Rapid Shelter from Minor Species of Trees

New Zealand Journal of Agriculture, Volume 75, Issue 4, 15 October 1947, Page 387

Rapid Shelter from Minor Species of Trees

By ,

M. SUTHERLAND,

Farm Forestry Officer, Rural Development

Division, Wellington.

A RTICLES on planting homestead shelter in the March, June, and ** August issues of the “Journal” have dealt chiefly with the formation of high shelter belts designed to produce effect over a maximum area of land around the home enclosure, and the trees considered for that purpose have in the main been introduced species. However, there are ways of obtaining good shelter around the homestead or on the farm without waiting for the growth of tall trees, and this article describes the use of some minor species in the formation of quick-growing shelter. .:

THE general use of exotic pines for -®- shelter has been the result, of the necessity for speed and ease of establishment of trees to be used for protection,' and both these attributes are obtained more readily with the com-monly-planted exotic species than with most native species. Pinus radiata fulfils those needs admirably in early years and adapts itself to most conditions in New Zealand, but it is now recognised that there are limitations to the use of the common pines and that more choice is available in type of shelter and species which can be grown under various conditions. Ways of Using Minor Species Minor species of trees or shrubs can be employed to form single-type shelter breaks of medium height, for which both native and exotic species may be used. Such species may also be used 'in shelter plans in which a temporary quick-growing belt ,is formed for shelter while the permanent high-shelter trees are growing up in its lee. Minor species are particularly valuable. as nurse trees to protect slower, more tender trees which can be planted in association with them. J' In remote, exposed places, where establishment of shelter is ‘•difficult, existing tree or shrub vegetation may

often be used for protection at first, and by careful training or trimming an effective shelter belt or hedge can be formed from most unlikely material for example, manuka. Such a protection may be merely temporary and not as effective as well-planned shelter but in many newly-formed homes in these times of material and labour shortages expediency and improvisation of material near a* hand are necessary to obtain speedy relief from wind and weather. Such means may be found among both native and introduced types of vegetation.

NATIVE SPECIES

New Zealand Flax A valuable and widely-occurring native species is the übiquitous native flax (Phormium tenax) , which is found in practically every region of New Zealand. Certain conditions are most < suited for its development—for example, . deep, swamp soil with the water table a few feet below ground levelwhereas in dry, shallow soil it remains undersized and unthrifty, but flax may be relied on to produce ordinary, good growth on all types of land used for farming. ' On many farms are places where usual shelter species are hard to grow because of wet soil conditions, dry and stony ground, or

erratic frosts, and in such areas one of the easiest plants to estab-

lish is the native flax.

It grows by the successive formation of flat “fans” of long, strap leaves, the bases of which are tightly folded on each other to make a firm shaft springing from the swollen, horizontal, underground stem, while the stiff blades spread out or interlace to form a semi-penetrable screen which breaks up air currents and deflects wind upward. Closely-growing flax can be used as a hedge for homestead shelter or for farm subdivision and will persist almost indefinitely, but it is also of great value as a temporary barrier within which permanent trees can be planted, in which case care must be taken that sufficient growing space is allowed; at least Bft. should be left between the line of flax and the new trees.

Growth Characteristics

When planted as a belt flax will produce effective shelter in about four years, eventually forming a screen 10 to 12ft. high. It is indifferent to salt winds and will grow in pure sand, so that it can form valuable shelter on coastal land. Stock will chew the young leaves, so it is necessary to protect the line of bushes by fencing, at least on the side open to stock; planting along a drain or just below the ridge on a steep face will save one fencing line. Browsing cannot kill out the flax, but heavy browsing will reduce its value as shelter and produce an ugly appearance.

