CHAP, viii.] Formation of Timber Crops 167 



danger to the young crop from rank growth of weeds, and from 

 insect enemies (Melolontha and Curculionidae especially) ; whilst 

 it is also more difficult to recognize and to deal with the variations 

 in the quality of the soil with a view to making the best choice 

 of genera for mixed crops. Except on good land and with kinds 

 of trees hardy against frost, this method of treatment of the 

 crop should only be adopted, on soils below the average in 

 quality, when special considerations regarding either the land 

 or the kind of trees to be reproduced render inadvisable the 

 process of gradual clearance of the crop with simultaneous 

 regeneration under parent standards. Where the soil is shallow 

 or is apt to be easily heated, and to become deteriorated, as is 

 often the case when the percentage of lime contained is great, 

 the first point must be to maintain the land against the risk of 

 deterioration; hence the form of gradual clearance will be 

 advisable only to so small an extent as to consist merely in the 

 selection and utilization of mature trees, individually or in small 

 patches, without materially interrupting the density of the canopy. 

 Similar treatment will also be necessary in all localities exposed 

 to violent winds, or wherever the woodland covering is essential 

 for the maintenance of a good permanent supply of moisture 

 in the soil. Wherever sylviculture is practised on a consider- 

 able scale, coppice-woods are practically confined to mild 

 situations, and to shallow soils unsuited for the normal 

 development of the larger root-systems of trees when growing 

 in high forest. 



For the production of the more valuable assortments of timber, 

 growth in high forest is a necessity in the case of conifers. It 

 is also generally advisable with regard to broad-leaved genera, 

 although the composite form or copse, in which light-demanding 

 trees of various age-classes form the standards over a coppice- 

 growth of shade-bearing genera, is often highly remunerative 

 where any favourable market exists for the produce yielded by 

 the latter. 



The density of the crops is a factor which exerts no little 



