SOIL AND SURFACE CONDITIONS 129 



stracted from deeper layers by the roots. By these means 

 the washing out of the soil is resisted, but not altogether 

 prevented, as with every drop of water which filters 

 through into the subsoil, fertilising materials are abstracted 

 from the surface. 



' It is, therefore, not surprising that the soil is finally 

 impoverished. Many foresters believe that deterioration 

 of the forests on diluvial soils has taken place, and 

 probably with good reason. For hundreds and even 

 thousands of years the strife may be maintained against 

 the deteriorating factors, but they finally prevail, and 

 more easily when assisted by other circumstances. In this 

 way the heath has expanded at the expense of the broad- 

 leaved forests, and the soil changes that have perhaps 

 been impending for thousands of years occur in a few 

 hundreds, or in many cases in half a century. The 

 fundamental error of the view generally prevailing to-day 

 is that man alone, or almost entirely alone, has brought 

 about the present distribution of vegetation in the older 

 cultivated lands, and that nothing more is required to 

 restore the earlier and better conditions than to give 

 Nature her way again. Man can retard or hasten natural 

 processes, he can maintain his cultivated lands by 

 artificial methods, but his constant activity does not 

 prevail against the great march of Nature. The heath, 

 for instance, is a natural plant formation which would 

 not have been formed had not radical changes taken 

 place in the soil. Earlier or later, again, without the 

 agency of man, the peat or heath pushes back the forest. 



' The suppression of the forest by peat proceeds most 

 rapidly. Alterations in the surface, which consist 

 essentially of accunmlations of humus, proceed rapidly 

 as compared with changes in the mineral soil, and 

 opportunities for the origin and formation of peat are 

 numerous. In addition, the growth and extension of 



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