No trimming or thinning is required for several years after planting, but after 10 or 12 years the bushes may have spread extensively toward the fence and require to be dug out. This spread is a disadvantage where bushes are used as shelter clumps around the homestead, and great difficulty is often experienced in removing them because of the long, strong roots which may

FLAX AS FARM SHELTER

go down 10ft. toward underground water. - Vigorously-growing flax will overtop other growth, but for a successful shelter belt and to prevent the spread of weeds the clumps should be kept clear of heavy grass growth, which in time appears to weaken the stand; that is most easily done if the bottom fencing wire is left off to allow grazing by sheep or pigs. . Will not Thrive in Shade Though flax., may be useful for shelter in many difficult situations, it. will not thrive . in . full shade ■ under trees, especially in competition with tree roots where the soil is poor and dry, so it is seldom of use as undershelter to . renovate old pine belts which have opened up, below. Where no other species is available, it may be possible to use it for this puropse under certain conditions in high-rain-fall areas if the ground, can first be broken up .well along a .strip on the sunny side of ‘the pines and at least 10ft. from the tree stems, so that the flax will escape competition with the dense root system of the trees. . However, an excellent plan in the formation of a quick shelter belt is to use flax ‘in combination with some light-foliaged, deciduous trees such as Lombardy poplar .or silver birch, or with secondary native trees such as lacebarks. The flax can be planted as one line, and the trees, widely spaced at about 10ft., planted later as a back line about 4ft. away. Equally well, if

planted at the same time, trees may be spaced through the flax line at fixed intervals and will grow above the solid basal flax screen, providing

a higher line of wind deflection.

Easily Established

To obtain rapid first shelter in places where tree establishment is difficult,

flax has the merits of speed and ease

in establishment. Plants can be estab-

lished most simply by cutting off and transplanting small portions of an older bush; these . consist of small .blocks of the thick, underground stem,

2 or 3in. square . and: bearing two, dr three small young fans,, each of which before planting out should be trimmed into a wedge shape, leaving the inner

and younger leaves about 2ft. long, with edge leaves cut down to 12 or 18in. Dr. J. S. Yeates, Lecturer in Agricultural Botany at Massey College, states that quicker growth is obtained by planting out seedling flax rather than ■ fans from old bushes. These should be two-year seedlings, well grown and about 2ft. high, bearing several leaves, which should be cut back to Ift. long before planting. These seedlings may be found growing in the vicinity of old bushes or can be raised in a garden bed from seed collected from a good type of shelter bush. Care should be taken to propagate only from tall-growing plants, with upward rather than drooping leaf growth, and from sparsely-flowering clumps, which maintain a denser leaf production. Where local shelter is required only for sheep or 'piggeries, the drooping-leaved forms- may provide more shade. To form a good flax belt seedlings or fans should be planted out in one line about 3ft. apart in clean, cultivated ground, or as alternate lines with sft. between lines and plants and the same distance from the fence. Under ordinary conditions a satisfactory shelter will be obtained in about four years after planting, forming a screen 5 to 6ft. high which with age will increase in density and height. As well as its shelter value when used as a belt, clumps of flax are useful in the initial planting of farm-

house environs to break the force of wind on corners, but care should be

taken to plant the original fan at least 4ft. from any building, as it will increase rapidly in size and ultimately its proximity to the corner will make its removal, when it' is no longer required, still more difficult.

Ngaio

Another indigenous minor species which makes excellent shelter in certain positions is the ngaio (.Myoporum laetum), which is easily grown and fairly rapidly reaches the dimensions of a small tree bearing a rounded crown of wide, spreading branches at any height up to about 15ft. Used as a single line of trees planted sft. apart, with the . crowns eventually just touching, ngaios form an attractive shelter belt, or they may be planted more closely, 2 to 3ft. apart, and side trimmed from early days to form a hedge.

The New Zealand ngaio grows best under coastal conditions, occurring from one end of the Dominion to the other, but as a quick shelter tree it has now been superseded largely by the Tasmanian species (Myoporum insulare), which is more rapid in growth and more adaptable to inland conditions. The introduced species may be distinguished by its dark green, serrated-edged leaves, the New Zealand ngaio having light green, smooth-edged leaves.

