. As a result, they vary widely in density. Small tracts are usually well-stocked, since, if seed-bearing trees were nearby while stocking ras taking place, seeds were in a few years scattered uniformly over the entire tract and such small tracts were often protected from fire by fences, or by adjacent cultivated fields. The trees in such well-stocked stands are slender and clean-bodied, with small crowns. The average tract, however, is poorly stocked. The trees are isolated, individually, or in irregular groups, and consequently short-bodied, knotty, and coarse-grained. This open condition of many of the stands is due to the fact that seed trees were too few or too distant while the stocking was in progress, or to the fact that the fields became grassy and the seedlings were killed by 10 SHORTLEAF PINE IN VIRGINIA fires that burned the grass. Scattered advance growth frequently has borne seed and so stocked the gaps. Such stands are irregular in age and size. Many of the older stands have been irregularly and often heav- ily cut for poles, cordwood, and even sawlogs. Most stands of sap- ling or larger size are too open for the best growth of the trees and for the highest financial returns. The proportion of shortleaf pine in the old-field stands varies. North of the Rappahannock river the proportion of scrub pine mixed with the shortleaf increases, until in Fairfax county and the lower end of Prince William county it largely replaces shortleaf pine. It is also largely mixed with shortleaf pine in stands near the mountains. In the shortleaf pine stands in the eastern ends of Hanover, Chesterfield and Brunswick counties, there is a large proportion of loblolly pine, which entirely supplants the shortleaf farther eastward. South and southwest of Hanover county the only pine in the field stands is the shortleaf, but species other than pine form part of the mixture in a varying proportion, though they seldom make up more than ten per cent. in stands younger than thirty-five vears old. In young stands these associated species vary with the kinds of seed-trees nearby. On lower slopes they are usually maple, poplar, sweet gum, and the oaks; on hilltops they are red cedar, oaks, hickory, black gum, persimmon, cherry, thorn, sassafras, and dogwood. PERMANENCY OF Otup-Fisnp Pine Stranps As the field pine stands become older, especially after they have passed the thirty-fifth year, their crown cover tends to thin, and this favors the growth of the oaks and hickories, which come in from seed dropped by squirrels, crows, jays, etc., and are better able to grow beneath the cover than are young pines. Even after the pine in the stand begins to seed the proportion of these broad- leaf species continues to increase, since the young pines can come in only when an extensive opening is made by the death of a large pine. There is thus a tendency toward a gradual re-establishment of the original forest tvpe which prevailed before the land was cleared, namely, a mixture of oak, hickory, black gum, and pine, with pine forming a small proportion on the best soil and a large proportion—frequently more than half the number of trees—on the poor, dry or sandy soils. The pure pine stands are, therefore, a temporary type, which in time will be replaced by the permanent mixed-growth type. SHORTLEAF PINE IN VIRGINIA WE It is not an invariable rule that “hardwoods follow pine” after cutting or that “pine follows hardwoods” after cutting or clearmg. But pure pine usually forms the second growth if there is no shade or cover, as in old fields or on hardwood land which has been cut clear in late summer or early autumn, when the sprouting power of the hardwoods is low. If seed-bearing trees are near, such open land, whether in field or forest, is captured in a few years by pine, by means of its abundant, light seeds which are widely scat- tered by the wind. The heavy seeds of oak, hickory and black gum, which are carried largely by birds and squirrels, are dis- seminated too slowly and irregularly to enable such species to compete successfully with pine in stocking nearby open lands. Un- der these conditions, pine usually follows oak. On the other hand, pine is unable to establish itself beneath dense shade, whether of pine or of hardwoods. For this reason young pine growth is seldom found under the trees except in older open pine stands. ‘The seeds of hardwoods, however, are dropped from year to year in such stands and germinate; and the seedlings, through their persistency and ability to endure shade, will survive in shade in which a young pine can not live, although their growth in this case is extremely slow. When the large pines are cut, these stunted hardwoods, responding to improved conditions of ight and root space, grow rapidly and if they are numerous they form the larger part of the