26 FORESTRY 



friable character is suitable for all species. Oak, Beech, 

 Silver Fir, Ash, and Elm are, in this matter of the soil's 

 mechanical state, decidedly exacting. Others are not so 

 much so, and will grow in spite of less favourable circum- 

 stances. This is especially true of the Scots Pine, which 

 on several kinds of soil and, indeed, where many species 

 could not live, such as poor sandy and peaty ground man- 

 ages to grow and even thrive. The predominance of the 

 Scots Pine in European forests is chiefly due to this power 

 of adaptability. The more that agriculture extended its 

 boundaries as was formerly the tendency the more did 

 the forest become limited to the poorer soils, where little 

 else but Scots Pine could grow. This result is also in part 

 attributable to the harmful effect of extracting the humus 

 (vegetable mould) from the forest and by past faulty manage- 

 ment in the tending of the woods. But though Scots Pine 

 is an adaptable species, it must not be thought that it is 

 suitable to plant everywhere. On the contrary, many soils 

 (clays and marls) grow the fastidious Oak better than the 

 Pine. 



The degree of depth of soil has its effect upon all species, 

 but many are able to accommodate themselves to situations 

 where the depth is deficient. Other conditions being favour- 

 able, Spruce and Beech will grow on shallow soils ; but Oak, 

 Ash, and Sweet Chestnut require considerable depth. 



The quantity of moisture in the soil has a very great in- 

 fluence in determining the species which will grow. Upon 

 very dry soils occur Scots Pine, Acacia, and Birch. The 

 wettest situations, where water is almost stagnant, can be 

 occupied by only common Alder and Birch (both Betula 

 verrucas a and pub esc ens}. 



As regards the demands made upon the mineral strength 

 and nourishing matter in the soil, the most exacting species 

 are respectively Elm, Sweet Chestnut, Ash, Oak, Sycamore, 

 and Silver Fir ; the least exacting, Birch and Scots Pine. 



Altitude is often the deciding agent for forest vegetation. 

 Along with it, however, the geographical position or latitude 



