Me U. S. DEPARTMENT OE AGRICULTURE. BUREAU OF PLANT INDUSTRY— BULLETIN NO. 57. B. T. GALLOWAY, Chiif of Bureau. METHODS USED CONTROLLING AND RECLAIMING SAND DLNES. A. S. HITCHCOCK, Assistant AGKOSTOLOtiiST, in Chakgk of Cooperative EXPEKIMENTS. C ^ASR AND FORAC-.E PLANT INVF.RTIGATIONS. Issi KJ) ]\r.\i;<.ii 10, U)04. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1004. Hdrwgrapb Glass ^ ^% Book. W^— 7^ /3r 2-^ jl. 57, Bureau of Plant Industry, U. S. Dept, of Agriculture. Plate I. Beach Grass (Ammophila arenaria Link). U. S. DEPARTMENT OF AGRICULTURE. BUREAU OF PLANT INDUSTRY— BULLETIN NO. 57. B. T. GALLOWAY, Chief of Bureau. METHODS USED CONTROLLING AND RECLAIMING SAND DUNES. A. S. HITCHCOCK, Assistant Agrostologist, in Charge of Cooperative Experiments. GRASS AND FORAGE PLANT INVESTIGATIONS. Issued Makcii 10, 1904. WASHINGTON: • ' : government printing office. 19 04. &4 BUREAU OF PLANT INDUSTRY. Beverly T. Galloway, Cliii'f of Bureau. GRASS AND FORAGE PLANT INVESTIGATIONS. Scientific Staff. W. J. Spillman, Agroslologlst. A. S. Hitchcock, Assistant Agroslologlst, in Charge of Cooperative Experiments. C. V. Piper, Systematic Agrostologist, in CJiarge of Herbarium. C. R. Ball, Assistant Agrostologist, in Charge of Work on Arlington Fitrm. David Griffiths, Assistant Agrostologist, in Charge of Range Investigations. JAN 8 1907 D.ofO. LETTER OF TRANSMITTAL U. S. Department of Agriculture, Bureau of Plant Industry, Office of the Chief, Washington ^ D. C.^ January 7, 190 J^. Sir: I have the honor to transmit herewith a paper on "Methods Used for Controlling and Reclaiming- Sand Dunes," and respectfulh^ recommend that it be published as Bulletin No. 57 of the series of this Bureau. This paper was prepared by Mr. A. S. Hitchcock, Assistant AgTOS- tologist, in Charge of Cooperative Experiments, Grass and Forage Plant Investigations, and has been submitted b}- the Agrostologist with a view to publication. Respectfullj', B. T. Galloway, Ch ief of Bureau. Hon. James Wilson, Secretary of Agriculture. PREFACE On the Atlantic and Pacific coasts,. on the shores of the Great Lakes, and at numerous places inland, there are areas of sandy land, for the most part originally covered by vegetation, but now denuded of plant growth through the shortsighted policy which has so often prevailed in this country of utilizing everything in sight without reference to the future. The Department of Agriculture is frequently called upon for advice concerning the proper methods of controlling this sand and pre- venting it from drifting. In some cases cultivated fields have been invaded and railroad tracks covered. The sand has even invaded cities, covering up houses and filling the streets, and much valuable property has thus been destroyed. Much work has been done in controlling shifting sand dunes in Europe during the past century, and methods have been developed whereby it is possible to control the sand and in many cases to cover it again with vegetation. On account of the importance of the subject. Prof, A. S. Hitchcock, of this oflice, was sent to Europe recently to stud}^ the methods there used in this work. In the autumn of 1902 he visited the Netherlands, Denmark, German}', and France for this pur- pose. An outline of the methods that have been successfully employed in those countries is given in this bulletin, together with some other information of general interest concerning the subject of sand dunes. f • W. J. Spillman, Ag7'ostoloffis(. Office of the Ageostologist, Washington, D. C, Deceiiiber 16, 1903. 5 CONTENTS Page. Introduction 9 Formation of sand dunes 9 Action of the wind upon drifting sand 11 Artificial fixation of dunes 13 Binding the sand 14 Binding by means of grasses 14 Transplanting 14 Arrangement of the plantation 16 Formation of the barrier dune 17 Binding by means of heather 19 Laying the heather 19 Binding with sand hedges 20 Forestation 21 Fixation as oljserved in Europe 22 The Netherlands 22 Coastal dunes 22 Interior dunes 23 Denmark 25 Oxbol 25 Skagen 26 Germany 27 France 29 Summary 32 Description of plates 35 7 ILLUSTRATIONS. PLATES. Page. Pl.\te I. Beach grass Frontispiece. II. Fig. 1. — Dunes held b}- covering of heather. Fig. 2.— Making a road in the dunes 36 III. Fig. 1. — Pine plantation in covering of heather. Fig. 2. — Heather among the dunes 36 IV. Fig. 1.— Beach grass plantation along base of dunes. Fig. 2. — Beach grass and sand fence on barrier dune 36 V. Fig. 1. — Lee slope of barrier dune. Fig. 2. — Remains of once buried forest 36 VI. Fig. 1. — General view of barrier dune. Fig. 2. — Unreclaimed shift- ing dune 36 VII. Fig. 1. — Digging beach grass for planting. Fig. 2. — Transplanting beach grass 36 VIII. Fig. 1. — Sand fences protecting base of dune. Fig. 2. — Protecting a road through the dunes 36 IX. Fig. 1. — Shifting dunes held by brush fences. Fig. 2. — Shifting dunes held by reed fences 36 TEXT FIGURES. Fig. 1. Drifting sand as affected by a solid fence 12 2. Drifting sand as affected by an open, inflexible obstruction 12 3. Drifting sand as affected by an open, flexible obstruction ^ 12 4. Spade used for planting beach grass 15 5. Method used in planting beach grass 16 6. Diagram showing the successive steps taken in forming a barrier dune. 17 7. Repairing a small breach in a barrier dune by planting grass 18 8. Repairing a larger breach by means of sand fences 18 9. Spade used in Prussia for transplanting young trees 21 B. P. I.— 92. G. F. P. I.