THE INFLUENCE OF FORESTS ON CLIMATE.

Star (Christchurch), Issue 733, 28 September 1870, Page 2

THE INFLUENCE OF FORESTS ON CLIMATE.

The following paper on the above important subject, which is now attracting a considerable amount of attention in this part of the colony^ was read by Dr Schomburgk, Director of the Adelaide Botanical Gardens, at a recent meeting of the Adelaide Philosophical Society : — " Whether or not forests are of importance to climate is a question pretty freely ventilated of late bj science j but how important they are in the household of nature, and how closely connected with them is civilisation, I shall endeavour to prove in the course of this evening. " Several of my remarks were gathered out of a work of Professor Schacht, a German botanist, who, having distinguished himself by his works on botany, died in the prime of manhood, and too soon for science, which, lost in him one of its talented disciples. ! "Wherever we look we find the produce of the forest ; wherever we go we come in contact with it. Our dwellings, furniture, ships, railroads, tools, Ac. — our mind could not exist without it, nor could we protect ourselves from the cold of the winter, could not prepare our food, could not use the power of steam to fly across land and sea, if there were not or had not been forests. The climate, Bheltered situation, humidity, and fertility of soil depend on them. "In nature we behold a constant circulation of matter. The plants and trees absorb the carbonic acid generated by breathing or liberated by decomposition, and exhale instead oxygen, and this oxygen is necessary to the breathing of the living creation. "The green leaves and young branches of trees derive a great deal from the atmosphere by binding the carbon of the carbonic acid for the purpose of producing woody substance, amylon, fibre, Ac. Likewise the Boil gets the benefit by the dropping of the leaves, which decomposing, return to it partially the materials taken out of the ground by the roots. But, what is equally important, the leaves also cover the surface when decaying with a rich layer of humus, the shadows of the trees keep the ground moist, and so a constant decomposition takes place. " Now, we know that water is necessary for the existence of plants, for without water, no diffusion; without diffusion no vitality. If on one side the forests absorb a great deal of water out of the atmosphere, they also, on the other side, exhale humidity on a large scale. As a rule humidity surrounds them, rain falls, and dew. In the same manner as the lightning conductor attracts the electric fluid, the - forests attract and draw down the rain clouds, which benefit themselves, and likewise the neighbouring agricultural land. We find, therefore, as a consequence, always good agricultural land near forests. " Without doubt, you are all acquainted with the fact that plants are not alone nourished by their roots, but also nourished by their leaves, which are the lungs, and by their inhaling and exhaling purify the air in a great measure. It is perfectly well understood that dew is nothing else than a deposit of mist or vapour on the surface of the earth, which only can be generated by having been exhaled or evaporated from the surface of the earth : but the dry sand and naked rock cannot exhale any humidity, therefore dew very seldom falls on them, and only in consequence of attraction by a neighbouring forest. The forest itself presenting a very large surface for evaporation returns the loss of the soil in the shape of a refreshing dew, which falls on it in

abundance. If we find that very little dew falls on the soil of a very dense forest, the reason is, the rays of the sun cannot penetrate deep enough and convey heat thither, consequently very little evaporation can take place and produce radiation of heat. <r It is perfectly well-known that most of the rivers spring from wooded mountains. The forests conserve the water of a country, and thus nourish the rivers and springs. In a desert the rivers generally dry up. All those magnificent and powerful rivers of North America spring from primitive mountainous forests ; but I doubt that they will continue to discharge the same quantities of water in the sea for the future when their mother forests are gone. Already we hear that the Mississippi is perceptibly getting lower since the last decennium. We know also that when, during the winter, snow and ice are melting, great bodies of water suddenly gather in the mountains, and come rushing down with disastrous effects. But even here we perceive a great difference in the manner the waters are drained off. For instance, if such a stream springs from a dense forest, a great deal of ice, snow, and water are retained by the layer of humus acting like a sponge, and consequently the water is drained off gently and with much less danger. But when once the forests of a country are gone, there is nothing to check the wild impulse of the waters, and very destructive inundations take place. With reference to this, I wish to point out as one instance only the fearful inundation caused every year by the Rhone in France. " A mountain range, a wall, a forest, protects us againßt the winds, and we have no business to undervalue this protecting power of the forests, for it favours the growing up of young plantations, keeps the neighbouring agriculture in good condition, stops the progress of sand, keeps swamp fevers and ague away, and counteracts the drying effects of some winds, besides affording cooling shade. We note the astonishing fertility of tropical forests. Looking at this, I fancy nobody could reasonably doubt the beneficial influence of forests. "We have good reasons for presuming that a great many mountains at present naked and denuded of trees were formerly closely timbered. But when they were cut down the layer of humus left behind was protected no longer, the springs dried up, every violent rain washed some of the good land away, the soil became poor, and the vegetation died away. " A Government, or public body assuming the direction of a newly established colony, ought always to make the preservation of the forests a first consideration, and to establish protective laws, whereby the forestß could be preserved, and be made to yield a handsome revenue to the State at the same time. " Some countries, no doubt, at the present time, bearing the character of a hopeless desert, were always so — for instance, the Sahara; but other countries now in a similar plight were formerly in a different condition. All those vast and almost endless savannahs or plains, and prairies of Australand, South Asia, were once heavily timbered. Diodorus, of Sicily, at least mentions the existence of immense forests destroyed by fire. "According to C»sar and other Latin authors, G-ermany was covered with immense forests, and according to Herodotus and Thucydides the same was the case with Greece, Italy, Spain, Prance, and England. If we believe in the testimony of Diodorus, the forests of Spain were devastated to a large extent. We know that this country when subjugated by the Romans, was covered with large forests, especially its southern provinces. But at the present time only her coasts retain their forests, and the interior presents the aspect of a vast plain covered with heath, lavender, and rosemary. " The foreßts of the Peloponnesus were burnt down by Ali Pasha, and in consequence there came famine and drought. Likewise a Bussian general in modern time rendered his name in* famous for ever by burning and destroying wholesale the forests of the Caucasus for the purpose of routing out and starving the brave Tisherkessians. The name of this man is Dibitsh Balkansky. Since the destruction of