growth which follows the pine. In those portions of the State in which it occurs, scrub pine affects the permanence of the shortleaf pine stand on medium soils even more than do the hardwoods. Scrub pine seeds prolifically, when much younger and smaller than shortleaf pine, and the seed- lings are tolerant of far more shade than those of the shortleaf. For these reasons, it not only excludes the shortleaf from old * fields which are in process of stocking, but it successfully competes with the young hardwoods in occupying openings in stands of shortleaf pine in which the cover is too heavy for shortleaf seed- lings to exist, and thus in part succeeds the shortleaf in shortleaf stands. By reason of this aggressiveness, scrub pine is so completely replacing shortleaf pine over large areas in the northeastern part of the State and near the Blue Ridge that the economic range of shortleaf pine is being restricted. 12 SHORTLEAF PINE IN VIRGINIA MANAGEMENT Forest management as applied to old-field stands may be sum- marized as the use of any methods of restocking, cutting, or thin- ning which will reduce the cost of growing timber or add to the value of the timber grown. Natural stands are usually either understocked, at least in certain phases or during certain periods of growth, or else over- crowded, The maximum growth is obtained by maintaining such a num- ber of trees to the acre as will utilize the full capacity of the soil and at the same time secure the best development of the individual trees. Understocked stands do not use the full capacity of the soil and must be filled out to the required density by planting in the thin places. In crowded stands, on the other hand, the indi- vidual trees are retarded; they must be thinned in order to make them grow at their best rate. These requirements of the stand are discussed in connection with the subjects of thinnings and planting. Another phase of management is cutting at the period of ma- turity as determined by either maximum yield or value. The rate of growth or accretion of a stand is not the same at all ages. The yearly growth rapidly increases from nearly nothing to a maxi- mum, then slowly declines. When the rate of annual growth be- gins to decline, a loss in yield is entailed if cutting is deferred. The time at which the maximum of the average annual yield is obtained varies with the size of the timber which is desired; it would not be the same for lumber, which requires large timber, as for cordwood, for which small timber can be used. But while it is desirable to obtain the maximum annual yield from a stand, the cost of production is a factor which cannot be neglected. The cost of production embraces the interest on the investment, the taxes, superintendence, protection, and the making of improve- ment cuttings and thinnings. As far as the needs of owners and the market conditions allow, a stand should be cut at financial maturity, that is, when it yields the best returns on the investment. ‘These phases of management are considered in connection with vields of stands at different ages, and with the cost of growing timber. One of the most important considerations in manage- ment is the method employed for obtaining a prompt renewal of the stand in order to prevent the loss of interest on the investment by the idleness of the land. SHORTLEAF PINE IN VIRGINIA 13 Protection of stands from fire, from insects, and from fungus diseases is necessary to insure fully stocked stands and sound timber. ‘The figures relating to the growth and yield of shortleaf pine are based on stands which are growing on soil formerly covered with forests of shortleaf pine mixed with white oak, southern red oak (Quercus digitata), black oak, and white hickory. The rate of growth on such sites is regarded as the average or usual rate. Where the pine now grows on soils which were formerly covered with forests of shortleaf pine mixed with post oak, with black-jack oak, or with Spanish oak (Quercus coccinea), or with a large propor- tion of these oaks together with other oaks, the rate of growth and the yield of the stands will be considerably lower than that given. Fuity Srockep AND Crowpep, STANDS A stand is fully stocked when it contains all the well-grown, vigorous trees which the soil can support. This number decreases with the age of the stand and the consequent increase in the size of the trees. In a natural twenty-year-old stand of shortleaf pine the number to the acre should exceed 1,500; at forty years it has decreased to about 75U; at sixty years it has fallen to less than 450. This reduction of the number of trees in a stand progresses nat- urally. As the trees become older and larger, their crowns spread and their roots extend in search of food and moisture. Competi- tion for light, food and moisture ensues, and this in