1884.] FORESTAL NOTES. 191 



usual winter fallow, an autumn crop of rip grass to be dug iu 

 against spring. 



No one, I think, from a scientific point of view could oljject to this 

 treatment, wliich, chemically, not only returns to the soil all the 

 elements tliis crop has taken from it, but enriches it besides with 

 the organic matter the crop lias al)sorbed from the air ; while, 

 physically, the roots of the grass have not had time to bind the soil, 

 nor to dry it by intercepting the moisture before it can penetrate to 

 the subsoil. 



Such is not the case, it seems to me, with the grasses, brackens, 

 and heather that grow in woods. The sorts of weeds most abundant, 

 generally are so from having remarkably powerful binding and 

 searching roots, which take possession of the soil to the detriment of 

 their neighbours, whether these be plants, shrubs, or trees. Certainly, 

 if not carried off, they restore to the ground wliat they have taken 

 from it ; but I strongly suspect they continue using this humus for 

 their own exclusive benefit. We must remember that ' old sward ' 

 becomes excellent plant-food only when ploughed up, and its own 

 living organism destroyed. Like everything else, it must be dead 

 before it can be used for food. So, in woods, grass and shrub growth 

 become good humus after they have been killed hij the shade of the 

 leaf-canopy. 



But, as all know, the requirements of forest growth are even 

 much more physical than chemical. A sine qua nan for first-class 

 development is the free circulation of water in tlie soil and subsoil, 

 whence it is pumped by the roots of the trees, ascends into 

 their leaves, and is evaporated in the atmosphere. This circulation 

 of water is checked by the roots of grasses, which bind the soil aud 

 absorb its moisture. In a dry summer, if sward be dug up after 

 heavy rain, it is found that the moisture has not penetrated below 

 the surface, whereas loose soil absorbs it to a certain depth. The 

 drying and binding powers of heather are infinitely worse : when this 

 plant is continuous and well-rooted, one can hardly get a spade into 

 the soil. 



This consideration, weighty anywhere, may not be all-important in 

 damp climates like that of Scotland or Ireland, but iu even 

 moderately dry countries it is so, and continuous shade is in most 

 soils an absolute necessity for the healthy growth of timber. 



In the forest of Fontainebleau, wherever the Oak and the Beech 

 have been associated, both have in general done well, from the shade 

 fforded to the ground, and the beautiful humus deposited by the 

 Beech. But in some parts of the forest the Beech was allowed to 

 die out, and an attempt made to cultivate, instead of this mixture, 



