r.Krnsii FOREST TKKKS 71 



malpractices of seedsmen formerly in mixing the cheaper 

 spruce seed with that of the pine at a time when communi- 

 cations were not so good as they are now, and the errors 

 could not conveniently be rectified immediately. 



In what proportion the admixture of the spruce should 

 take place is mainly dependent on the nature of the soil 

 and situation. If the pine is towards the maturity of the 

 crop to be unmistakably the chief or ruling species, then 

 the spruce should not be introduced in greater quantity than 

 from one-sixth to one-fourth. Where past experience, how- 

 ever, has shown that the pine can easily be protected from 

 being overgrown and suppressed by the spruce about its 

 fiftieth year, the latter can be planted in equal quantity in 

 alternating squares or rows, in which case the spruce will 

 at first require most attention, whilst later on measures will 

 have to be taken to protect the pine against the other. 

 Where spruce forms only a small proportion of the stock 

 it is better to introduce it as individuals or in small patches 

 than to plant it out in rows. 



In mixed forests of pine and silver fir the latter is almost 

 always the ruling species, so that this mixture will be con- 

 sidered later on (vide page 125). 



In the Scottish highlands a mixture of birch with the 

 pine seems a most natural one. They are both species with 

 a considerable power of accommodation, and whose natural 

 habitat ranges from moors to sandy soils ; as the light 

 winged seed is easily wafted into the pine woods, birch is 

 very often found growing there. But in general the in- 

 troduction of birch into pine forests has not much to 

 recommend it, as it leads to interruption of the canopy and 

 insolation of the soil. Even on poor soils birch is the more 

 rapid in growth up till about the fifteenth to twentieth year, 

 when it is outstripped in height by the pine ; but until this 

 has taken place the leading shoots of the latter are liable to 