turn results in the dying of the smaller and weaker trees, which are overtopped and crowded out by the more vigorous ones. A fully-stocked stand, in which natural thinning is taking place rapidly, is crowded (plates I, IJ and IV). At any age the fact that a stand is crowded is indicated by a close crown cover and the presence of many dead trees and slender live trees with narrow crowns. In a young stand of this character less than thirty-five years old the crowding 1s so great that the crown of each tree al- most touches the crowns of its neighbors and direct sunlight hardly reaches the soil. The shade is sufficient to prevent the start of young trees and most shrubs beneath the pines and the carpet of pine needles is so thick as to exclude grass, while small dead trees are numerous. In stands more than thirty-five or forty years old there is a wider distance between adjacent crowns, due to the rapid dying of the larger of the slender narrow-crowned trees. This opening of the stand admits more sunlight, and young oaks, hick- 14 SHORTLEAF PINE IN VIRGINIA ories, and other trees, as well as many shrubs, begin to grow be- neath the pines. Dead trees and live trees with narrow crowns are . not so numerous as in younger stands. The mat of pine needles is thinner in the older stands and grass is able to spring up. A fully-stecked young stand of shortleaf pine has, therefore, a dense crown cover. In both young and old stands, if they are fully stocked, there are slender trees with narrow, spry crowns and dead trees which have been crowded out, though the latter are more abundant in the young stands. Whether a stand is crowded and in need of thinning may be determined by the greater or less abund- ance of crowded and dead trees, considered in connection with the age of the stand and the normal density of the crown canopy at a given age. UNDERSTOCKED STANDS ‘The average stand of shortleaf pine in middle and Piedmont Virginia, however, instead of being too densely stocked, is too thinly stocked. When the crowns do not interfere, or are round- topped with practically horizontal lower branches, the stand is too open for best growth. Young and even middle-aged stands are frequently open, but their wide-spreading crowns eventually close and form a dense crown cover like that of a fully-stocked stand. But in this case dead trees and slender overtopped trees are absent; the crowns of the trees are too round and wide-spreading; the stems are too short and limby; and the number of trees to the acre is much less than in fully-stocked stands of the same height. (Table 9). Under- stocked stands of this kind do not require thinning. Moderately understocked young stands usually become crowded early enough to reduce some of the evils of understocking, but the stems of the trees are never so tall and free from limbs and knots as those which develop when there is crowding all through the life of the stand and their total yield is usually less than that of a fully- stocked stand. (Plate III). Young understocked stands should be filled out by planting. In nearly every stand, however, there will be found at least groups of trees which will be benefited by thinning. The presence in the stand of numerous small dead trees and slender trees with spiry crowns is a clear indication that thinning is needed. SHORTLEAF PINE IN VIRGINIA 15 THINNINGS The objects of thinnings are, first, to accelerate the growth and shorten the time necessary to bring the stand to maturity, and, second, by removing defective trees fo produce a mature stand formed of perfect specimens and so increase the vield of lumber. The elimination of the weaker specimens by natural process takes place too slowly for the best development, because the growth of the trees which are ultimately to survive is retarded by the pro- Jongation of the struggle for light and food. Yet limited crowd- ing is necessary at certain periods to force height growth and to develop long, straight stems, reasonably free from limbs. More- over, the number of trees to the acre largely determines the volume of the yield and has an important bearing on the value of the trees. Usuilly the crowded stands produce the greatest volume of wood at all ages; but when the size or diameter of the individual trees is of primary importance, as in the production of saw logs, less crowding is desirable. By means of judicious periodic thin- nings, it is possible both to favor competition and to relieve over- crowding and in this way greatly to accelerate the growth of the remaining trees. Such thinnings reduce the number of trees, but they produce equally tall trees of much larger diameter, with straight, clean stems and but little taper. It is commonly held that if the larger trees are removed as they come to merchantable size the smaller trees will make accelerated