Both species favour sandy soil or pure coastal sand, but Tasmanian ngaio will flourish on inland loams and the native species thrives also on poor, dry clay loam of the greywacke rotten rock formation; both grow badly on wet soil. These species are impervious to salt winds, the foliage remaining green and fresh after heavy and persistent gales. However, if they are grown in clay soils, and the crown is left untrimmed to form a top-heavy tree, after heavy rain ngaios may blow over, their root systems pulling up the ground in the vicinity though the roots remain firmly embedded in the soil; if the trunk is left lying, it gives off vertical branches which grow up thickly to re-form the wind screen.

As is usual with coastal species, the young tips of ngaio branches may become damaged by frosts of 8 to 10 degrees, especially when growing inland, but recovery is rapid and new foliage is produced in a few weeks.

Growth Form

When left to grow naturally ngaio trees become heavily branched and somewhat open, so that some trimming is necessary to create a good shelter screen. Trimming is best started in the first year when the trees are 18 to 24in. high by lightly cutting back the lower branch tips; that stimulates the growth of more side branches if carried out twice or thrice during the first two seasons. The plant may then be left to develop its top growth naturally. , ,

In suitable localities of both

islands Tasmanian ngaio is one of the best subsidiary trees to produce rapid shelter around a bare home. It will form shelter 4 to 6ft. high in two years and grow into a tree of average height up to 15 or 20ft. with a spread of 12ft. in about six years. It can also form a satisfactory hedge 12 to 15ft. high which, by hard trimming every six or eight years after - establishment, can be kept to a thickness of 4

or sft.

A most useful quality of ngaio as a shelter species is its tenacity of life; it may be cut back hard to wood 1 or 2in. thick and in a few weeks it will put . forth strong, green growth

MINOR SHELTER

which in time forms woody branches as before. Trimmed hedges of 20 years’ growth are known, but at that age they tend to become rough and rather open.

Stock are not partial to either species of ngaio when they have plenty of feed and apparently no harm comes to them from chewing occasional fresh' leaves from a hedge, but where branches have been blown down in a gale when little feed was available in the paddocks animals have been fatally poisoned by eating the leaves. Therefore it is important to keep stock out of paddocks bordered by ngaio until branches have been cleared away after storms, and ngaio hedge trimmings should always be burnt. Plants should be protected from browsing by placing a fence well away from the trees while the foliage is still low.

Seedlings and Cuttings

Both species of ngaio are most easily grown from seed. Natural seedlings are often found around openly-grown trees, and they-can be lifted and transplanted in the garden for a year to increase the root system before being used for shelter belts. If seed is sown soon after it ripens in July on fine soil and lightly covered, seedlings may be ready to plant out the following winter.

For farmers who will take the time and trouble, cuttings may be grown by removing about sin. of the growing tips of branches; all leaves but the top three are stripped oil and the stem inserted in sandy soil except for about lin. at the tip. The cuttings must be sheltered from the sun by scrim or branches and kept moist until they root in a month or two.

Growing from cuttings is uncertain, but an easier method is to take cuttings about 9in. long in summer from mature wood of pencil thickness, place them slanting in a trench Bin. deep so that only about 1 in. is left above ground,’

firm the soil-against the stems, and keep them moist and sheltered. These should be rooted and grown sufficiently to be transplanted late in the following winter.

Whether grown on the farm or bought in as rooted cuttings or plants, ngaio stock should be planted as soon as it is taken out of the ground and must never be allowed to dry. Even after planting it is wise to water them for the first few weeks.

EXOTIC SPECIES Pampas Grass

In areas where it grows successfully pampas grass (Cortaderia selloana) has been evolved in' recent years as a useful dual-purpose farm crop. In the North Island and northern parts of the South Island the value of pampas as winter stock feed is recognised and the crop has been grown as standard practice in many districts, but in recent years not so much prominence has been given it as an aid to the rapid production of shelter on the farm. In Auckland Province pampas was first used for shelter or ornament, and from the partiality for it shown by stock arose the recognition of its possibility for use as feed. If follows that when used as shelter pampas grass must be securely fenced off from' stock, though it can withstand the damage and . renew easily the growth lost by being eaten off.

Another advantage is its rapid growth. In three years it will provide a dense shelter hedge up to 6ft. high, and even when eaten down in one winter’s grazing it will regrow up to 7 or Bft. during the next few months. An average height of 12ft. is attained by the grass, but how long plants of that size will keep their density is not known.

