FOREST AND BUSHLANDS

Bay of Plenty Beacon, Volume 11, Issue 84, 24 September 1947, Page 5

FOREST AND BUSHLANDS

EROSION PROBLEMS CONSEQUENT ON CLEARING The theory that forest or bush-clad lands should be closed up or reserved to prevent soil erosion was attacked by Messrs. E. Bruce Levy, of the Department of Scientific and Industrial Research, Palmerston North, and P. D. Sears of the Soil Research Bureau, in a lantern lecture to members of the Hauraki Catchment Board and others at Te Aroha recently. Mr Levy said that he did not agree that forest and bush lands should be reserved to prevent erosion, as this alone stimulated and encouraged soil erosion because wild life removed the natural cover, the valuable grasslands. A good illustration of this was some of the South Island areas where the land had been denuded of its cover by deer, rabbits and goats as well as opossums.

Converting Forests

He said it was wrong for anybody to get the idea that bush lands should not be farmed. New Zealand was a young country and precautions should be taken to avoid throwing out of gear the natural agricultural working of the land. No other country had been able to proceed in converting its forest into grassland like New Zealand. “We are on the threshold of a new era of development, and I think we should be rather cautions in shutting up these lands at the slightest provocation,” said Mr Levy. “It has been proved that although burningoff is strongly discouraged by the State Forest authorities, no harm is done providing the grass cover holds and is not totally destroyed. “When the bush is removed it gives the grass foliage the chance to consolidate and we know that' so long .as hilly country is well grassed, it will never present soil erosion dangers. Our grasslands are our biggest assets, as we can increase production and utilise the land.” Preventing Erosion In dealing with'hilly country and gullies along with swift streams flowed, Mr Levy said that if these streams were left to meander at will, in time they would present certain soil erosion dangers, since the beds of the streams changed and widened, eating into the neighbouring hills, until major slips, slumping of the country and erosion finally set in.

To prevent this the stream had to be “streamlined” and the heavy fall eased or stopped to a certain degree. The correct method to arrest erosion of this nature was to plant trees and build debris dams, thus breaking the fall of the water, letting it down slowly and safely.

With the aid of lantern slides shown by Mr Sears, the speaker showed how the work was carried out both on large streams and the smaller type running along the beds of steep gullies. By planting trees such as willows, in making debris dams and arresting the fall of streams, results wer eobtained quickly and efficiently. Importance of Waterways “If we can prevent streams wandering and changing their course at will we will be able to stop certain erosion,” -said the speaker. “If we stop streams and rivers from widening, this also helps. This is where the debris dam comes in, and as you known assistance is being given in the form of subsidies for this kind of work carried out by farmers and others. “Tree planting is also receiving help in the form of subsidies and although there is not one yet for grassing lands we hope eventually to get assitance in this direction.”

Mr Levy regarded waterways as being of such importance that in the future they would get the same attention as did roads and main highways.