growth. This is un- questionably true of many species and it is true also of short- leaf pine under thirty years old, but in pure old stands of short- leaf pine in Virginia the crowded and suppressed trees recuperate so slowly that it is not profitabie to thin the stands in this way after they have passed the age of thirty-five. years. CLASSES OF TREES Before thinnings can be intelligently made, the classes of trees in a stand must be known and their relation to the growth of the stand understood. The live trees in a second-growth pine stand can be separated easily into three classes: Dominant Trees—These are the tallest and thriftiest speci- mens with the largest crowns. Their growth is rapid, both in height and in diameter. Intermediate Trees—These are the slender, clean-bodied trees, with narrow, compressed erowns which are nearly as tall as the 16 SHORTLEAF PINE IN VIRGINIA dominant trees. Their height growth is rapid, but, on account of their small crowns, their diameter growth is slow. Besides be- ing unable to make good volume growth themselves, they retard the growth of the dominant trees. Suppressed Trees.—These have fallen behind in height and are so much lower than the other trees that direct sunhght is largely excluded from them. They interfere very little with the growth of the larger trees. When overshadowing and suppression pass a certain point the trees die. Three-fourths of the dead trees are in the sup- pressed class, but intermediate trees also die trom overcrowding. Dead trees exert no influence upon the growth of the stand. When possible, however, they should be removed, since they contribute to the danger of disease, insects, and fire. HOW HEAVILY TO THIN Thinnings must be heavy enough to provide more hght and crown space, and more root space and soil moisture for the trees that are left, yet they must never be heavy enough at one time to admit too much sunlight and cause the crowns to spread unduly, with a sacrifice in the rate of height growth. Too heavy a thin- ning results in temporary understocking and produces the oppo- site of the result desired. To be most effective, thinnings should begin when a stand is twenty years old, and should be hght and frequent. Early thin- nings prevent the crowns from crowding before their, symmetry is destroyed, and yet maintain sufficient crown rivalry to secure continuous height growth and promote the rapid shedding of the lower limbs. Before removing any tree, it 1s necessary to con- sider how its removal will affect the remaining trees, not only un- til the next thinning, but until the stand is mature and the trees are merchantable. Thinnings should be made not less often than once every ten years. Even with ten-year intervals cuttings have to be too heavy for the best interest of the stand and excessive crowding takes place before a thinning is repeated. An interval of five years is recommended as the most desirable. This develops the full value of the stand, and also allows the cutting of enough cordwood from the thinnings to pay for the work. A careful observer will be able to lengthen the interval if the cost of thin- nings requires it. q% Tee tis ies : sl St eee mt PLATE III. -ge pole stand of ied and knotty and w The trees are The best that can shortleaf pine 80 years old ield only low grade lumber Understocked |ai illy bod be done with such a stand is to cut it, leaving slender, clean-bodied trees for seed trees. short SHORTLEAF PINE IN VIRGINIA M7, WHAT TO REMOVE IN THINNING Thinnings should remove such suppressed trees as are not necessary to complete the crown cover, since they have made their growth and exert little or no influence on the growth of the large trees. Species of lower value, like gums, post oak, maple, sassa- fras, and scrub pine, should also be cut, unless they are needed to keep the crown cover complete. Punky or diseased trees should be removed from stands of all ages. Short-bodied, crooked, knotty, forked, or otherwise defective pine trees should be cut from younger stands, but should be left in old stands when their removal would make openings which would not be filled by the spread of the surrounding crowns. Enough of the intermediate class should be removed to provide growing space for the trees that are left. The trees which are removed should be selected evenly through the stand. If several adjoining trees are removed, an opening is left which will be too long in closing. If trees are left in groups, excessive crowding in the interior of the groups will follow, and this will result in the loss by shading of the in- terior branches and unsymmetrical development of the trees. When there is a choice the trees which are left for permanent growth should have well-developed and symmetrical crowns. ACCELERATION IN GROWTH FROM THINNING Until they are thirty or even