New Zealand Times (PUBLISHED DAILY.) THURSDAY, NOVEMBER 23.

New Zealand Times, Volume XXXI, Issue 4890, 23 November 1876, Page 2

New Zealand Times (PUBLISHED DAILY.) THURSDAY, NOVEMBER 23.

We have had occasion to refer lately on more than one occasion to the importance of forest culture and preservation, and think the matter of such moment as to be worthy of additional consideration. The wholesale method of clearing vast areas of hill land at present in vogue, as for instance, the stripping of the hillsides in the Hutt Valley of every vestige; of timber is* a most pernicious principle; and although as yet we have not suffered any immediate inconvenience from the practice, yet when it is applied to, the unopened bush .lands all through the country the effect will most surely follow the cause, and we shall experience; climatic changes never . even dreamed of. The’ destruction caused by inundations in the valleys of the Arduohe, the Po, .and other

European rivers was distintly traceable to , increased surface drainage caused by cutting down the forests near their sources, and we do not see why we are to expect immunity from similar consequences if we persist in our present system of wholesale bush clearing. . In the hills the surface soil being generally of a light vegetable character, composed as it is of decomposed leaves, with the rock lying underneath at no great depth, is easily washed : away, and any attempt to reclothe our precipitous hillsides with forest growth when once denuded of their verdure and surface soil can only be futile. Marsh’s “Man and Nature” gives instances where whole districts have been ruined and depopulated, owing to the felling of the hillside forests, in addition to another inevitable result, viz., the great depreciation in value of lowlying properties in the valleys owing to floods. We direct attention to the preservation of the hillside forests not only because it is almost impossible to restore them if once destroyed, but also in that if conserved they are less liable to destruction froin natural causes than those on low-lying lands. The reason for this is apparent, inasmuch as the lowlying lands are naturally more hardened and compact, and much less moisture is found in the subsoil than beneath the comparatively loose surface soil of the hill-sides. The amount of moisture in the ground within reach of the roots of a tree is an important element in considering the question of its preservation, as it will have a far better chance of‘living and flourishing when the amount of moisture present and capable of absorption by its roots exceeds the amount required for the evaporation of moisture through the leaves. Having arrived at a conclusionthatif it is necessary to conserve forests, those most easily and beneficially —so far as immunity from floods is concerned—preserved are hill-side forests, it may perhaps be as well to consider some of the reasons which show the absolute necessity for conservation. Not only as preventing floods, but as arresting and retaining moisture in the soil, are forests most valuable, but by preventing the incidence of the sun’s rays on the surface, and checking the force of the winds, two chief causes of evaporation are removed, the greater part of the water not taken up by the roots of the trees and evaporated through the leaves finding its way by percolation, nature’s own system of subsoil drainage, to the nearest watercourses, and improving the condition of all intervening lands. Experience has shown that the destruction of forests on the watersheds of rivers leads to the formation of inland dunes, hills of moveable sand, which year by year increase in area and cover the adjacent lands. These; dunes readily absorb the rains, nqt much running off the surface, and their objectionable nature is easily ascertained by . a visit to : Lyell, Bay, where asea shore dune exists in all its unimproved beauty. The value of arboriculture as a means of removing these seashore dunes has been most, effectively proved on the Coast of Jutland. ' So early as 1539 sand plants were cultivated on the shore to prevent further drifting of the sand, and in 1779 the Arundo arenaria was planted with very beneficial results, animals destructive to them being destroyed. Ten years later plantations of forest trees, since proved to be the most valuable means of fixing dunes and rendering them productive, were commenced, and have been continued ever since. The planting of seashore dunes is now the practice all over Europe where they exist, the r best adapted for this purpose being r the Pinna Maritima, which has also been planted on inland dunes in France with equal success. The climatic influence of forest , vegetation should not escape our attention, for thb trees not only absorb heat in the day but give it off by radiation .at night, and transpire through their leaves the moisture imbibed from the low-lying moist strata of the earth, "which in the form of vapor moderates the amount of - solar heat falling on the ground. In a well and evenly wooded country, the cool air over those parts which are planted by its greater specific gravity sinks and displays the air over the open country, which is more heated and expanded, and this is probably one of the causes for the great variation in the temperature which occurs in New Zealand between day and night, as notwithstanding the wholesale inroads which have been made on the forests, we have still more than a fair proportion of timbered lands. , lib is a common thing to say that a place is green and cool looking; but the fact is that it is cool by reason of the surrounding vegetation. In any case it is incontestable that trees have an immense influence in moderating the climate of a country, and in addition there is no doubt that they affect the rainfall. Clouds laden with vapor pass over bare plains without discharging moisture, because of the want of absorbtive and radiative power, but when they reach a place where the air is chilled with radiation, rainfall is the immediate result. In a country blessed by nature and art with abundant plantations, the moisture instead of being retained in the clouds until it comes down in torrents, is more frequently precipitated, the showers coming at leas intervals, and being milder in their character. Forest destruction in Europe proves without doubt that the extent of barren lands—lands formerly cultivated, but now producing no crop, save perhaps some poor, grass—is alarmingly on the increase; and we in NeVv Zealand would do well to learn by example, and let the experience of others save us from falling into similar errors. A great advantage of forest cultivation is that when land is left in an undisturbed state, in course of time the grasses as they die, and the leaves; as they fall from the trees, so enrich the soil as to render it marvellously fertile by comparison with land under cultivation for a considerable period.' V,This is due to the soil beooming humus or vegetable mould, owing to the accumulations of decayed vegetablematter, and the effect of planting barren lands with trees, on the ground of mere profit only in the distant future, cannot be otherwise than beneficial. Although perhaps we are not so far advanced as to be able to support an expensive forest department in New Zealand, yet some system of control is absolutely needed to check the present destruction, and if the House of Representatives next session carries out its. evident determination of repealing the New'(Zealand Forests Bill we . only hope that some proper .and and efficient machinery will be provided in its stead. j