— 102. METHODS USED FOR CONTROLLING AND RECLAIM- ING SAND DUNES. INTRODUCTION. The sand-dune areas of Europe are of especial interest because they present conditions similar to those found in the United States and because it is there that the methods of reclamation were first applied and later most successfully developed. In order to investigate the methods used and determine to what extent they might be applied in this country, the writer visited several regions in Europe where the conditions and methods may be considered representative — the Netherlands, Denmark, the southwest coast of France, and the Kurische Nehrung on the northeast coast of Germany, In Prussia much work has been done along the coasts of the Baltic and North seas, but this is so well described in Gerhardfs ■' admirable book upon the dunes of Germany that other points than the ones mentioned were not visited. There are other localities of minor importance where dunes occur and where efl'orts toward reclamation liave been made, but it was not learned that the methods used differed essentially from those investi- gated. Lack of time prevented visits to certain other interesting interior regions, such as the Banat plain of southern Hungarj^, the north shore of the Black Sea, and Russian Turkestan. The last two regions are of importance because of the efforts put forth by the rail- roads to prevent the enroachment upon their right of waj^ by shifting dunes. FORMATION OF SAND DUNES. Sand hills or dunes usually occur along a sandy seacoast. The sand is constantlj^ washed up by the waves and when dry is readily carried inland by the wind. On a rocky or marshy coast this does not occur. « Paul Gerhardt, Handbuch des deutschen Diinenbaues, Berlin, 1900. This is a very- complete and detailed account of the sand dunes of Germany, including geology, flora, formation, reclamation, and historical notes, and is the most elaborate work of this nature thus far published. The writer is indebted to this work for the text figures used in this bulletin. Mr. Gerhardt was superintendent of the Konigsberg district (Regierungs und Baurat) and was later advanced to the charge of the entire work at Berlin. 9 10 METHODS USED FOR CONTROLLING SAND DUNES. Under the action of the wind the sand accumulates in ridges or hills of irregular contour and extent, depending upon the force and direction of the prevailing winds. It is not intended here to go into the details of dune formation, a subject which has been elaborated in Gerhardt's book and also in numerous lesser works. Suffice it to say that ordi- narily a dune passes through a rather definite series of changes. It is formed near the beach and travels back toward the interior. A typ- ical wandering dune presents a gradual slope toward the wind and an abrupt slope on the lee side. The wind forces the sand up the slope and it falls over the edge. The hill or ridge then travels in the direc- tion of the prevailing wind at a rate depending on the force and con- stancy of the latter. Such a hill is called a wandering dune. As the dune recedes from the coast a new one may form at the beach. Upon the wandering or active dunes the sand is shifting to such an extent that vegetation does not establish itself. Consequently such dunes are bare. During wet periods seeds may germinate, but sooner or later the flying sand destro3^s the plants either by cutting them off as by a sand blast or by burjdng or uncovering them. However, as the action of the wind becomes less forcible at a distance from the strand, vegetation is at last able to become established and resist the enfeebled sand blast. A wandering dune is thus gradually converted into a lixed dune, which, if left to itself, finally becomes forested. Similar dunes are often formed along the larger rivers or on interior sandy wastes such as are found in the central portions of the Nether- lands and Denmark. It not infrequently happens that a fixed dune becomes converted into a wandering dune. This occurs through the removal of the vegetation, either by natural means or as the result of man's carelessness. The result in the first case is usually brought about by changed conditions, such as the direction of the wind, whereby the vegetation dies in certain spots and " blowouts " are formed. Such cavities or blowouts gradually enlarge as the surrounding vegetation is undermined and the result may be the birth of a wandering dune. But from an economic standpoint by far the greatest harm has come from the removal of forests from fixed dunes. The Kurische Nehrung in Prussia and the coast dunes of the Netherlands were at one time covered with forest and gave no trouble. Other cases are known where dunes held permanently b}^ a covering of grass have been con- verted into wandering dunes by the pasturing of cattle upon them, thus cutting up the sod. Sand dune* of any considerable extent are rarely found along the seacoast in warmer regions, because the long growing season is more favorable to vegetation. The forest, or at least a scrubby growth of shrubs, usually comes down close to the high-water mark. The severe winter storms of the high latitudes are chiefly responsible for the great dune areas of the north. FOEMATION OF DUNES. 11 In many cases the wandering dunes encroach upon arable land, upon forest, upon valuable property such as railroads and buildings, or upon rivers, harbors, or other water waj's. This usually indicates that there has been a recent change of conditions resulting in the formation of active dunes. Seaside resorts upon sand}^ beaches are often seriously damaged by the formation of dunes and blowouts upon various portions of the property. In addition to the trouble arising from the encroachment of sand at points Avhere it does damage, it should be understood that there are large areas of sandy land consisting of dunes in various stages of fixa- tion, interspersed with portions of level and sometimes arable land. These level spots represent portions where the wind has swept away the sand down to moist soil, which usually has a definite relation to the water level. Such areas of dunes may include many square miles and are useless for agricultural purposes. It is thus seen that the fixation of dunes may be for two purposes — to protect propert}^ in the lee or to convert a useless area of waste land into a productive forest. ACTION OF THE WIND UPON DRIFTING SAND. When the wind sweeps over a free surface of drifting sand it acts about equall}^ throughout; but an obstruction of an}^ kind, such as a log or a bunch of grass, at once modifies the action of the wind. A solid object increases the force of the wind around the sides, and hence the sand is excavated. In the lee of the object the sand will accunuilate. If two such obstructions are near together a channel is formed between them and once formed deepens with astonishing rapidity. The carrying power of the wind increases much more rapidly than the increase in the velocity." Consequent^, any increase in the velocity is immediately noticeable in the increased erosive power. The erosive power of the wind is not identical with the carrying