thirty-five years old, the inter- mediate as well as the dominant trees of shortleaf pine stands re- spond vigorously and rapidly to thinnings by accelerated growth. In colder stands, the recuperative power of the intermediate trees declines and the recovery from the effects of overcrowding is slow. The recuperative power of the dominant class, however, is main- tained until the trees are sixty years old, when the period of rapid height growth is well past and crown isolation has taken place. The ability of the intermediate trees in young stands to recover rapidly from the effects of close crowding, permits the cutting of the largest trees in such stands and the leaving of the slender, clear-stemmed intermediate trees to form the mature stand. In Plate VI, fig. 1, which shows the cross section of a stem of shortleaf pine, is to be seen the results of accelerated and sus- tained growth which are due to repeated light thinnings. The crowded condition of the inner rings of growth show that the tree was a slender, intermediate tree before its crown was freed by the 18 SHORTLEAF PINE IN VIRGINIA original thinning, made, as shown by the number of wide rings, forty-seven years before the tree was cut. Several thinnings, made since the original thinning, have prevented any marked decline in the comparatively rapid rate of growth which took place after the crown of the tree was originally freed of overcrowding. The rate of growth is one inch of radius every eleven years, or about one inch in diameter every five years ‘(the bark thickening as well as the wood),—an excellent average rate of growth to seek to main- tain in the trees of a stand. It produces timber suitable for the highest classes of uses. METHOD OF THINNING The several thinnings are for the benefit of the final cutting and unless the thinnings are made at a profit, the yield of the final cutting must be far heavier as a result of the thinnings in order to make them worth while. In young stands then, it 1s possible to distribute a portion of the thinnings in the dominant class; in old stands, thinnings must be largely restricted to the suppressed and intermediate classes. Stands more than twenty years old, which have never been thinned, require heavier thin- nings than stands of the same age which have been thinned pre- viously. ; Sapling Stands (Younger than Tweny Years). —Thinnings ot sapling stands are seldom possible on account of the expense of making them and the small amount and poor character of the wood obtained. Under average conditions of growth, the wood which could be cut in a thinning in such a young stand would be from two to four inches in diameter and would make only a poor quality of fuel. Thinnings at this age are not recommended unless the wood can be used. (Plate IT). Small Pole Stands (From Twenty to Thirty Years Old) —A crowded stand twenty-five years old contains a number of large trees eight or nine inches in diameter breasthigh, and a few even ten inches; many of which are in the advance growth, two or more years older than the average age of the stand. Such trees are fre- quently bushy and very limby, with wide-spreading crowns. Usu- ally all of the nine and ten-inch trees in such a stand and many of the eight-inch trees can be cut. These will furnish a small quan- tity of saw timber. In addition to the large trees, all of the trees below four inches, and usually about one-half of the five-inch trees can bé removed. If no previous thinning has been made, about SHORTLEAF PINE IN VIRGINIA 19 200 trees five inches and larger could be cut to the acre. These should yield about ten cords of wood, of which the material above nine inches might be sawed into about 500 board feet of lumber. About 900 trees should be left to the acre. A thinning in a twenty- year-old stand should yield much less, and one in a stand more than twenty-five years old should yield more and leave fewer trees per acre. At these ages trees are making very rapid growth, and the branches of the crowns are sharpiy ascending, so that com- paratively large openings are more quickly covered than in older stands. For this reason thinnings at this period present no seri- our difficulties, but it is desirable even in making a thinning at this age to have in view the trees which are to form the final stand and these should be the tree with very slender and clean stems, that will yield several logs, and from which lumber can be sawed free or nearly free from any except small knots. For the relative value of these trees compared “vith the larger dominant trees in a stand, see table 16. (Plate I). Large Pole Stands (From Thirty to Forty Years Old) —A\ trees below six inches, most of the six-inch trees, and some of the seven and eight-inch trees, should be removed from a normal thirty-five-year-old stand. If no previous thinning