The Rhythm of Nature
iceBritain's Green Mantle. By A. G. Tansley. (Allen & Unwin. 18s.) Tuts is a book for the general reader as well as for the student of )Pant ecology. The latter will need to go further into the matter, nd to read the author's larger and more technical work, The British slands and their Vegetation, published ten years ago by the Cam- ridge University Press. The author's aim in the new work has been to avoid, as far as possible, technical detail, and to offer some 'general conclusions about the age and texture of what A. E. Housman called Britain's "overcoat." Those conclusions are not very ' encour- 4ing about what is happening today in the countryside. The author Sees there not a wise association of man's knowledge with the endencies of nature, but an obstinate endeavour to distort local Le htemperament of soil and climate by such processes as abnormal wheat production and the replacing of hard-wood forest by spruce. This .effort to make the English scene into something approximating to the Steppes of Russia or the Finnish lakcland woods is rightly to be deprecated. But these false practices, dictated by economic and itical troubles, must be only temporary, and in time a right armony will be restored. Let us hope so, at least, or otherwise Pte England that we have known, we of the older generations, will disappear. t Meanwhile, there is much to enjoy, and to enjoy with that depth f historical as well as natural appreciation which gives a firm root o our pleasure in the countryside, linking it up with the story of our pie during the past several thousands of years. Mr. Tansky's k is a great stimulant in this matter, for his first chapter deals with the green covering of Britain from the time of the beginning of the post-glacial period some ten thousand years ago. By the pollen-analysis of peat bogs some accuracy has been given to the picture. As recently as ten thousand years ago we were joined to the I 1
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mainland as a peninsula, with the Thames a tributary of the Rhine, running to join it across what is now the lower part of the North Sea. For two thousand years there was a dry, warm period (the Boreal) during which pine forests covered the land. Then came a change, with the general surface of the island sinking some hundred feet, and wet weather lasting for some further three thousand years, a condition which destroyed most of the pine forest and produced much bog and marshland, with abundance of moss. These great cycles of change continued, and we appear to be today in a transition period, between wet and dry, warm and cold. In Roman times it was possible to ripen grapes abundantly here, as we know from various place-names and other evidence.
What is most interesting is the author's detailed account of the cycles of plant-growth, by which the vegetable consciousness of nature (a permissible phrase!) accommodates itself with infinite patience to the geologic and other more dramatic disturbances (now including the activities of man), working always towards a normal condition suited to the basic temperament of the place and latitude. For example, it appears that in all favourable climates woodland is ultimately established, and this holds for the British climate, wherz in general the oak tends to be the final resident. Towards this the dry, chalky uplands arc gradually graded down by the accumulation of humus from heaths, then shrubs, then hazels, and so on, until the oak supervenes, while in marshland the aquatic life silts up, gives hold for sedges, then grasses, then willows, hazels and alders, until again the oak finds root. It is a wonderful process, with its rhythm of inevitability moving as surely as that of the stars over the sky. Here is a counter-harmony to that of the spheres, with just as much philosophic significance for the observer.
The absorbing detail of Mr. Tansley's book is largely contributory to this main theme. Rich enough in itself, it takes on a poetic value as the reader sees its trend. The book holds more, too, for man has played his part as interrupter of this filmic, this symphony of the soil.
And therein lies most of our history. RICHARD CHURCH.
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