I5RITISII FORKST TREES 23 



larger individual trees. Where the distance between the 

 individual trees is greater than necessary, a tendency towards 

 development of the crown sets in at the expense of the 

 bole, stem, or shaft. Hence in order to obtain ultimately a 

 maximum of long, straight timber it is necessary not to allow 

 the canopy to be interrupted until the chief growth in 

 height has been attained. Experience also shows that 

 when, after completion of the total growth in height, 

 measures are taken to interrupt the canopy for the purpose 

 of allowing freer supplies of warmth, light, and air to become 

 available for the crown foliage, the increase of growth in 

 girth takes place with great rapidity, tending to the maxi- 

 mum possible yield obtainable. Growth in length is most 

 lively whilst the trees are still poles below two feet in 

 girth, but this varies according to species, situation, and 

 nature of the forest. The young crop, whether formed of 

 seedling growth spontaneously by natural regeneration or 

 artificially through sowingor planting, 01 of stool-shoots a.n&stoles 

 or suckers through coppicing, consists of saplings, and up till 

 the time that a forest in close canopy begins the natural 

 process of clearing itself of dead branches it is termed a 

 thicket ; from then till the boles have attained a girth of 

 about two feet at breast-height it is a pole-forest ; after that 

 it is a tree-forest, or high forest, or high timber forest. 



Whilst the outturn in timber usually forms the main 

 produce with a view to which sylviculture is carried on either 

 in high forest (e.g. oak, pine) or in coppice (e.g. osiers, 

 alders), yet the harvesting of the minor produce, like resin in 

 spruce or pines, and tanning bark in oaks and willows, can 

 under certain circumstances (e.g. oak coppice) be of greater 

 importance than the timber produced. 



For statistical purposes and actuarial calculations it is 

 important to distinguish between the outturn or final yield 

 of the crop and the preliminary or intermediate yield given 