has been made, not less than 200 trees could be cut, many of which would, how- ever, be five inches or less in diameter. If a thinning has previ- ously been made, there would be fewer trees to come out. UNTHINNED STAND A 5 5 ee @roua vate Gross rate stand per cent. Yield ieler Gere Yield per ES stand Vieidedvon per VERS paced Acre neglectin - of mininniniee ee ate cee stand Value Years| Bi. ft. Per cent. Bd. ft. Per cent. | | | | 30 8,400 | - $16.80 | 4,3 rep lus 35 13,400 26.80 50 Pe caer 40 16,400 | 32.80 50 6,000 | $12.00 2.5 45 18,700 37.40 4.5 10,200 | 20.40 3.2 50 20,400 40.80 4.0 || 13,100 | 26.20 3.3 TABLE 14. CORDWOOD STUMPAGE OF FINAL YIELD AT 24 CENTS A CORD. 4 Gross rate per cent yielded by stands of shortleaf pine in old-field with a land value of $5 an acre.* THINNED STAND —UNTHINNED STAND Age i ie Arenas ee ee ait Total Value, per eee Yiela | Gross rate cand Final F eee per cent, ae | yer Cent. vas yield aoe eS Yielded on per | value Yielded on i umu t; A To of Thinnings at 4¢ Land Value cre stand Land Value Years Cords com pound interest Per cent. Cords | Per cent. 20 “it” SII kes Me gen raed | Seas ae 49 | $11:75 43 25 52 $13.74 4.0 57 14 25 4,2 30 57 16.08 4.0 62 15.50 3.8 35 60 | 18.44 3.8 64 16.00 3.5 40) 60 | 19.65 | 3.6 65. | 216525 3.0 45 59 23.94 3.5 | 64 16.00 28 50 57 26.43 ae 63 15.75 2.5 * Gross rate per cent. includes taxes and cost of protection as well as the interest on the investment. yA SHORTLEAF PINE IN VIRGINIA VALUE OF TREES AND STANDS The lumber from second-growth stands of shortleaf pine, when .awed into boards one inch thick and graded according to the rules of the North Carolina Pine Association, sells for a high- er price than if it is sold ungraded, or than if it is sold in the form of framing. The lumber which is sawed from young stands less than 35 years old is as a rule too narrow, and that from stands in which the trees have not been crowded, is too knotty to justify grading. The older the stand the more valuable becomes the lum- ber which can be cut from it not only on account of greater widths but also a larger proportion of the high grade.. If the trees of different diameters in a crowded stand which is about 50 years old (the age of maturity) are carefully sawed into boards of even width and uniform thickness, they will yield approximately the amounts of the different grades of lumber which are given in Table 15. The figures in this table are based on actual measure- ments of grades which were made at a mill where trees of these sizes and age were being cut. TABLE 15. Total volumes in board feet, and the amount of the grades of lumber in trees of different diameters and heights in dense stands of short-leaf pine 45 lo 60 years old. | AMOUNTS OF THE DIFFERENT Diameter rota) | wumner |faungte”|__ GRADES Sawen From Trees | Zola high helene nae | rates | No.1.) No. 2. | No. 3. |Box or| Other we ed Inches | | niches Biche ae Se Bd. ft. | 7 | 48 1} 5.0 ry eae) 6 22 8 53 14 6.0 2 6 14 Ges 28 Orne spree 6.5 4 133) 45 6 38 10 62 2h 6.5 4 8 igs) 4g 6 55 11 66-year ae 6.5 8 12). |. 25-5) 298 6 79 12 Wiig eens 7.0 18 | 93 | -87,.|_ 35 6 109 1B 4) 75. 3° A). 7:0 S286 2 Saas 6 142 14 78 See shee Wed 82 | 38 | 48 | 56 7 J81 15) =) 2} "280 34 7.5 AT | 06 1 eae eae 9 226 Wie ol bets a eee 8.0 70. | 4Ge.| > 7bo) rere attee 280 de SO 3h 8.0-- | 74-| 6051 108) Bre ae 338 18 81 3} 8.0 B36 l= 76.1 180") LOB" feette 398 19 81 3} 8.5 92-1 2) “dss Tasers ete 460 20 81 33 90 105; (115 fe67- 1.492 3 aie 527 21 81 34 9.0 120. |.188 {197 195°") 48 598 22 81 33 9.0 136 | 163 | 230 | 129 | 20 678 The smaller trees in stands of this age are long-bodied and clear stemmed, have very little taper and thin bark, and, although a Vic Trees nearly uniform in size and ready to windfirm trees ¢ x u PLAT and of shortleaf pine. Mature st be cut for lumber. an be left for seed trees. ’ Groups of slender a J pao tse Dy) 0 Nhe SHORTLEAF PINE IN VIRGINIA 318 the boards which can be sawed from such trees are narrow, they are comparatively free from knots and will justify grading if handled in connection with the wider boards from the larger trees. Trees of the same size in younger stands are more tapering and more knotty, and the lumber is of lower grade. Air-dried lumber of the different grades, consisting of mix- ed width, but less than 12 inches wide, is quoted (November, 1912) at the following prices per 1,000 board feet, delivered at Norfolk, * Richmond, Petersburg, Lynchburg, and Roanoke: No. 1, $26; No. 2, $24; No. 3; $20; Box, $18; Red heart and cull, $16; Bark strip, Nos. 1 & 2, $20; Bark strip, box $12. In Table 16 these values have been applied to the amount of different diameters delivered at Norfolk and the other points named above. TABLE 16. Value delivered at Norfolk, Richmond, Petersburg Roanoke, and Lynchburg, of the graded lumber cut from