Value of Tree Planting

New Zealand Graphic, Volume XLVIII, Issue 18, 30 October 1912, Page 37

Value of Tree Planting

Growth and Preservation of Forests

By

HUGH BOSCAWEN,

Inspector of Forests

gVERY season brings floods in rivers and creeks, also droughts; both occur more frequently than formerly. By replanting and preservation of existing bush lands, these floods and droughts can be minimised. The aim of settlers in the past has been to get rid of the bush, and supply its place with grass. In many cases, the bush on the land has been the best crop that it is ever likely to grow, either because of the poorness of the land, or on account of the rugged nature of the hills. Great attention has been given by the Government to the growth and preservation of timber, also to the preservation of existing forests. There are large State nurseries that can raise millions of trees per annum. Each acre planted with foreign trees should produce about 25,000 superficial feet of marketable timber in 60 or 70 years. I speak of foreign trees because, with the exception of the Puriri New Zealand trees are too slow growing for profit. It is absolutely necessary to preserve bush for climatic purposes, so as to maintain the water supply required for the sources of rivers and creeks. Many countries visited by me which, at our time were thickly bush covered, portions have been cleared of forests, and are now barren wastes, or nearly so, with sudden floods in rivers, alternating with long droughts in summer. For example, parts of Palestine, China, Spain, etc., It was during my time in the

navy, on an Island not far from St. Helena — H.M.S. “Ascension,” so called because the inhabitants were under the

Articles of War—that I saw what could 'be done for a barren land by tree planting. When first I saw this island, the bare scoria cone looked very uninviting. Its shape not unlike a very large Rangitoto. Rain seldom fell, and there were no springs. The inhabitants, who were mostly convicts, worked in the naval y ard, and had to use condensed seawater to drink. It was decided by the naval authorities to plant the high volcanic cone in the centre of the island with trees. Before this could be done, soil had to be obtained from the adjacent West Coast of Africa. The soil was brought over as ballast and taken to the top of the cone by convict labour. A Scotch gardener was obtained, and trees were planted under his supervision, and watered with condensed water. The island being situated in the tropics, it did not take long for the trees to grow. The clouds were attracted by the green growth, and rain fell. It took a remarkably short time for the former dry scoria cone to become a beautiful green mountain. The last time I saw the island, there was a pretty naval hospital on a portion of the cone, grass and trees growing half way down, and fresh water fairly abundant in the dockyard, having been conveyed by pipes from catch water tanks on the cone. This is a positive proof of the result of planting bare hilltops to attract rain. It does not pay to reforest with native trees. Native trees make quick growth for the first few years, then thes’ become practically stationary, their growth being hardly noticeable. Puriri is the only marketable New Zealand timber that will mature in 50 years. All New Zealand trees require shade, especially in the beginning, and this ean only be obtained by fencing off old cutout areas, that have been partially

cleared; then the quick-growing undergrowth that springs up must to some extent be kept down by cutting. The young forest trees start growth at once, without injury to their roots by replanting. The necessary keeping clear each year of the shrub growth, costs money, and. moreover, this must be continued until the young forest trees have grown above the scrub. It is necessary to keep the roots of young New Zealand forest trees sheltered from the sun and wind, because

their roots are on the surface, and would rapidly dry up. The probable age of well-grown New Zealand trees run into hundreds of years. A good rata is estimated to be hundreds of years old. Kauri, over 1,000 years, rimu, 700, totals, 900, even kahikatea 500. I know of one transplanted kauri which was planted during my first visit to New Zealand, in 1870; it is now only 25 feet high. There is a good example of New Zealand bush in the parish of Titirangi, belonging to Mr. Atkinson. This young bush shows the growth of timber very well. The bush was burnt 50 years ago. and young trees of all sorts sprang up after the fire, and none of the young trees, such as rimu. totara. kahikatea. taneka, are now over 40 feet, most of them a good deal upder. If in suitable deforested areas, foreign trees were planted, such as oak. ash. various pines, many varieties of the Eucalypti, Sugar maples, walnuts, Spanish chestnuts, and other nut bearing trees apart from timber trees; this mixed forest would in a climate like that of Auckland, be giving a handsome return in 50 years. A return for money spent in a man’s lifetime. Thinnings from the plantations could be sold for railway sleepers, and fencing posts etc., and so the cost of planting and supervision could be kept down. It is only in the pole and sapling stages, w’hen crowded together in new plantations that trees make their rapid growth. If free circulation of air and space are given by thinning, then the trunk circumference begins to increase, the growth in height being slower. I would suggest the planting of puriri, and pohutukawa, on land near the coast north of Auckland. As both trees when young are touched by frost, they would not thrive further inland.

To conclude: — Ist. It is absolutely necessary that bush on hilltops and gullies should l>e reserved on account of water supply. 2nd. It is too costly and slow to replant areas with native trees.

3rd. Suitable foreign trees, if planted, do well in New Zealand, in a short time, and are therefore most economical for reforesting poor land.