CHAP, v.] Soil and Situation 99 



washed out of the soil, clays offer comparatively large supplies of 

 tree-food within a small space ; hence the crops have a greater 

 density of leaf-canopy at all stages of their development than 

 similar woods growing on sandy soils. Unless the subsoil be 

 permeable, however, there is a danger of such tracts becoming 

 marshy. Owing to their low conductivity of heat, woodland 

 growth on clayey soils seems backward in spring. In the 

 natural regeneration of mature crops a good deal of soil-pre- 

 paration is usually required on clays in order to assist in the 

 decomposition of the dead foliage, which often forms a thick 

 layer on the soil in consequence of the density of the canopy 

 overhead. Not only is more foliage thrown down, but this 

 also retards the formation of humus by keeping the soil at 

 a low temperature. On such soils natural regeneration is very 

 easy ; for the preliminary clearances stimulate to increased 

 production of seed, and the young seedling growth bears shade 

 better than on poorer sandy soils. The reproductive capacity 

 of copse and coppice is also greater on clays than on sands. 



Limy soils effervesce when tested with drops of nitric acid. 

 Marls and true limes are both comprised within this group ; 

 but in the former the limy constituent is equally admixed 

 throughout each particle of the soil, whilst in the latter it is 

 not. These also become by admixture sandy, loamy, clayey, 

 or stony limes or marls. Limy soils are apt to be wanting in 

 depth ; but with careful treatment they often show fine growth 

 of timber. Their consistency favours the equable distribution 

 of soil-moisture, even on steep hill-sides ; hence the root-system 

 easily attains normal development, and has few difficulties to 

 overcome in satisfying its requirements in the way of food- 

 supplies. But, when such soils have deteriorated through in- 

 solation following on bad management, the soil-moisture is not 

 retained ; the finer particles of earth get washed away rapidly ; 

 the soil rapidly becomes shallow, dry, and hot; and timber 

 production diminishes considerably. The re-wooding of dry, 

 limy hill-sides is one of the most difficult of sylvicultural tasks. 



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