Additional qualities are its adaptability to many soils and climates and its ease of establishment if correct

methods are followed. Though for best growth it should be planted on fertile, well-drained soil, it can be grown on pumice land, on light clay, on some sandy and peaty soils, and on hillsides, but will not succeed on waste or weedy land without cultivation; having a long rooting system it can penetrate to a deep water table. The best production as fodder occurs in the warmer parts of the country, but the plant will grow sufficiently as shelter in all but the higher and coldest parts, and apparently is not influenced by frost when mature or by salt sea winds. ' .

Shelter and Grazing

For advantage to be taken of the double-purpose crop, its use as fodder must be well regulated by the farmer and the crop‘ must be in a position which will afford shelter to stock or to the homesteadfor example, a pampas belt can be. planted along a home paddock margin in a position to shelter the house from cold winds and at the same time be available for emergency feeding for the stock. Though the two purposes are compatible, pampas used for house shelter must not be grazed so heavily or constantly that growth is reduced sufficiently, to become ineffective; its value must lie in short periodic winter grazing or supplementary feeding in times of drought.

USES OF PAMPAS GRASS

For stock shelter the same limits need not apply, as it is only, toward the end of severe eating down when clumps are low that the grazing stock are bereft -of the shelter. . That, can be remedied. by having alternative belts placed strategically for successive grazing.

It is ' characteristic of pampas

that when the flowering heads are left on -.the plant the centre of the

elump gradually dies out. That can be prevented by allowing stock to graze in the belt for a short while when the flowering heads are youngabout February when they will ’ eat the heads in

preference to the leaves.

The crop should not be grazed until the second year after planting,, by which time it is established effectively as' shelter, and . after that a controlled grazing to eat down weeds, and prevent the accumulation of old growth should be carried out annually by opening a fence and allowing cattle to feed daily over a period. Plantations of pampas should be kept free of rank grass and weeds, which is most easily done in mature crops -by allowing young sheep access to clean up growth between the clumps.

Objections have been raised to growing pampas near the, homestead, as the large clumps may furnish shelter for vermin.

Propagation

Pampas grass belts can be formed by transplanting rooted sections directly from existing plants, but the safest method of - establishment is either by seedlings, bought in or raised in a farm nursery,, which have been lined out .for a year, or by rooted cuttings which have' been obtained by first breaking up mature plants into sections for propagation. These sections are lined out and cultivated in the garden nursery for a year, after which they are again broken up and the rooted parts planted out permanently.

Ground to receive pampas plants should be well cultivated beforehand, and the plants placed 6 to Bft. apart, according to the quality of the site, and 7 to Bft. from the fence. For successful establishment planting should be done in spring after late frosts and the area should be kept well cultivated for the first two years.

As a homestead shelter belt pampas has an attractive appearance and, if grazed intermittently, will preserve its strength and appearance. Clumps have been known to persist for 20 years, though it should be regarded as a more temporary shelter. In a mixed belt planted with a eucalyptus species or with deciduous trees such as English ash or oak it will act as a rapid under-shelter, but the trees must either be planted two or three seasons ahead of the pampas, so that they get beyond grazing damage, or be-large saplings when planted. Alternatively, such a mixed belt can be placed along a drain, but that may cause difficulty in grazing. Detailed information about the growth and use of pampas grass is to be found in past numbers of the “Journal of Agriculture,” especially useful information about shelter being that in the August, 1940, issue, page 93,

Bamboos

A similar type of shelter plant is the small-leaved bamboo (Arundinaria macro sperma) , which grows easily in the warmer regions of the North Island and can be grown in all but the driest and most frosty parts of the South Island. It is, especially useful for wet areas such as drained swamps and river-silt flats which are unsuitable fo’r the usual shelter trees or hedge species, but it is also adaptable to many types of soil and to flat or hilly areas.