power, for in the first case the wind overcomes cohesion and in the second case it overcomes weight. If the velocity of the wind decreases, the sand previously held in suspension is deposited. If a solid fence is placed upon the sand at right angles to the wind « Theoretically the transporting power of the wind varies as the sixth power of the velocity — that is, if the velocity is doubled the carrying power is 64 times as great. It is clear that the force exerted by the wind upon a fixed surface increases as the square of the velocity, for if the velocity of the wind is doubled there will be twice as much air striking the surface with twice the velocity. Furthermore, if the velocity remains the same the force exerted increases with the surface — that is, with the square of the diameter. The moving power then varies as the product of the square of the velocity and the square of the diameter. But the force or work done, which is the same as the weight of the object transported, varies with the cube of the diameter; or, putting it all in terms of velocity, the force varies as the sixth power of the velocity. 12 METHODS USED FOR CONTROLLING SAND DUNES. the sand is excavated in front (tig. 1). The wind, unable to proceed, is divided into currents in all directions. Those going downward scoop out the sand, thus forming a drift a short distance in front. This increases until its height equals that of the fence, when the w4nd, no longer meeting with the obstruction, allows sand to be deposited Fig. 1.— Drifting sand as affected by a solid fence. in this channel, and it fills up, covering the fence. Similarly at the ends of the fence the wind currents are increased and the sand is scooped out. If the fence is raised so as to allow a space beneath, the sand is rapidly scooped out below. The same result occurs beneath buildings, trestles, or other works which allow a space beneath, L^tr:^^ Fig. 2. — Drifting sand as affected by an open, inflexible obstruction. through which the wind rushes with increased force. If. however, the obstruction is not solid, but more or less open, as a pile of brush or a bunch of grass, the action is entirely difi'erent. The wind passes through the obstruction, but with decreased velocity"; hence, sand is deposited within the obstruction. No excavation takes place in front Fig. 3. — Drifting sand as affected by an open, flexible obstruction. or around the sides. If the obstruction is stiff and inflexible like a sand fence, the sand is deposited on both sides (tig. 2), the windward slope being gradual and the lee slope more abrupt. If the obstruc- tion is tlexible like a bunch of grass, most of the sand is deposited in the lee (tig. 3). Of course there are all gradations between the two classes, and various circumstances may modify the usual action. It may be further stated that when the wind is blowing up an FIXATION OF DUNES. 13 incline, the surface velocity increases with the steepness. A small object is easily blown uphill. But when the wind l)lows down a slope, eddies form which usually produce a current uphill at the surface. Thus it happens that while small bodies can be blown uphill easil}^ it is not often that they are blown downhill, but must fall from their own weight when the slope is steep. The fact that the velocity of the wind at the surface on the windward side of a dune increases with the slope results in producing- a normal incline, which represents a bal- ancing of forces. Usually this incline is quite gradual compared with the lee side of the dune, where the slope is the greatest at which the sand will remain in place — about 30°. Sand can be removed from one place to another farther on b}' placing a suitable obstruction above, with a space between it and the surface of the sand, which will increase the wind velocity at this point. Sand may be tilled in at any point by interposing an open obstruction, such as brush or a sand hedge, or by planting grass. The practical appli- cation will be referred to farther on. ARTIFICIAL FIXATION OF DUNES. The fixation is most permanent when the dunes are covered with forest; hence, forestation is the ultimate aim wherever possible. But there is a narrow strip of territory just back of the strand where trees will not grow on account of the exposure to the severe winds and the action of the ocean spra}-. The width of this strip depends upon local conditions and may vary from one to several rods. The force of the wind is influenced by the character of the coast. Expe- rience soon demonstrates how near to the strand a forest ma}^ be produced. When the work of fixation is completed there will be a forest over the greater part, but a strip along the coast remains which must be permanently held in place by some other method, usualh^ by the plant- ing of grass. When the forest is once established it is cared for and preserved according to the usual methods of forestry'. Usually it is impossible to establish a forest directly upon the sand dunes either by sowing the seed or setting out 3'oung trees, because the drifting sand cuts the leaves and bark or uncovers or buries the young plants. Sowing the seed has been tried several times, but there remain of this work only a few" scattered patches of trees in protected places. It is therefore necessar}- to hold the sand in place by some kind of a cov^er- ing until the trees can obtain a start, when they form a covering themselves. The work of fixation is thus divided into two rather distinct stages: (1) Preliminary; holding the sand in place. (2) Permanent; establish- ing a forest. Upon the coast strip the work does not proceed beyond the first stage, but the maintenance of the covering in a satisfactory condition requires constant care. 14 METHODS USED FOR CONTROLLING SAND DUNES. BINDING THE SAND. There are many methods which have been employed at various times, but those now in successful use on a large scale may be considered under three heads: (1) Transplanting- sand-binding plants upon the dunes, sufficiently thick to form a living cover; (2) covering the entire surface with some inert material which prevents the wind from reach- ing the sand, and (3) covering the surface with a network of brush fence which, while not preventing the wind fi om reaching the sand, lessens its velocit}^ and prevents drifting. It may be remarked that numerous experiments have demonstrated the futilit}' of sowing the seeds of any plant directly upon the unprotected surface of the bare sand. These methods, as the}^ have been finall}^ elaborated, will now be described. For the historical development and the description of special methods to meet unusual conditions, the reader is referred to Gerhardt's book previousl}' mentioned. BINDING BY MEANS OF GRASSES. Various plants for binding the sand have been tried, but none have been found so successful as grasses. Willow cuttings have been emplo3'ed in a few cases, but their use has not proved satisfactory. Of the grasses the species used almost exclusively is beach grass {A/n- mo2)hila arenaria Link), shown in Plate I, frontispiece. A kind of wild rye {Elymus arenarius L.) has been used occasionall3^ Beach grass grows naturall}^ on the dunes all along the north Atlantic coasts of both P^urope and America as far south as Morocco and North Carolina. It grows in clumps to the height of one to three feet and spreads by means of extensivel}^ creeping underground stems or rhizomes. An important character of beach grass is that it grows with most luxuriance where the sand is drifting. In quiet sand it persists for a few 3^ears but gradually dies out. The drifting sand seems to supply the conditions for continued rejuvenation of the growth as the sprouts force their way up through the accumulating sand. Transplanting. — Beach grass may be transplanted in the autumn or spring ; in the autumn from the time it is mature, which may be as early as September, until the ground freezes, and in the spring from the time the ground thaws until growth starts. The grass is usually transplanted in the autumn, because at this time the requisite labor is more easily obtained, and furthermore it is then easier to pick out the individuals that are at the right stage of growth. It is best to choose moist or foggy weather, as the plants are more certain to grow, the danger of desiccation is less, the sand being damp it is more easily manipulated, and the work can be performed much more comfortably^, BINDING SAND WITH GRASSES. 15 as the fl3'ing sand .seriously interferes with planting during- dry- weather. The plants chosen for transplanting should be two years old and have at the base one or two nodes. The roots spring from these nodes; consequently at least one node must be present. More than two are not necessary and would be a waste of material, though they do no other harm than to interfere with planting in proportion to their num- ber. One-^'ear-old plants are not strong enough and have not devel- oped the nodes sufficiently for transplanting. Plants more than two years old are proportionately lacking in vitality and do not throw out roots with sufficient vigor. With some experience laborers are able to distinguish at sight plants of the right age. If the grass is grow- ing in loose sand and has not l)een covered deeply, it may be pulled up by hand. But usualh' it is neces- sary to cut the rhizomes below the surface of the sand, after which the plants can be easil}" pulled up. The method of procedure is for the workman to seize a suitable clump of the grass with the left hand and with a spade held in the right hand strike into the sand in such a manner as to cut otf the rhizomes below having one to three nodes at the lower end (PI. VII, fig. 1). The bunch is then pulled up and placed in a pile or under the left arm. When a bundle has accum- ulated, it is tied up and is read}^ for use. The spade used is a light tool special!}^ made for the purpose, with a sharp edge or point and a short handle. Sometimes an ordinary spade, such as is used in dig- ging, is put to this service. If the grass for transplanting is taken from the dunes that are to be fixed, care should be taken not to remove too much from one place and allow the wind to make a blowout. It should be chosen from places where the grass is growing too thickly. The arrange- ments should be such that the grass can be planted soon after being dug or the roots may dry out too much. For the same I'oason it is best to dig the plants near the place where they are to be set out, thus reducing the distance of transportation. The grass ma}' be set out in various ways, but the method which seems to be most satisfactory is as follows: The planting is done by two persons working together. One prepares the holes and the other inserts the grass. The holes are made with a spade specially con- structed, as shown in the illustration (fig. 4). The blade is rather heavy and has a sharp edge l)elow. The operator lifts the spade by the cross bar or handle with ])oth hands, and allows it to drop into the sand mostly by its own weight. He moves the handle back and forth once 17170— No. 57—01 2 Fig. 4.— Spade used for planting beach grass. 16 METHODS USED FOR CONTROLLINO SAND DUNES. or twice, or until the blade has been worked down throuoh the sand to the required depth. This makes a V-shaped opening in the sand 8 to 12 inches deep. The sand must l)e moist enough to retain its posi- tion or this method can not be used. The second worker now takes a portion of grass sufficient for one planting and places it in the hole, flattening out the bunch properl}'. The first worker puts the spade in the sand just behind the bunch, pushes the sand up tightly against the grass, and the operation is completed (fig. 5). The grass can be set out quite rapidly in this manner (PI. VII, fig. 2). Arrangement of the 2)lantation. — If the dunes are alread}" partially covered with beach grass, it may be necessar}^ to plant only here and there in the bare places to prevent excavation by the wind or the formation of blowouts. If the sand is bare or covered with onl}^ a scattering growth, it is necessar}^ to plant systematical!}' . The most common method is to set the plants in rows. In Germany they are set in squares, the quadrat system, which will be described under methods used in the Kurische Nehrung, When the gi'ass is set in rows, the ))unches are placed so that they alternate in adja- cent rows. Ordinaril}^ the rows are fairl}' straight and perpendicular to the prevailing direction of the wind. In an extended area, where there is a succession of dunes and depressiions, the rows ma}^ .