26 SOME PRACTICAL SUGGESTIONS. 



ance. Indeed, in many parts of the West Highlands of 

 Scotland it will be in practice the determining factor 

 when selecting ground for planting. Many areas of com- 

 paratively low and sheltered ground will be encountered 

 quite unfit for tree-growth on account of the inferior 

 quality of soil even after expensive preparation ; whereas 

 stretches of higher and more exposed ground of superior 

 soil quality in the same neighbourhood may safely be 

 planted. 



These conditions are due in the main to the absence or 

 presence of peat. Where peat is absent, provided there 

 be a reasonable depth of soil, altitude, shelter, and aspect 

 are the determining factors of suitability for tree-growth 

 of one kind or another according to the nature of the soil 

 and of the situation. Much land, however, which will 

 come under treatment will, in varying degree, be composed 

 of peat, or be what is commonly called peaty soil. As 

 regards pure peat, where it is less than eighteen inches 

 in depth the ground will normally, with more or less 

 treatment, be plantable. But the underlying soil or rock 

 must be taken into consideration. Areas will be found 

 where, with only a thin covering of peat, trees will not 

 grow ; but such exceptions are due in a greater degree 

 to the nature of the soil beneath the peat than would on 

 first sight be apparent. For the quality of the peat is 

 greatly influenced by the degree of imperviousness to 

 water of the soil on which it rests. Indeed, fairly steep 

 slopes will frequently be encountered with only six to twelve 

 inches of peat of very poor quality overlying boulder- 

 clay or some such retentive soil ; such slopes, although 

 having no appearance of undue moisture, are quite unfit 

 for tree-growth until thoroughly drained, and even then 

 are frequently inferior to peat several feet deep. The 

 same effect is not infrequently produced even with a non- 

 retentive soil, where a soil-pan has formed under the peat. 

 Until this pan is broken the area will be quite unplantable. 



