224 ECONOMICS OF FORESTRY. 



ing areas small and so distributing them that they 

 are interrupted by old timber ; the same risk exists 

 with regard to insect damage, and the same plan — 

 disruption of the age classes — reduces that danger. 

 Again, older timber grown up in the close company 

 of a dense stand is wind-firm, and resists both wind- 

 falls (uprooting) and wind breakages (breaking of 

 stems), but when, by felling operations, portions 

 of the interior are opened up and exposed to the 

 force of winds, the trees are liable to be thrown, 

 especially if of shallow-rooted species, or on shal- 

 low soils. To avoid this damage it is desirable, 

 not only to make the felling areas narrow, so 

 that the wind has less force, but to locate the fell- 

 ings with regard to the prevailing winds (mostly 

 westerly), so that the older age classes lie in 

 the lee, the younger to the windward, the roof 

 of the forest or the felling series ideally rising 

 from west to east, the fellings progressing from 

 east to west. 



Where it becomes necessary to cut on the wind- 

 ward side, opening up timber unaccustomed to 

 wind exposure, a ivhid mantle is left on the wind- 

 ward side, which is also a commendable prescription 

 for small wood lots of farmers, to keep the drying 

 winds out. Or else, in due time, ten to twenty 

 years before the necessity for harvesting timber 

 so located, a severance felling is made, a small 

 opening which will induce the formation of a 

 wind-firm mantle. 



