EFFECTS OF WIND ON VEGETATION, AND NECESSITY OF WOODLAND SCREENS.

Nelson Examiner and New Zealand Chronicle, Volume I, Issue 44, 7 January 1843, Page 176

EFFECTS OF WIND ON VEGETATION, AND NECESSITY OF WOODLAND SCREENS.

The following valuable article, communicated by Mr. Swainson, we have extracted from the New Zealand Gazette .— "I shall not here expatiate upon the extraordinary effects of wind upon the vegetation round Wellington. Vegetables which produce luxuriant crops under the shelter of the Tinakori hills, cannot be even grown with advantage upon Thorndon flat ; not from the inferiority of the soil, but because they are either bruised or broken by our two prevalent winds, before they reach maturity. A garden* in the situation of Captain Smith's, might be made to produce, with the least knowledge of horticulture, all the prize vegetables advertised by that society ; while a garden upon Thorndon Flat, not two acres distant, would find it difficult, with the greatest scientific skill, to secure even one. In the latter situation, my English fruit trees have pot grown one inch higher in the last year; nay, they ate shorter than when planted, lor all their uppermost shoots are withered; while those of Captain Smith's, planted at the same time, have shot up luxuriantly. It is therefore quite obvious that a belt or hedge encircling or screening a garden upon Thorndon and the other flats, would render it ten times more productive than without such a shelter. "Although the winds in the valley of the Hutt are fax less violent than at Wellington, their effect upon vegetation is no less singular : except on the lands adjoining the beach, they are not sufficiently strong to prevent the cultivation of such ordinary vegetables as peas, beans, &c, which cannot be grown onThomdon flat; and the further these gardens are removed from the influence of S.E. gales, the more luxuriant do they become ; but even here screens are absolutely essential for growing pumpkins, melons, cucumbers, and the whole of this family, they otherwise wither and bear no fruit. Higher iip the valley the S.E. winds are much less felt than those from the N. and N.W., but yet both should be guarded against by a provident farmer, since their effects upon indigenous vegetation are far greater than I have ever witnessed in any part of the world. Wherever a passage is opened for the winds, by catting sway the forest, the shrubs and trees thus exposed to their boisterous violence become either stunted->or absolutely blighted. The leaves of the aborescoat ferns (excepting out 'spades) -wither in forty-eight hours, and th« plant itself ultimately

dies, or is laid prostrate. A palm tree, having had, in its former sheltered state, leaves nearly four or five feet long, will only send up others of one foot to. replace the former, which are withered by wind in a few days ; while the more exposed branches of several trees cast their leaves, and absolutely die. Such are the effects of exposing even the native plants to these rude gales, which would otherwise have ' Play'd round their head, but never reached their'— Jar*. " Having carefully remarked all these circumstances before commencing to clear my Hutt lands, I resolved upon ascertaining which plan would be the best for producing the most luxuriant crop. I laid out three fields, each of one acre, leaving a screen between each, another of three-and-a-half acres, with only a partial belt, and another of half an acre, completely surrounded with the forest, excepting, of course, a narrow entrance. *' My one-acre fields I found too small* from being too much shaded ; I therefore cut away the eastern side of the belt and part of the western, leaving the north and south entire. The two prevalent winds were thus in port excluded, or rather their force materially broken, and the crops open to the rising and setting sun. These sheltered acres are now covered with the most luxurious wheat I ever beheld, even in Sicily or Italy. The wheat grown upon my three-and-a-half-acre field,- being exposed to the N.E. and S.W., is so decidedly inferior, that its produce will not be more than two-thirds, or perhaps one-half, what we may expect from the former fields, although they all join each other, and were all sowed at the same time. The plants of wheat in the more sheltered ground averages from four and three-quarters to' six feet high, and each bears from six to ten, and even more, full-grown ears. " Lastly, the half acre fcefqre alluded to as nearly surrounded with lofty trees, is more adapted for garden vegetables and fruits than for grain, and has not yet been burnt off. I observe, however, that the N.W. gales rush into the opening left in that direction, and actually blow all round the area, so that lam convinced the entrance should have been on the eastern or western side. It will be quite useless to attempt the cultivation of any heavy, or bulky fruits, us oranges, apples peaches, plums, or even figs, in ground which is not thoroughly sheltered by a belt, even -more complete than that upon, the spot in question. .' ' *' 1 think it may be safely deduced from the facts I have now stated, thai laying out fields or enclosures of not more than two acres, each

being encircled by belts, is the most judicious system upon which land in windy, situations lean be cleared, since it is likely to insure a much' , larger crop than if the "fields were of" 'gMtft dimensions. This plan I have therefore insisted upon in my leases to tenants. It has this advantage, that those "sides of the belt which run N. and S. can always be cut away, if more exposure to the sun is required; but if that part lying E. and W. is removed, an irreparable waste, in my humble opinion, is committed, inasmuch as such screens, in the Hutt forests, are the growth of between two and three centuries."

Nitrate of Soda. — If a person's name be sowir on meadow grass with this singular substance, it will in a few days grow up very distinct above the rest. Nitrate of soda is sown by the hand at the rate of one cwt. per acre. Nothing is more certain than that corn is immensely increased by its use. On natural and artificial grasses, the crops are perfectly monstrous. How these decided effects are produced, is one of the inexplicable mysteries of chymistry. Besides being cheaper than any other manure, the cost of carriage is also less, as a load of three tons will dress sixty acres. The Coal Mikes or Lancashire. — It has been calculated that the available coal-beds in Lancashire amount in weight to the enormous sum of 8,400,000,000 tons. The total consumption of this coal, it has , been estimated, amounts to 3,400,120 tons; hence it is inferred that the coal-field of Lancashire, at the present rate of consumption, will last 2,470 years.