VALUE OF TREES

Wanganui Chronicle, Volume 75, Issue 178, 30 July 1932, Page 20 (Supplement)

VALUE OF TREES

FARM SHELTER BELTS CONSERVATION OF MOISTURE Shelter belts on the farm arc almost invaluable. They give shelter to stock; they save grain from the threshing action of the wind; they encourage growth by grass by conserving soil moisture; they save the maintenance of shelter hedges, and they entai no expenditure except the first cost. All. these good ponts arc fully recognised, except perhaps the conservation of moisture, and to emphasise this the following experiences are given. A few months ago, a field at Lincoln College on the south side of a low belt, of pines was sown in grass. Immediately after sowing the grass camo up thickly on the side of the paddock next to the trees, and extended out from the trees to a distance equal to three times their height The rest of the field remained quite bare until rain fell some three or four weeks after sowing. In 1919 tanks of water were placed in a field at varying distances to th*' south of a belt of pines 59 feet high, and the evaporation was recorded during the months of October, November, and December. It was as follows: Evaporation two chains from the trees equalled I.7in. of rain; evaporation five chains from the trees equalled 2.7 in. of rain; evaporation twenty chains from the trees equalled 2.9 in. of rain The trees therefore saved over an inch of rain for the first two chains and their effect reached for at least five chains. With higher trees the effect would doubtless have spread further. There are, of course, disadvantages as well as advantages :n shelter belts, and these disadvantages will be dealt with after special trees have been considerd. Homesteads and Gardens The following recommendations are based on numerous observations of old plantations in many localities. Nearly every homestead has a shelterbelt, but the trees are usually too close to the house. Shelter is wanted early and so the trees are plantd close in. After twenty years or so they begin to shade the house and garden. They cannot be cut down because th* place would be as exposed as ever. So they are left to shade the grounds from sun as well as from wind, or are topped at the cost of considerable labour. and with an almost complete des traction of their beauty. If this state of affairs has developed there is only one remedy. Top the trees now grow ing, and plant a new shelter-belt well away from the house, so that it may reach its full maturity without shut ting out the sun. Where new. homestead plantations are being laid out. there is one course of action that should always be followed, namely, plant two shelter-belts at the same time —one close to the house to pro vide immediate shelter, and the other far away. When the nearby trees become a nuisance they may be cut out without hesitation, in the knowledge that the far-off belt will provide adequate shelter from wind, without cutting off the sun. Distance from the House

The location of the nearby shelter may be left to individual judgment after consideration of the prevailing wind, the lay of the land, etc. The distant belt is more difficult to place, for we have to visualise the trees at their full growth and consider their effect then. A fairly tall pine or poplar will reach a height of about 100 feet, and on the flat in the latitude of Christchurch and at noon in midwinter such trees will cast a shadow c»f about 90 yards long. The outer belt of trees must then clearly be more than 90 yards from the houst on the north side and even further than that on the north-cast and nor’ west sides, if the. house is to get the morning and afternoon sun. Allow ing for the sun to roach the garden in front of the house, the nearest ' this permanent belt should be placed is about five chains away, and generally it should b • further than that. Taking an avo •of homesteads that appear to be p.casantly placed as regards their shelter-belts, it is found that the trees are about six chains from the. house on the cast, north, and west sides. Where tho house is on a slope this distance should, of course, be modified. On the south side they may he much nearer for there is no loss of sun to be considered and dryness of the farmyard is an advantage The ring need not be continuous. When there are no •strong south-east wind* on that side the trees may be loft, out • where, desirable the north side may be left open by prolonging the east and west sides, or gaps may be left to pro vide a view.

The area enclosed by such a shelter would approach ton acres Such an area broken up by cross plantations of smaller trees ar hedges to shelter special spots, or arranged to form small paddocks for grazing sheep, etc. would bo a valuable improvement to most farms. Variety of Trees For high shelter, pinus radiala. usu ally called pinus insignia, and the Lombardy poplar have proved most useful over a wide variety of cli mates and soils, as both are quick growing and hardy. Their disadvantages aro that the. pines sometimes blow over, they kill the grass under the shade of their branches, and they harbour birds. The poplars have no effect on the grass and rarely blow over, but their leaves are untidy in the autumn. Though not so desirable as the above, where conditions are too rough pinus mnricata can be used. F<v cross belts within the shelter ring, trees that, are easily kept down to I‘. o- 15 feet in height, and that lose their leaves in winter arc desirable. For this purpose the silver bireh. and except in dry soils the large-leaved, Lombardy poplar nave generally proved most suitable. A single row of these higb Shslle'

trees is all that is necessary. The single row is efficient as shelter, and trees thus planted have a better foot hold, so that they are less likely to blow over than those planted in wider belts. High and Low Shelter The outer ring of pines or poplars is designed to give shelter to the whole of a large area, and their effect is much greater 50 yards away than close underneath them. In fact, there is no more cutting wind than a nor’easter or a sou-wester blowing through the bare trunks of old pines that have lost their bottom branches. A second row of trees of a variety that wil retain its branches close to the ground is therefore a necessity. This variety may bo slow growing, for it will not need to function for 15 to 20 years, and it need not grow more than 20 feet high. Lawsoniana (Cupressus Lawsoniana) is the very best for thb , purpose, and is a handsome and grace ful tree that is easily procured and easily grown. It. however, demands more moisture than it can get on the, dry side of a belt of pines in a season

