72 CHARACTER AND COMPOSITION OF WOODS. 



spot can l)e stocked witli tlie species which is best iulapted 

 to the factors of the locaUty ; lience iiici"eased production 

 follows. 



{!).) Unless very extensive areas are availal>le, only mixed 

 woods enable the forester to meet the various demands of the 

 market. In the case of pure woods, and if a regular annual 

 yield of each of several species is expected, a complete series 

 of age gradations is required for each species, which, in the 

 case of a limited area, would lead" to small annual coupes. 

 For instance, if the intention is to grow five species on an 

 area of 500 acres under a rotation of 100 years, each cutting 

 w^ould extend, in the case of pure woods, over one acre, while 

 in the case of a mixed wood, the annual cutting may be live 

 acres in one block. 



It has already been stated, that only a few species are lit to 

 be grown in pure woods. At the same time many of the other 

 species yield a very superior quality of timber, or valuable 

 minor produce. All these would more or less disappear under 

 the system of pure woods, or at any rate they would not thrive 

 so well and would not develop equally line boles, as if grown 

 in mixed woods. Large sized timber of many light demanding 

 species can only be produced by mixing them with shade 

 bearing, and consequently soil preserving species. 



(r.) Many species suffer less from exteriuxl injurious in- 

 fluences, such as wind, fire, frost, snow, insects, fungi, if 

 raised in mixture with other more hardy species. — A shallow 

 rooted species had best be grown mixed with a deep rooted 

 species. — Conifers are less exposed to damage by fire or 

 snow, if mixed with broad-leaved species. — Insects are less 

 dangerous in mixed woods, as they generally attack only one 

 of several species ; moreover birds, the great insect destroyers, 

 are more numerous where broad- leaved trees grow, than in 

 pure coniferous woods. — Damage by fungi to conifers is also 

 considerably less if they are mixed with broad-leaved species. 

 — A hardy species mixed with a tender species protects it 

 against frost, drouglit and injurious air currents. 