trees of different diameters and heights* growing in crowded second-growth stands 45 to 60 years old and the value of single trees and their stump- age per 1,000 board feet under different costs of sawing and delivery at these points. Value of lumber de- | Stumpage value per tree with ex penses livered at Norfolk, Rich- | of sawing and delivery per Diameter mond, ete. | 1,000 board ft. at breast-high SesrS cde - | - Frome | hoards |e a4 7 § .36 $15 95 Selon | $ .08 - $ .40 8 47% 16.40 .18 | 12 .06 i) .66 17.40 | 28 78H PA 13 10 1.01 18.35 | 46 | 85 24 11 1 53 19.80 74 .08 42 2 2.16 19.80 1.06 .85 638 13 2.86 20aee 1.44 | 1.16 .87 14 Bite 20.95 1.98 | 1.62 1.26 15 4.75 21.40 2.58 Pas 1.67 16 6.80 22.50 3.58 8.02 2.46 17 7.60 22.05 4.23 38.56 2.89 18 8.95 22 50 479 | 4.18 3.38 19 10.40 22.45 5.73 4.81 3,89 20 11.80 . 22.40 6.53 | 5 48 4.42 , 21 13.40 22.40 7.41 | 6.22 5.02 22 15.17 22.39 8.37 | 6.01 5.65 \ *Heights which are given in table 15. +Obtained by deducting thecost ofsawing and delivery per 1,000 board feet from the de- livered value per 1,000 board feet, reducing the remaindér to the value of one board foot and multiplying by the number of board feet per treeas shown in table 15; thus, $15.95 less $10.00 equal to $5.95—$5.95 divided by 100 and multiplied by 22 is equal to $.13. In table 15 the expenses of sawing and delivery, $10; $12; and $14 per 1,000 board feet are supposed to represent a low, 34 SHORTLEAF PINE IN VIRGINIA a medium, and a high cost of operation, and are made up of the cost of logging, felling, sawing, grading, interest on the investment and carrying charges, cost of selling, delivery at market and load- ing, drying, and profit of the operator. A profit of from $2 to $3 a thousand feet should be allowed in portable mill operations, the. profit varying according to the size and length of the oper- ation. It is noteworthy that while the value of the lumber per 1,000 board feet which is yielded by trees of different diameters increases rapidly up to 16 inches in diameter, there is a decline in the value per 1,000 feet of the lumber which is sawed from trees of diameter above 17 inches. This is due to the fact that the largest trees in these stands have larger and more numerous knots in their stems and yield a lower proportion of the high grades of lumber than do the slender, more clean stemmed, intermediate, and suppressed trees. If the number of trees of each diameter per acre in a 45- year old stand (see Table 2) be multiplied by the value per tree of each respective diameter, the sum of these amounts will give the total value of the stand per acre, and from this the value per 1,000 feet of the stand. A similar set of values can be determined for trees in younger and older stands. These are given in Table 17. TABLE 17. Value per 1,000 board fect of the lumber which can be sawed from dense unthinned stands of short-leaf pine under different costs of manufaeture and delivery. | Value per 1,000 board feet under a cost | of operation and delivery of years $10 | $12 | $14 pias Kaweasce ek 3 | $ 5.40 | $ 3.40 | $ 140 40 | 6.00 | 4.00 2.00 50 7.05 | 5.05 3.05 60 | 8.60 | 6.60 4.40 70 | 10.05 | 8 05 6,05 If the values in Table 17 are compared with the cost per 1,000 board feet of growing timber, shown in Table 10, it will be seen that the investment, if the stand is unthinned, dees not yield five per cent. net, except under a logging cost of $10 and when the stand is cut at the age of 50 years. In a régularly thinned stand from which the very knotty trees have been systematically removed when the stand was young, SHORTLEAF PINE IN VIRGINIA aD Jeaving only the longest-bodied and clearest stemmed trees at each cutting and in which the trees have been forced to large diameters by isolation after the clear stem-length is 50 feet in length, it is believed that the stumpage value can be forced to a ralue of $8 a 1,000 feet under a logging cost of $12 when 50 years old. This would yield about $250 per acre. WASTE IN CUTTING SMALL TREES The following table shows the actual volume in board feet of trees of ciiferent diameters and heights when cut with a saw taking a kerf of one-fourth inch; the volume in board feet when scaled by Doyle-Scribner log rule; the volume of stem, wood only, in cubic feet; the number of board feet, Doyle-Scribner rule, per cubie foot of volume; and the percentage of waste. TABLE 18.. Volume in board feet and in cubic feet and per cent of waste in sawing trees of shortleaf pine of different diameters. | Volume miezae- Fe | Actual 28 aie Seles ee Bbe cant Beant | Height | 14 crm Berinner: Wood Actual number | of waste in high | | Saw Kerf rule only of Board feet, | Stamp, | | per Cubic foot | Tops, Slabs | : Cubic | and Kerf Inches | Feet | Board feet Board feet feet | | Tank DON 7) e422 8 7 3 75 8 55 28 | 16 10 3 75 9 GOR