•■-■■.•;::•;.;•■■-■ follow the contour lines. Rows in the direction FIG 5.-Method used in ^^ ^^^^ ^-^^ ^\^oxM be avoided, as a channel will planting beach grass. ' be formed between. In broken dune areas the plantings are made between the dunes and along their slopes, but leaving the tops bare (PI. IV, fig. 1). Usually there is no preparation of the dunes in the way of leveling or filling, as it is found more economical to allow the wind to do this work. The idea is to accumulate sand in the channels and hollows and allow the wind to blow^ ofl' the tops of the hills. To aid in leveling the high places the grass is removed from these so that the wind can have free access. No planting may be necessar}^ in the low places where the sand has been blown off down to moisture, as such situa- tions support considerable vegetation. The planting is begun at the base of the slopes and proceeds toward the top, as it is the lower por- tions that are eroded the most rapidly-, for the reasons stated when discussing wind velocity. The thickness of the planting depends upon local conditions. If it is necessary to accumulate sand rapidlv, as in filling a channel, the grass is planted in large bunches placed closely together; but where the sand is easily accumulated, the grass is set thinly to prevent its being covered. Under average conditions the rows are 15 to 18 inches apart and the plants about a foot apart in the row. The amount FOKMATION OF BAKKIER DUlsrE. 17 of grass in a bunch is about what can be easil}^ taken in the hand and may consist of four or five stalks. Formation, of the harrier dime. — The grass planting previousl}^ described applies particularl}" to the large dune areas near the coast. Fuj. 6. — Diagram showing in cross section the successive steps t:iken in forming a barrier rtunc. strand is at the left. The where this process is preparator}- to the planting of trees. The function of the grass has been fulfilled when the forest is established. As stated in an earlier paragraph, there is a strip of sand along- the 18 METHODS USED FOR CONTROLLING SAND DUNES. coast just back of the strand which presents conditions unfavorable to forest growth. Here it is necessary to hold the sand in place perma- nently by means of the grass. To do this requires constant super- vision. Through various causes bare spaces are likelj^ to occur which must be replanted to prevent the formation of blowouts. Sometimes the bunches must be thinned, as the presence of two large adjacent bunches ma}^ cause the wind to draw through between them and form a channel. .Strand ^- -f-.-f -^'.'^ i JfcaM-^JM^ Fig. 7. — Rc'ijairiiig a small breach in a barrier chine by planting grass. On the Kurische Nehrung in Prussia and along the southwest coast of France it has })een found advisable to form an artificial protecting dune extending all along the sea in front of the forest (PI. VI, fig. 1). This dune is produced b}^ accumulating the sand rapidly so as to form a long ridge (fig. 0). For this purpose brush fences, which consist of rows of brush or rough branches driven into the sand firmly but rising above the surface about 30 inches, are used. The tops should he on a level. Two such rows are placed about 6 feet apart. These fences allow the wind to pass through, but reduce its velocity, and hence sand is deposited within and on both sides. When the sand has reached the top of the fences, a second pair is placed above. When a ridge has been formed, beach grass is planted in rows parallel to the crest. At first, plantings are made along the slopes and a short distance in front toward the strand. As the sand accumulates, the grass is planted far- ther to the windward. Finally the protecting dune assumes a com- paratively permanent form, with a long slope to windward (toward Fk; 8. — Repairing a larger l)reaeh b> means of sand fences. The diagram represents a cross .section of a dune with two rows of sand fence parallel to the dune and cross rows extending from the outer row to the broken face. the sea) of 4 to 5 degrees, or about 1:9, and a steep slope on the lee side of about 1:2 (PI. V, fig. 1). As a matter of fact, the windward slope is often much steeper — as much as 1:6 or even 1:4. In practice this protecting dune must be established upon an area more or less broken by dunes of irregular shape. The ground line for the ridge is laid out to follow the coast in a general way, but to avoid all sharp bends or indentations of the shore line. The hollows and channels are filled up to the desired height, while the peaks and any small dunes lying in front are denuded of grass so that they are BINDING SAND WITH HEATHER. 19 ultimatel}' removed by the wind. Such a ridge protects the forest or arable land lying- in the lee, but requires constant supervision to keep it in repair. The danger is from encroachment of the sea during storms, especially in winter. A single severe storm may break through and destroj^ several rods of well-built dune. Such a breach must be repaired as soon as possible, or the wind will still further erode the unprotected sand and enlarge the opening. These l)reaks are best filled in by means of sand fences (tigs. 7 and 8 and PI. IV, fig. 2). It may be mentioned here that reclamation of sand dunes on a large scale is carried on in Europe b}" the general governments, as private individuals lack the necessary unity of purpose. This will be touched upon under the head of the particular regions visited. BINDING BY MEANS OF HEATHER. As stated previously, it is necessary to hold the sand in place while a forest is being established. Near the seacoast this is usually done by planting the beach grass, which is found growing wild upon the dunes. There are, however, vast stretches of inland dunes where beach grass does not grow, and the cost of transportation renders this method less economical than others. When fixing the sand is but preliminar}" to planting trees the method used depends upon the relative cost. Along the coast, where the fixation is permanent, the planting of beach grass is the only method which meets the requirements, and hence it is used even when it becomes necessary to import the plants. For a temporary covering any cheap inert material which meets the condition, such as brush, straw, or