BRITISH FOREST TRKKS 221 



soils of a more swampy character, which will be referred to 

 in treating of the alder (vide page 230). 



Formation and Reproduction of Birchwoods can be easily 

 accomplished naturally wherever broken soil is in the vicinity 

 of trees over twenty-five to thirty years of age, for this species 

 usually produces a large quantity of seed annually, which, 

 being very light, is carried far and wide by the wind. 

 Wherever it seems desirable to form forests of birch for the 

 first time, sowing is usually adopted except on dry soils ; but 

 for the artificial introduction of birch as a subordinate into 

 mixed forests of other species, the preference is given to 

 planting as better enabling the number and position of the 

 plants to be fixed. 



Sowing. Fresh birch seed easily becomes heated, and 

 soon loses its germinative capacity, so that sowing should 

 be carried out early in autumn, especially on situations with 

 sandy soils, where the seed often ripens in August ; -seed 

 that has been dried, often lies for eighteen months in the 

 seed-bed before germinating. Some little preparation of the 

 soil is necessary, but this need only be confined to passing 

 over the soil with a coarse harrow, or bestowing on it any 

 similar treatment, to break up the surface of the ground and 

 expose the naked soil ; where any strong growth of weeds 

 makes this necessary by manual labour, the breaking up of 

 the ground is confined to bands or strips, and, after sowing, 

 the covering of the seed is amply provided for by passing 

 along the strips with light rakes or even with simple foot- 

 pressure. If sowing has been carried out soon after rain, 

 the seed adheres to the ground, and requires no further 

 attention. From 35 to 50 Ibs. of seed per acre are required, 

 according as broadcast sowing is confined to strips or carried 

 out over the whole area. 



Planting is generally carried out with seedlings of two to 

 live years, a preference being given in the older plants to 