Many kinds of bamboo are growing in New Zealand, but the most common one is the most suitable for shelter. This plant when fully grown reaches a height of 15 to 20ft. and a mature

EXOTIC MINOR SHELTER SPECIES

belt consists of many closely-grown, 2-in. stems which make a shelter impenetrable to wind and stock. However, stock damage it by chewing, so it is necessary to fence off the area to be' planted. In drained areas a belt can be planted along the lee side of the drain, with the bounding fence 9 or 10ft. from the drain. It withstands salt winds and is thus of value in coastal areas as an outside line for house protection, allowing tall trees and shrubs to be raised under its shelter as shown in the photograph at the head of this article. As it is fairly tolerant of shade, it will persist if necessary as under-shelter when nearby trees grow up. .

Control of Suckering

Bamboo requires no trimming, as the leaves are carried up on a clean stalk, but it suckers very freely and spreads quickly if unchecked. Where it adjoins grazing land the spread-is kept down by stock eating off the young shoots as they come near the fence, but where it abuts on garden land bamboo may become a nuisance. In such cases the spread may be kept in check by digging a ditch 18 to 24in. wide and up to 3ft. deep on the garden side. Another disadvantage of this species is the difficulty of eradicating a heavy growth.

Bamboo is easily established by planting out rooted younger shoots of old plants. Pieces of the clump 2 or 3in. square bearing three or four shoots are cut off with a sharp spade, the tops trimmed down to 18 or 24in. and these' sets are planted, preferably in cultivated land, about 2ft. apart and at least 4ft. from the fence. Rank grass should not be allowed near bamboo, hence the necessity for first cultivating the ground to be planted. If that. is done, in favourable ‘ soil a hedge will grow to a height of 5 or 6ft. in the first two years and provide a continuous shelter screen. Bamboo hedges exist which have remained effective for 20 years.

An added virtue around homestead areas is their ability to provide so dense a cover that weeds such as

blackberry and fern are unable to exist under the shade.

Tree Lucerne

Perhaps the most useful of all the minor species to grow for shelter is the tree lucerne (Cytisus proliferus), known also as tagasaste. It has been introduced in recent years from the Canary Islands,, and in _ a short time has firmly established itself in milder parts.

It may correctly be termed “the

farmer’s friend,” as its uses are so varied that it can provide mediumheight shelter belts, hedges, beefood, firewood, and soil improvement, without any indication of

its becoming a harmful weed.

Tree lucerne is very accommodating in its demands on conditions of growth; it occurs freely on coastal and inland areas throughout the North Island and, though at present it is growing only in scattered areas of the South Island, there appears no reason why it should not be adopted more widely for temporary shelter.

The value of tagasaste lies chiefly in its adaptability to poor . conditions where other shrubs and trees find difficulty in maintaining growth and in its prolific growth in poor soil. Under such conditions, where the planting of Pinus radiata is usually resorted to, tree lucerne will grow more rapidly than . pines in the ' first three or four years and produce better shelter. It flourishes in sand, but grows almost equally well in poor clay loams; it seldom grows in wet, sour areas or in very rich land, but is invaluable on dry, thin, and exposed soils. It is suited to most climates in New Zealand and withstands considerable degrees of frost and cold, but in areas of heavy rainfall it is not necessary to use it because better, permanent species can usually be grown.

Rapid growth occurs in plants from the seedling stage, and in two years they will give shelter about 6ft. high; if left to develop naturally, this species will ultimately form small trees 25 to

30ft. high. Tree lucerne grows prolifically, forming a spreading, lightlybranched, bushy head, and when grown sufficiently closelysay 4 or sft. apart in a single lineit will form an effective shelter screen, but it tends to open up at the foot, so that to preserve the leafy barrier to the ground it is necessary to trim the lower regions of the plant from early growth. When the trees are about a foot high the tips should be cut back for 2 or 3in. and a succession of side trimmings should be carried out during the growing seasonfive or six times in the first year— produce a solid base. o That may appear to involve frequent labour, but the soft growth can be trimmed extremely easily and rapidly with shears if done lightly and often, and the trouble involved is well repaid.

