The tree-lifter; or, a new method of transplanting forest trees by Greenwood George 1799-1875

Author:Greenwood, George, 1799-1875
Language: eng
Format: epub
Tags: Tree planting
Publisher: London: Longman, Brown, Green and Longmans
Published: 1844-03-25T05:00:00+00:00

PT. in. OR POISONED BY VEGETABLE GROWTH? 183

powdered rock. So that vegetation may be said to produce vegetation ; and we may possibly see in this general tendency to the increase of vegetable remains a main cause of the formation of bogs: and perhaps aqueous denudation may be a necessary agent to prevent the undue increase of vegetable remains over the whole surface of the earth.

And natural forests return to the soil all they take No necessity for

from it, and with interest: and Lvell should not talk rotation in

•^ natures

of trees dying out from the soil having * become ex- topping. hausted for trees,' or of the necessity of rotation in nature's cropping. Botation of crops is only necessary where man robs the soil of the produce he has raised, or raises plants by cultivation such as nature could not raise without cultivation. Plants in a state of nature stick to their appropriate stations^ so long as the physical conditions of those stations remain unaltered. The doctrine of rotation is in direct contradiction to the doctrine of fixed stations for plants.

It is perhaps "probable that were wheat sown every year on the same land, and ploughed in before ripening, the land would be enriched, not impoverished; that is, a great increase of carbonic acid would probably occur from vegetable chemistry, and a great increase of the inorganic constituents of plants from disintegration. In fact, although bearing wheat every year, the soil would become as rich as maiden soils always are. A process resembling this is w^hat does go on in natural forests, in addition to the absence of

denudation. In the case which Lyell mentions, of bogs formed 'by the fall of trees and the stagnation of water caused by their trunks and branches obstructing the free drainage of the atmospheric waters, and giving rise to a marsh,' and 'of mosses where the trees are all broken within two or three feet of the original surface, and where their trunks all lie in the same direction,' it is not the trees which are dying out on soils that have ' become exhausted for trees ' which break or blow over in wind: but, on the contrary, the trees which break or blow over in wind are the rank product of a soil which suits them, and which grows them too close to have side-boughs, and consequently too tall for their girthing and for their circumscribed roots. Many countries have ces^ed to be covered with forests from many different causes; but the last cause I should assign would be the soil becoming exhausted for trees. The formation of bogs by the over-luxuriance of woods may be one of these causes. I think it possible that, in some cases, the irruption of peat into woods from the bursting of bogs above them may have violently overthrown the trees ; in this case the trees should all lie down the stream: or that the drift from above, and quiet deposit of alluvial peat into

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