these forests the climate has changed entirely, the country has become barren, droughts and famine set in, and in consequence, thousands of these brave people emigrated to seek a new home in Turkey. "Prom Denmark, Sweden, and Bussia, Germany, North America, and, in fact, almost from every direction, we hear accounts how forests disappear, how fuel becomes dearer every year, and the re-establishment of forests becomes a question of a very grave aspect, and immediately connected with the welfare of a country. " A gentleman and scholar knowing Wb Homer and Horace by heart, and travelling through modern Greece, could never find out the meaning of the famous wine of Moreatis, for its vineyards a long time ago ceased to exist. He nowhere could behold the sacred pine grove of Poseidon. Where are now the pastures around the sacred castle of Dardanos, of which 3000 mares used to browse ? " Let us hope that the times are past for ever when the progress of civilisation was equal to wasting and desolating the surrounding nature. One thing is certain — a broad strip of waste land follows in the wake of culture, and noxious weeds like henbane, solanum, thistles, nettles, &c, serve to mark the footsteps of men. Before him nature in all her beauty, behind him desolation and hopeless waste. Looking at this picture, we have no cause at all to be proud of being called the lords of creation ; but let us hope that future generations will be wiser than the past ones. "If any one still feels inclined to doubt the influence of forests on the climate of a country, I beg to give several instances of modern times. Egypt, well known for its dry climate after the destruction of its forests, olive and other plantations, had about six rainy days every year on an average ; but since so many millions of useful treeß have again been planted, there are now about 24 rainy days per year recorded. " There is a man who deserves the greatest esteem from all civilised nations. Napoleon m., with all his faults, has given the world an example, which at least in Prance will render his name for ever immortal. Convinced of the great benefits the barren and swampy districts of France would derive if planted with trees, by his command many millions of trees have been planted in such districts of his empire. By his command thousands of acres of the desert in Algiers have been transformed into forests, with trees suitable to the climate, and with surprising results. The Government of Victoria provided him alone for this purpose with £cwt of seeds of the Acacia mollissin, 2cwt of Acacia lophanta, 201 bof gum, and 201 bof sheoak seed, and Messrs Law and Somner, seedsmen in Melbourne, with about 2cwt more of the above seeds. " By the last accounts, these plantations, especially of Australian species, have already reached the height of 9 to 12 feet, and with their rapid growth a great change of the climate is observable, and twice more rain and dew has fallen in the neighbourhood of these young forests than before. " By his command, more than 16 geographical square miles of the swampy and unhealthy country along the coast of the Bay of Biscay, in the department of Landes, where swamp fever was prevailing, have been planted with millions of trees, especially the cork-oak and swamp pine (Finus mariI tana), with a surprisingly beneficial result. Not alone that these trees have drained the land, but have changed it into a healthy country and fine forests. " Mr Chairman and gentlemen, I think there is not a more staunch advocate for the liberty of nations than I am, but I am also convinced that despotism is, in such respects, highly conducive to the welfare of a nation. " In Japan a law exists that whoever cuts down a tree is obliged to plant another instead. In Biscay every proprietor plants two for one which he cuts down, and the law compelling them is severely executed. Now, if I had the power, I would even go further, and would compel them to plant three instead of one or two. "By an ancient law of some nations, he forfeited his hand who cut down a tree without permission of the owner. "The motion of one of our legis-

latora — I think Mr "Wentzel — to lay out in every new hundred reserves for tree plantations, and the protection of such, is entitled to the thanks of the community; and I hope this motion will receive such support from the House as it deserves. " Our neighbours in Victoria, convinced of the necessity of such a measure for the well-being of the country, have already begun to carry out this scheme ; and in order to promote it in regard to forests, have not alone only called to life a Board of Porests, but have also appointed an inspector of forests, and under his direction the preservation of forest and young plantations will be secured. " Truly the desolation, the waste, and destruction of our forests have been so general that it now renders it imperatively necessary to take some effectual remedy against the repetition. It is more than probable that very little timber will be left, and the rising generation will feel this calamity, and cannot but occasion some uneasiness in the mind of those who wish well for their country. " In the early days of the colony, a great oversight has been made by the Government in not laying out in every hundred reserves containing, say about one or two square miles, for the purpose of forest plantations. In. omitting this, I consider it one of the greatest mistakes made. " I am sure some of you who have visited Prance and Germany must have been struck by the pleasing effect in seeing the railroads and public roads lined with ornamental and useful trees. It would be unreasonable to expect in our young colony this should already have been carried out ; but I may say the time has arrived when our earnest attention should be directed to the planting of trees in all suitable public places. " I am sorry to say our peculiar climate, especially the plains, is not very favourable for the growth of the noble forest trees of Europe and North America; but I am convinced there are a good many kinds of pines, especially the Californian ones, which grow most luxuriantly with us. There are a good many kinds of gum trees from Western Australia, as the famous jarrah or mahogany (Eucalyptus marginata) and the splendid red gum (Eucalyptus calophyna), whose luxuriant growth with us is undeniable, and their timber the most valuable in Australia. " Naturally the present generation would not derive a benefit from such a scheme ; we would only have the pleasure to watch their growth, and the pleasing sight of the green belts traversing our plains, denuded at present of all trees ; but lam sure the next generation would bless us for such an important undertaking."