168 BRITISH FOREST TREES 



which attains its maximum between the fortieth and eightieth 

 year, according to the quality of the soil, although the aver- 

 age annual increment does not culminate till between the 

 eightieth to the hundred and twentieth year (vide table on 

 page 45). Although pure beech forest on soils of average 

 quality yields over 8,000 cubic feet per acre, only 10 to 20 

 per cent, of this is usually first-class timber for technical 

 purposes, the rest being merely good fuel. 



When once the seedlings have passed through the stage dur- 

 ing which their cotyledons are apt to suffer from the fungoid 

 disease caused by Phytophthora omnivora^ the chief danger 

 to which the young crop is exposed is frost, and in localities 

 where late frosts in spring are frequent, the damage done is 

 often very appreciable throughout the thicket stage and even 

 later. So long as the natural soil-covering of dead foliage is 

 preserved from being blown about by wind, or being removed 

 for agricultural manure, pure forests of beech can easily on 

 average classes of soil attain an age of a hundred and twenty 

 years if desired in the interests of the proprietor. But if the 

 retention of this fall of foliage be not achieved, the forma- 

 tion of good humus is out of the question, and the protecting 

 and soil-improving qualities of the beech are squandered, as 

 the crop, which makes higher demands on the soil than 

 spruce l for example, or than most other trees, gradually 

 exhausts the soil in place of enriching and improving it. 



Pure forests of beech are reproduced naturally during 

 periods of twenty or thirty years, according as the fall of the 

 mature crop is desired between the eightieth to hundredth, 

 or between the ninetieth to hundred and twentieth year. 

 The process takes place by means of three fellings viz. : 

 preparatory, reproductive, and gradual final clearance, which 

 will be referred to more particularly when treating of natural 

 production. 



1 Vide page 30* 