sawdust, may be used, but by far the most satisfactory material in northern Europe is the heather ( Cal- luiia vulgaris Salisb.). As it is a common plant in the sand-dune regions this method is used in the central portion of the Netherlands and in the interior regions of Denmark (PI. Ill, fig. 2). The heather can be used also in areas near the seacoast, as in western Denmark. Laying the heatJier. — The heather is cut off with scythes, spread over the surface, and held in place by a little sand. The scythe used for mowing is short and somewhat resembles American l)rush scythes. The heather is then tied in bundles and carried to the place where it is to be used. Sometimes it may be necessary to transport the bundles some distance, as the heather grows usually only in the low places between the dunes, or at least it is here that it grows in sufficient luxuriance to be cut profitably. Since the heather is not planted, it is not necessary to use it immediately after gathering, as in the case of the grass. The plants are spread out ffat upon the surface, overlap- ping each other in the rows, and are held in place b}^ being partially covered with sand.- The surface is not prepared, except that small inequalities are leveled so that the wind can not get beneath the layers of heather (PI. II, fig. 1). 20 METHODS USED FOR CONTROLLING SAND DUNES. The heather is also used in road making. The roads through the dunes are laid out and graded in the usual manner, after which heather is laid thickl}^ in courses upon the surface, thus preventing the wheels of vehicles from sinking into the sand (PI. II, tig. 2). BINDING WITH SAND HEDGES. Sand hedges are used for binding when other methods are not prac- ticable, or where the sand is drifting with especial force, or where it is desired to accumulate sand with rapidit3^ In general this method involves the use of some inert material, like brush or rows of stakes or reeds, which projects above the surface of the sand and reduces the velocit}^ of the wind without causing deflecting currents, which erode the sand. The entire surface of the sand is not covered, but the action of the wind is hindered sufiicientl}^ so that the sand present remains in place and additions from the strand or from neighboring unprotected areas are accunudated (PL IX, figs. 1 and 2). The sand fences or hedges are made from brush obtained in the forest. The branches are cut into pieces from 18 inches to 2 feet long, with sharp ends. The ends are sharpened by the slanting stroke which severs the stick. The side twigs are cut off roughly. These stakes are driven into the ground in rows, or, still better, in squares, thus catching the sand from all directions. The stakes project above the surface about a foot and should be on a line at the top, parallel with the general plane of the dune surface. The size of the squares depends on the tendency to drift, and varies from 9 to 12 feet. The rows should be at right angles to the direction of the prevailing wind. On dunes near the shore the rows should run parallel to this, with the short rows perpendicular. In covering a surface the long rows are first placed and the squares made by inserting crossrows between. The stakes should be close enough together in the rows so that the average width of the space is about equal to the average diameter of the stakes. The size of the stakes varies from half an inch to 2 inches (PI. IX, fig. 1). The common reed of Europe is utilized in the same manner. It is cut into the proper lengths and the pieces are set out in rows by about the same methods used in grass planting (PI. IX, fig. 2). As previously stated, sand fences are used to repair breaks in protect- ing dunes, to fill channels previous to planting grass, or wherever it is necessary to accumulate sand. In these cases it may be advantageous to have the fences higher than when they are intended primarily to bind the sand. Sand fences are sometimes used along the base of dunes near the strand, where grass will not grow on account of occasional high tides (PI. VIII, fig. 1). In place of sand fences heather or brush placed in rows or squares and held in place by a little sand thrown over one edge is sometimes used. ES'IABLISHING A FOREST. 21 FORESTATION. The processes previousl}^ described are as a rule only preparatory to establishing- a forest. When the dunes are covered with trees the}' are permanently fixed, and the trees being cared for according to the usual regulations pertaining to forest management become a source of revenue to the Government. It appears that most of the large and troublesome dune areas along the coast were at one time covered with forest, not- ably Holland and the Kurische Nehrung, but through lack of foresight these areas were de- nuded of forest and ere long were converted into wastes of drifting sand. Some attempts were made in the early part of the last century to re- forest these areas b}' sowing the seed of forest trees. These trials all resulted in failure, although there are here and there in protected situations small and stunted groves which sur- vived. It has l)een proved that the only satisfac- tory method of establishing a forest in the north- ern dune areas is by setting out 3'oung trees, after the sand has been fixed b}^ one of the methods described in previous paragraphs. In Gascony on the southwest coast of France, however, the forest has been successfully established from seed under conditions which will be described when speaking of the methods used in that countr}". The trees used are mostly conifers, the species depending upon the locality. In the Netherlands Pin us ((ustrtaca and P. hiricio are most successful on the coast and P. sylve-stris on the interior dunes; in Denmark Plnu.s mont per acre. « Sur la fixation des dunes dans I'ouest et dans le nord de la France. Extrait des Comptes Rendus de I'Association Fran(;aise jxHir 1' Avancement des Sciences. Paris, 1900. FIXATION" IN FRAlSrCE. 