I 4 BRITISH FOREST TREES 



Broad-leaved species. 



(A) Hardwoods 



1. Ash (Fr ax inns excelsior, L. ). 



2. Maple or Norway maple (Acer plala>ioidcs, L.). 



3. Sycamore or great maple (Acer fscudoplatanns, L. ). 



4. Elms, viz.: 



Common, English, or small -leaved elm (Ulmus cainpcstris, 



Sm.). 

 Scots wych, or mountain elm (Ultnus montana, Sm.). 



5. Hornbeam (Carpimis bettdus}. 



6. Sweet or Spanish chestnut (Castanea vesca, Gaert. ). 



7. Mountain ash, Rowan, or Fowler's service tree (Sorbus au- 



cuparia, L. ). 



(B) Softwoods 



1. White alder (Alnus incana, Willd.). 



2. Lime (Tilia parvifolia and grandifolia, Ehrh.). 



3. Horse-chestnut (dZscnlus hippocastanum, L.). 



4. Aspen (Populns tremitla, L.), and other poplars (Popitl-us 



species}. 



5. Willows (Salix species). 



(C) Smaller trees y and sh nibs in coppice. 



FOREST GROWTH IN RELATION TO SOIL. 



During growth, trees exact certain supplies of nutri- 

 ment from the soil, which would be restored to it if they 

 were left to fall as they grow. If, however, the timber be 

 utilised, with the removal of each crop the soil is left poorer 

 than before, unless the influence of the agents active in 

 decomposing the mineral and organic constituents of the soil 

 has been protected, for if these chemical changes be not 

 called into action the soil must gradually become exhausted 

 and deteriorate. In agriculture the larger supplies of nutri- 

 ment extracted from the soil are returned in the shape of 

 manure, which not only helps to restore the deficit, but also 

 stimulates to nitrification and decomposition of the soil ; in 

 sylviculture the only recompense that can practically be 



