MOISTURE FOREST

Evening Post, Volume CXII, Issue 48, 25 August 1931, Page 7

MOISTURE FOREST

HOW IT OPERATES

NO SINGLE PLANT IS WASTE

NIP HARM IN THE BUD

In moisture or "protection" forests (forests the main purpose of which is not timber utilisation but the regulating of water-flow) there are an increasing number of deer, and it is sometimes said that they do no harm because—in the early stages —only certain species of plants appear to be prejudicially affected. It is sometimes said also that a damaged protection forest regenerates sufficiently rapidly to control waterflow. In challenge of this line of thought, the New Zealand Forestry League writes as follows in the "New Zealand Magazine," quoting expert opinion to the effect that a protection forest, to do its w v ork properly, must exist in its entirety:— Prom all forestry standpoints, deer are the greatest enemy the New Zealand forest possesses. But to the protection forests in particular deer are an especial danger. In an address delivered before the Philosophical Institute of Canterbury, and reported in "Te Kura Ngahere" (journal of the Forestry Club of the Canterbury School of Forestry), Mr. F. E. Hutchinson, B.Sc.F., wrote that "if forestry is to become an important industry in New Zealand, and if the protection values of our mountain forests are to be developed to improve the condition of the valuable river-flat lands endangered by floods, and to hold the mountain slopes against erosion, then some systematic and thoroughgoing campaign against the deer is essential. That will not be done until the people of New Zealand are more thoroughly appreciative of the community values represented by these mountain forests, and of the menace to their -utility represented by the grazing animals, than is now the case." The fact that, as Mr. Hutchinson affirms, the public still needs educating in the community values of its own forests justifies the persevering propaganda of forest lovers. PROTECTION FOREST IS MORE VULNERABLE. The New Zealand native forest needs to be defended from browsing animals , because they endanger not only its protection value (its function of protecting the lower farm-lands) but also its timber value (its capacity to supply wood products). In New Zealand, however, the blow struck at protection forests by deer is even more vital than that struck at timber. Or, as Mr. Hutchinson put it, "the protection value is much more easily affected by grazing animals than is the utilisation value." When this forestry expert speaks of utilisation, he is referring primarily to timber production. Timber production is concerned about the timber trees, but to a Jess degree about the nonmerchantable species. These latter he sets aside with a question mark: "In our rimu forests we have two distinct forms of vegetation, an upper tier of ■ valuable conifers, together with under tiers of worthless herbaceous dicotyledons, palatable in the main to all classes of grazing animals. Whether the eating down of such growth (as by deer) is harmful, helpful, or of no significance cannot yet be stated, as wo do not yet know tho silvical relation of the rimu to its broadleafcd associates." Note that the word "worthless," and the doubt expressed in the succeeding sentence, are penned from the tim-ber-production angle. When you corno to tho protection forest angle, there is no doubt whatever about the valno of the non-timber trees. "Every species," writes this authority, "is of value." And he adds:— "The greater the density of plant occupation, and the greater the range of height tiers, the more effectively the unit will conserve moisture. Tall trees are necessary to make a deep band of air of high humidity, checking evaporation, and slow to respond to temperature changes, holding the snowfall. A flense under cover keeps out drying winds, and increases the non-conductiv-ity of the area. A dense ground cover prevents evaporation close to the soil, while a deep layer of moss, humus, etc., has a large storage capacity. This surface sponge breaks up surface runoff, while the lango root-systems of tho tall trees hold the top soil firm. No plant is unnecessary in such a combination, while any opening up of the stand by browsing of undergrowth, ground cover, surface mosses, etc., lowers the humidity and increases evaporation while the packing of the soil destroys its absorbent qualities, loading to sur.t.ace run-off, followed by gullyinrr slips, and sheet-erosion." Tho above is one of the most important and most detailed statements yet made in New Zealand by an established authority on the subject of what constitutes a fully-equipped protection forest. There have been some suggestions, from various quarters, that if protection forest is ravaged by deer or by fire, the succeeding regenerative growth will take up the task of regulating waterflow, and will "carry on" as though the forest had not been altered. To that idea, Mr. Hutehin:*m gives an emphatic negative, and with reasons. . DON'T WAIT TILL DAMAGE IS OBVIOUS. In carrying out the work of a protection forest, tall trees, smaller trees herbaceous plants, and lesser groundcover growths are all needed. Each *" »«qnirod. Every species has its use. The loss of not one of these (by Wsing or fire) can be a matter of from the protection forest pomt of view. So much is positive. It follows then, that tho moment when a protection forest comes to be ™™ l\ m * a 7 Ol, its coni P°nent S is the moment to bo alarmed. Investigation cannot be postponed until wholesale damage is obvious. Where an excess of browsing animals has damaged protection forest, it js well to correct tho excess and cive ameliorative regeneration a chance to make good, protected from pests. But it is better still to note tho first warning alterations, and, by immediately • correcting the excess of browsing animals, to prevent the greater damago arising. ■ If the public mind will grasp this distinction, it will rely less upon the unaided regenerative power of its protection forests, and will be more inclined to provide money to check tho browsing enemies in the earlier stages of their attack. To put the case concertedly, an informed opinion will not ■ wait until forests like those on the Tararuas have reached tho advanced stage of deterioration conspicuous in the Haurangi forest. The first necessity is to dispel the idea that any sort of a forest will do for a protection forest. A regenerating forest, even if it could be given the help of completo deer control, is not of equal value for protecting tho rest of the country. We must protect our protection forests as they are. Their liability to attack by wild animals, is the factor that is, on Air. HutI'hinson's authority, Ciiij.s-iiig more conown to foresters than iinv others.