31 Mr. John Gifford, who has examined the dune region of the Landes, gives an account'^' of the methods used in the original work of recla- mation, which is here appended: A littoral dune was constructed straight along the shore from the mouth of the Gironde to Bayonne. This dune is the secret of all success in the fixation of shift- ing sand. It is simply a bank of sand of certain dimensions, with a certain slope suited to the condition of affairs. This protective, or littoral, dune is formed as fol- lows: A double fence is constructed of brush, or of imlisades driven in the sand. This stops the sand which comes from the ocean. Soon a ridge of sand forms, equal in height to the fence. A double fence is used, as it gives breadth to the dune and stops the sand which blows through the fence on the ocean side. As soon as a ridge of sand is formed as high as the fence, the old fence is pulled up or a new one built on top, and so on until a dune of the height desired is formed artificially. The proper height of a protective dune is 33 feet. It should slope 25 degrees toward the sea, and may be 60 degrees ^ on the land side. The dune must be at least 300 feet from high-water mark. After the dune has reached the proper size, it is kept in shape by the sea marram {Psamma arenaria).'^ This peculiar plant, called gourbet in France, is exclusively used for fixing the sand on the littoral dune. It has long, much-divided rhizomes, and will grow well only when covered with fresh sand. The dune must always be kept in shape. If sand accumulates in any one spot in undue amount, a draft is formed, which may end in a breach of the littoral dune. "Gardes cantonniers" are stationed along the dune to watch it closely, and here and there on this long, straight sand bank groups of men and women may be seen digging up the gourbet in places where it is too thick and planting it where needed. Constantly the dune is watched and mended; the forest, villages, and fields in its lee are depend- ent upon it, and it in turn is dependent upon the humble but persistent gourbet. After the formation of the littoral dune comes the work of planting in its lee. The surface of the sand is covered with brush arranged like the slates on a roof, with a shovelful of sand here and there to hold it down. Then the seeds of Pinus maritima are sown, with seeds of other plants to shade the young pines, and seeds to attract insec- tivorous birds. The pines usually come up well and grow quickly, although close to the littoral dune they are gnarled and stunted by the salt winds. Thus the sands are fixed, and, although the forests do not yield a good interest in cash, they are of incalculable value to a large proportion of the people of Gascony; in fact, indirectly, to the whole of France. Fire lanes have been constructed across the dunes, and, thanks to the watch- fulness of the guards and the rigid enforcement of laws, fires are almost impossible. Very little cutting is done in these forests, the revenue coming mainly from the resin industry. Owing to a lack of roads and insufficient means of transportation on these dunes, only the most valuable timber is marketed, after being tapped for resin. If it is desirable to remove a tree, it is bled to death before being cut. All other trees are tapped very carefully, and are in no way injured by the process. In fact, bled timber is considered superior to unbled in France. The Hague method of orcharding is used, a system which does not injure the tree, but gives a resin of bet- ter quality and more abundant turpentine. Another article, however, could be written on the French method of turi^entine orcharding. Other industries have started, the people have improved, and the country is more fruitful and beautiful, so that through the agency of trees a new province has been practically added to France. «The Control and Fixation of Shifting Sands. 1 the Engineering Magazine, January, 1898. b There is some error here in the angles given for the slope. The windward slope is from 4 degrees to 14 degrees, and the lee slope about 80 degrees. c Another name for beach grass {Ammophila arenaria). 17170— No. 57—01- — -3 32 METHODS USED FOR CONTROLLINCi SAND DUNES. SUMMARY. Extensive and systematic work is done by various governments in Europe for the purpose of reclaiming waste dune areas. The object ma}^ be to convert this waste into a productive forest, or to prevent the encroachment of the sand upon valuable property. The sand is first held in place b}^ some inert covering or a plantation of grass, and afterwards a forest is established by transplanting young trees. Trees will not grow in the immediate vicinity of the ocean; hence a narrow strip along the coast must be permanentl}" held in place by means of a sand-binding grass. The best grass for this purpose is beach grass {Amrnophila arenaria)^ which grows naturally along the sandy seashores of the North Atlantic coast. The same species grows along the shores of the Great Lakes and on the Atlantic coast of the United States as far south as North Carolina. The grass is transplanted in rows or squares in autumn or spring. Satisfactory results can not be produced by sowing the seed of this or of other plants directly upon the unprotected sand. Where heather grows in sufficient abundance this is cut and laid upon the surface of the sand. The third important method for preventing drifting is the use of sand fences. These consist of rows of rough stakes or pieces of brush driven into the sand and projecting above the surface from 1 to 3 feet. For holding the sand the shorter stakes are placed in squares of 9 to 12 feet, forming a network. For accumulating sand in hollows or repairing breaches in a protecting dune the high fences maj' be used. Solid fences are not used. The drifting of the sand having been prevented by one of the above methods, young trees are set out to form the permanent covering of forest. In northern Europe no satisfactor}" results have been obtained in establishing a forest by sowing the seed, but in southwestern Fmnce a forest was produced by sowing the seed of Ptnns maritima upon the sand and covering it with brush. The trees used are: In the Netherlands, Pmus austriaca and P. laricio near the coast, P. xylvestris on the interior dunes; Denmark, Piinis montana near the coast and Picea excelsa (preceded by Pinustnontana) on interior heath land; Germany, Pinus montana; France, Pinus inaiitlma. On the Kurische Nehrung and in other parts of Prussia, and in Gascony, a long barrier dune has been formed artificially to protect the land lying back of it. This is kept in repair bv planting beach grass and b}' the use of sand fences when necessary. PLATES. 