34 FORESTRY 



subsoil in wet weather, while it stops the upward passage of 

 moisture in time of drought. 



If an impenetrable stratum of this kind be found at a depth 

 that will interfere with root formation, it must be broken. 

 Where the conditions permit, this may be effected by subsoil 

 stirring for work on a large scale, by means 

 of the steam plough, and for small areas by 

 picking (Fig. i) and trenching, so that the 

 soil is inverted. Owing to the great cost 

 of the operation, it is not usual to plough or trench 

 the whole ground, but to limit the work to strips 

 where the trees will be planted. If insufficiently 

 broken up, a fresh moor-pan is apt to form within a 

 few years, therefore the cultivation should be deep and 

 thorough enough to ensure complete disintegration. 



Localities in which sand-dunes occur require special 

 attention. Before shifting sand can be planted it must 

 be at least temporarily fixed. This may be done by 

 strewing Scots Pine branches over the ground, or sods 

 of a convenient size can be arranged to form a partial 

 covering over the unstable surface. The only suitable 

 species to plant on inland dunes are, besides the 

 common Scots Pine, Pinus Banksiana and Pinus rlglda. FIG j 

 For sea-coast sand-dunes Maritime Pine (Pinus maritima 

 or P. Pinaster) has proved of great value. 



Another work of reclamation is the treatment of ex- 

 cessive quantities of organic matter. These offer great 

 difficulties to afforestation. Peat mosses approaching a depth 

 of three feet cannot be successfully planted ; the difficulties 

 are too great and the expense of formation too high to be 

 at all in keeping with the returns. Where, upon turning 

 over the peat in simple digging, the mineral soil is met with, 

 planting may usually be carried out successfully. If, in an 

 old wood, leaf litter has accumulated, as it frequently does 

 in hollows, to an extent that would be harmful to the intro- 

 duction of a new crop, the excess must be disposed of before 

 commencing the regeneration work. 