of drought. It should therefore be used only on the better class of land, and should then probably be planted on the rainy side of the tall belt of pines or poplars. Where conditions arc too dry for Lawsoniana, macrocarpa should be used. It is not so handsome nor so closely branched as Lawsoniaua, but it grows easily, and, when unharmed by stock, retains its bottom branches fairly well. For this close bottom shelter the Forestry Department has recommended African box thorn. It grows only 12 to 15 feet high, makes an exceedingly dense bushy hedge, its spiky thorns make it quite impenetrable to stock, and above all it will grow close to pines.

Spacing Trees If pines are grown in a single row for shelter alone eight feet between the trees is a suitable distance, and for poplars three feet, as this spacing will early give low shelter, and the alternate trees can be cut out as maturity approaches. Lawsonianas or macrocarpas used for the low shelter belt can ,be 10 feet apart, as they win not need to function until the pines lose their bottom branches, say, in 15 to 20 years, and by that time the branches of the second belt will be interlocked. African box thorn can be put in at three feet spacing, as this is intended for a hedge, not a row of trees. The distance of the low belt from the high one is an important matter, because the slower-growing tree tends to be smothered out by. th« faster one. Lawsonianas and macro sarpas should be perhaps 20 feet from the pines, and African box thorn half that distance. If the high shelter con sists of poplars, Lawsonianas need be only *lO feet and box thorn only six feet away, this last combination giv ing the narrowest possible belt. To let stock into even a mature plantation of pines or macrocarpas des troys the bottom branches, and so ruins the shelter. One of the advantages of the box thorn hedge is that it is itself stock-proof, and makes a fence on one side of the belt unncces sary after a few years. Poplars and box thorn will, after six or eight years, need no fence at all. Objections to Farm Shelter Belts Objections usually made to shelter belts on farms arc as follows: —(1) They occupy valuable land; (2) they entail expense in planting and fencing; (3) they cause a belt of dry land on their north side on which practically nothing will grow; (4) they harbour birds that injure crops. To meet these objections various points may be considered. (1) Th< occupation of valuable land occurs mainly where the shelter belt consists of several rows of trees. If only one row of high trees and one row of lowtrees are planted, the width of the belt between fences need not exceed twelve yards or even six yards if poplars and box thorn arc used. (2) The expense of fencing Is unavoidable, and must be set off against the advantage of the shelter. (3) The belt of dry land on the north side is worst if pines arc used, but this is offset by the value of shelter to stock. Where poplars can he used, the absence of spreading branches and the absence of loaves in winter allow the grass to grow quite close up to the trees, and a belt of poplars and box thorn does not cause the loss of more ground than it actually occupies. (4) The harbour ing of birds is much loss with poplars than with pines.

Location and Varieties for Farm Shelter Whore the layout of the land makes it possible, farm shelter-belts should of course run across the winds that are most prevalent in the given locality, and L-shapcd bolts are necessary when there are two injurious winds at right angles to each other. Finns radiata or Lombardy poplars for the high shelter and Lawsoniana. macrocarpa, or box thorn for the low shelter are the most suitable trees for shelter belts on the farm as well as for the homestead. Isolated blocks of trees in sharp corners of paddocks or in nieces of waste land have a special value, ns they not. only provide shelter, but can be used for the production of timber for firewood, fencing, or even for milling. Within an outer ring of nines, additional species, not sosuite-' for shelter mav bo planted, e.g., euca! yptn* viminnlis, and macrocarnn, or Oregons where the rainfall is over thiry inches, and vinos lari-io in dryesituations, or. indeed, any Iroe thn* doos well in the locality. Those trees may bo planted at Rft. or 9ft. infer vals, and they will grow into tnll straight, clean trees, providing usefn 1 timber for all farm purposes an-' greatly improving 11m appearan<‘< o‘‘ the farm. tlummary No attempt is made to combine ton bcr production with shelter belts. For homestead shelter two belts of trees may be planted. one close in for imine diate shelter, and another five or six chains away to provide shelter when the near trees become too high. The shelter belts recommended «on sist of two rows of trees, one for high end one for bottom shelter. The varieties mentioned as suitable for high shelter are pinus radiata and poplars, the latter only on heavier soils. Those mentioned ns suitable for low shelter arc Lawsoniena for moist Inn'’ macroenipn for drier land, and Afri can I' • ino .■ hoio a

hedge rather than a row of ti<»e.s desired. I'or subdivision belts round bon:« stcaos. silver birch and broadleaved Lombardy poplar are very suitnbie. Trees lor timber are best, plant* i pure in solid blocks in sharp corner* of paddocks or'other waste vieces of land.