33 DESCRIPTION OF PLATES. Plate I. frontispiece. Beach grass {Ammuphila arenarin Link). Drawing from her- barium specimen. Plate II. Fig. 1. — Inland dunes near Barneveld, the Netherlands. In the background the dunes have been covered with heather to prevent drifting and afterwards set out with Pinus sylvestris. In the foreground the pines have been planted without a covering of heather, as the sand is here moist enough to prevent its drifting. Fig. 2. — Inland dunes near Barneveld, the Netherlands, showing road in process of construction through the plantations. In the background the dunes are covered with heather. In the foreground is the road, the sand being ridged up with ditches at each side. Upon the sand is placed heather in a thick layer. This prevents the wheels of vehicles from sinking into the loose sand. Plate III. Fig. 1. — Inland dunes near Barneveld, the Netherlands, showing a plan- tation of Pinus sylvestris on a covering of heather. The sand is first covered with a layer of cut heather to prevent its drifting. Fig. 2. — Unreclaimed sand dunes near Alkmaar, the Netherlands. In the foreground is a low area partially covered with heather. In the interior such areas furnish the heather, which is cut and laid upon the surface of the sand to prevent its drifting. Plate IV. Fig. 1. — Plantation of beach grass upon the dunes near Oxbol, Denmark. This shows how the plantations are made along the lower places and part way up the slopes of the dunes, the tops remaining unplanted. The grass will be planted somewhat higher on the slopes as opi^ortunity permits, but the tops will be denuded of grass to facilitate the removal of the sand by the wind. Fig. 2. — Barrier or protecting dune south of Arcachon, France. To the left beach grass has been planted in rows j^arallel to the beach. In the center is a sand fence, placed to repair a breach, which is now nearly covered with sand. To the extreme right is the forest in the lee of the dune. Plate V. Fig. 1. — Lee slope of a portion of the barrier dune south of Arcachon, France. Since the dune has been fixed on the windward slope, the advance of the sand inland has been very slow, as shown by young trees growing along the slope. Fig. 2. — Unreclaimed sand dunes south of Arcachon, France. The stumps are the remains of a forest which has been covered and again uncovered by an advancing dune. Plate VI. Fig 1. — General view of the barrier dune south of Arcachon, France. This dune stretches along the coast from Arcachon to Bayonne, about 75 miles, and protects the forest of Pinus maritvma in its lee at the right. The ocean is seen at the left. This dune was formed artificially with the help of sand fences and beach grass and is now held in position by the same means. [From a pho- tograph by Mr. E. Duregne.] Fig. 2. — Unreclaimed sand dunes south of Arca- chon, France. The sand is drifting badly at this point. Here and there a snail hillock is held in place by a bunch of beach grass. Plate VII. Fig. 1. — Laborers digging beach grass near Alkmaar, in the Netherlands. The instrument used for this purpose here is a spade with a rounded point. The grass is obtained upon the dunes where it is growing naturally, by thinning out the bunches. In the background may be seen the unreclaimed dunes partially covered with vegetation. Fig. 2. — Laborers setting out beach grass upon the barrier 35 86 METHODS USED FOK CONTROLLING SAND DUNES. dune at Rossitten, on the Kurisehe Nehrung. At the right is the overseer. The grass is set in squares or ' ' quadrats. ' ' The position of the rows is determined quite accurately by stretching a line between two poles, one of which appears in the illustration. One laborer makes the holes with a planting spade, while another sets the grass. At the left may be seen a bundle of the grass ready to be set. Plate VIII. Fig. 1. — Protecting the base of a barrier dune by means of two rows of sand fences. Storms had eaten away the fa,ce of the dune and the fences are placed to accumulate sand, after which grass will be planted. [From a cut in Gerhardt's Diinenbau.] Fig. 2. — Protecting a road through the dunes, on the Frische Nehrung, Prussia. The road is curved and the slope is held by cover- ing with a layer of reeds and placing poles upon these. [From a cut in Gerhardt's Diinenbau.] Plate IX. Fig. 1. — Shifting dunes held by sand fences on the Kurisehe Nehrung, Prussia. The fences are of brush placed in squares. Nearer the strand the brush is in rows parallel to the beach. [From a cut in Gerhardt's Diinenbau. J Fig. 2. — Shifting dunes held by means of sand fences of reeds, on the Kurisehe Nebrung, Prussia. Next to the strand the reeds are placed in rows parallel to the beach. Farther up on the dunes they are placed in squares. A roadway passes through at this point. [From a cut in Gerhardt's Diinenbau.] o Bui. 57, Bureau of Plant Industry, U. 5. Dept. of Agriculture, Plate II. Fig. 1.— Dunes Held by Covering of Heather. Fig. 2.— Making a Road in the Dunes. Bui. 57, Bureau of Plant Industiy, U. S. Dept. of Agriculture. PLAT£ III. Fig. 1.— Pine Plantations in Covering of Heather. Fig. 2.— Heather Among the Dunes. Bui. 57, Bureau of Plant Industry, U. S. Dept. of Agriculture. Plate IV. Fig 1.— Beach Grass Plantation Along Base of Dunes. FiQ. 2.— Beach Grass and Sand Fence on Barrier Dune. Bui. 57, Bureau of Plant Industry. U. S, Dept. of Agriculture. Plate V. Fig. 1.— Lee Slope of Barrier Dune. Fig. 2.— Remains of Once Buried Forest. Bui. 57, Bureau of Plant Industry, U. S. Dept. of Agriculture. Plate VI, Fig. 1.— General View of Barrier Dune. Fig. 2.— Unreclaimed Shifting Dune. Bui. 57, Bureau of Plant industry, U. S. Dept. of Agriculture. Plate VII. Fig. 1 .—Digging Beach Grass for Planting. Fig. 2.— Transplanting Beach Grass. Bui. 57, Bureau of Plant Industry, U. S. Dept, of Agriculture. Plate VIII. Fig. 1.— Sand Fences Protecting Base of Dune. 1 1 m :^ -J: ■tm 1 P ... ■ ■■ ' ■ ^' ' ■ * ''' - 1 Fig. 2.— Protecting a Road Through the Dunes. Bui. 57, Bureau of Plant Industry, U. S. Dept. of Agriculture. Plate IX. Fig. 1.— Shifting Dunes Held by Brush Fences. t^-^iJi'tt.j^ tAi «..tt,uKiUMi£iiiiiiMiittiJku«iiMhitteMiM^^^ ..^^: — Fig. 2.— Shifting Dune Held by Reed Fences. LEMr'OP J