20 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



those thickets is loose, and this means that the air can readily 

 penetrate to the roots. When the wood is thin the ground gets 

 hard and is covered with grass, bilberries, or heather; and you 

 know that a hard surface of the soil is not conducive to the happi- 

 ness of a tree. However, as the thickets of oak and Scots pine 

 get older and approach the pole stage, they thin out, and the 

 foliage no longer is dense enough to shade the ground completely. 



It is different with the beech and with other species that require 

 less light and can support shade. Whether in the stage of thicket, 

 of pole woods, or of mature trees, the ground remains shaded com- 

 pletely. Hence it is an advantage to have a lower story of beech 

 under a forest of oak or Scots pine. Nothing is more beautiful 

 than such a two-storied wood. The soil is being fertilised by the 

 leaves of the beech ; the standards of the oak or Scots pine grow 

 much more rapidly; they clear themselves of side branches; they 

 form long, straight, and regularly shaped boles, and their value as 

 timber is much greater than that from a pure oak or Scots pine 

 forest. 



And that applies not only to the oak or Scots pine, but equally 

 so to the larch, a tree which is justly regarded with much favour 

 in Scotland. Still, if you look at the larch forests of the Alps, 

 where it has its home, you will find that it grows best where it 

 has a lower story of beech, and sometimes a lower story of other 

 species. When the ground is covered by a lower story of a suit- 

 able species, the larch forms tall, clean stems, and it is much less 

 exposed to attack by fungus or insects. Foresters in Scotland 

 may find it useful to bear this in mind. 



As already stated, in Germany the tendency at present de- 

 cidedly is to encourage the growth of mixed forests ; and these 

 mixed forests, as I have said, as a rule consist of an upper story 

 of trees that require a great amount of light, like the oak or the 

 Scots pine, and a lower story, which in most cases is beech. But 

 you may say this is an utterly impracticable proceeding, because 

 beech can only be used as firewood, as a rule, and it fetches much 

 less than the wood of either the oak or the Scots pine. So it is, 

 and for the present I am content to leave you under the delusion 

 that the German plan of mixed forests is utterly impracticable. 



Let me now take you to that beautiful forest in Bavaria, which } 

 if any of you have ever time to visit, it will well repay the trouble 

 — the Spessart. It is situated in a large bend of the Main river, 

 one of the principal tributaries of the Rhine. The underlying 



