BRITISH FOREST TREES 127 



forests are in reality very small oak woods prematurely 

 underplanted with silver fir ; an equally satisfactory and 

 perhaps safer method would be to form pure clumps of oak, 

 thin them out moderately in the pole-forest stage of growth, 

 and then underplant with silver fir. 



Silver fir forests with a fair percentage of oak and beech 

 often yield on good soils most satisfactory returns, as a high 

 percentage of the total outturn consists of timber of valu- 

 able dimensions both as regards length and girth. 



Self-sown birches are often to be found in blanks in forests 

 of silver fir, and are welcomed wherever there is a tendency 

 to rank growth of weeds, by suppressing which better oppor- 

 tunity is given for natural reproduction of the silver fir. On 

 average qualities of soil the fir is perfectly well able to 

 maintain itself under the moderate shade of the birch, 

 which, however, should be cut out at about thirty to forty 

 years of age, otherwise it interferes with and damages the 

 leading-shoots of the ruling species. 



Formation and Reproduction of Silver Fir Forests. Forests 

 of silver fir are treated in many respects similarly to beech 

 crops ; in pure forests they are mostly reproduced naturally 

 under the shade and shelter of parent standard trees. In 

 mixed growth of silver fir and spruce a similar method is 

 also adopted, but when light-loving species are underplanted, 

 planting up with small seedlings or transplants is generally 

 preferred to sowing. 



Natural reproduction is seldom so complete as to be 

 altogether independent of artificial assistance in the way of 

 sowing or planting. For the formation of woods in the 

 open, planting is adopted, as sowing leads to greater danger 

 from rank growth of grass ; in both cases, however, wherever 

 the shelter of standards is wanting, some quick-growing 

 temporary nurse is requisite in order to diminish the danger 

 from frost. It is only during the first year or two that seed- 