Adaptable Growth

Grown in a single line with the inner border trimmed up to sft., tree lucerne forms an excellent first shelter around the farmhouse, especially if the belt is placed along a ridge where shelter is . difficult to establish and where the rapid height growth is effective in deflecting prevailing winds upward over the house. If the trees are planted just below the crest of the ridge, it is possible to dispense with the basal thickening up process because the bank • stops any draught, though it is better to trim the inner branch growth for the sake of appearance from the house.

Treated as an ordinary hedge plant, tree lucerne will form a compact, evergreen, easily-trimmed and effective shelter. For that purpose plants should be grown 18 to 24in. apart and trimmed, from early regularly and frequently during the first two years, after which trimming is required only two or three times a year during the growing season. The top may be left to grow unchecked or levelled off when the required height is reached.

Hedges, which become twiggy and dense, can with care be kept down to a width of about 2ft. Tree lucerne maintains its rapid growth throughout its life, but that is short, and at 10 or 12 years trees may be expected to die off, sometimes assisted by attack by a borer, which is not harmful to house timber.

Use as a Nurse Tree

Because of its short life and light branching habit and foliage, tree lucerne. is perhaps the most suitable species for use as a temporary shelter to act as nurse in raising permanent shelter of valuable and less hardy species. In this way a lucerne belt can be grown rapidly where shelter is required, and after a year or so trees which are sensitive to wind in their early years, or which require cover from frost, may be planted in its lee.

USES OF TREE LUCERNE

For such purposes the permanent crop may be planted as an inner row 3 or 4ft. from the lucerne row and the over-topping branches of lucerne lopped off as required, or frostsensitive permanent trees may be interplanted among scattered lucerne plants, the light foliage of which admits sufficient light but acts as a screen in 1 frosty weather.. Most permanent species become established by. 12 years, after which the lucerne either gradually dies out or can be cut out, ' the wood providing very useful firewood, even when green. It can be removed with little trouble, in contrast to Pinus radiata, which until recently has been generally used in such cases to provide . quick shelter but which rapidly grows out of control, often becoming a menace to the house and requiring expensive measures to remove,

Pines give little back to the soil, but tree lucerne, being a leguminous species, carries nitrifying nodules on the roots, and as well as being . able to utilise nitrogen from h air . leaves sojl on which ~ . . ... . j J has been growing with improved humus and nitrogen content. Tree lucerne has an attractive appearance of drooping, spreading branches with soft, light green foliage and masses of white, fragrant flowers blossoming in very early spring , and providing the first early food for bees, It seeds prolifically on to nearby areas, and thus many belts of lucerne thicken themselves by continual replacement, but it does not become a menace to surrounding land, as 'seedling growth is easily eradicated, and if eaten by stock it is harmless.

The disadvantages of this species as shelter are its . purely temporary nature—it is more suited to house hedges or temporary shelter belts than to farm hedgingand its open-growing. habit, which requires that it be trimmed often .to preserve its density and, where grown as a “nurse,” to prevent excessive spread of its branches over the permanent species which it is protecting. Tree lucerne is attractive to stock, and belts or hedges must be effectively protected by fences to prevent animals reaching over to browse on young plants, though later sufficient clipping may be attained by allowing stock to browse it at the extremity of their reach. _ ' ■

Ease of Establishment

■ Tree lucerne is easily established, either by planting out one-year trees which have been well rooted in a nurserythough care should be taken to do that in damp weather, as the plants wilt easily and dry off — with almost as rapid results, by sowing fresh seed where the shelter is required. The ground should be worked over and the seeds sown about every 6in., pressed into the soil, and lightly covered. When germination is well advanced the seedlings may be thinned to about 18in. and the spare ones used in gaps.

Wild seedlings, which are to be found near old trees in summer and autumn, can be used to form new belts. When not over,6in. high they should either be lifted and immediately. lined out in a nursery bed to form better roots before being planted permanently after two or three months, or they should be wrenched on the spot and removed for, planting as required or dug up with a small block of soil attached and replanted immediately.

Seed ripens in April and May and should be sown when fresh in August or September. If seed is old, it should have boiling water poured over it and be left overnight, then spread to dry or mixed with sand before being sown.

A MECHANICAL TRACTOR STUMPER AT WORK