THE MANAGEMENT OF PLANTATIONS. 



41 



an area of any size, the species should vary with them. In 

 extensive forests the species is usually determined by the general 

 character of the soil, and differences of an acre or so in extent 

 are usually ignored. In the smaller woods and plantations of 

 this country, however, good forestry should recognise the nature 

 of every half-acre which differs from the rest, and select a species 

 adapted to it. This not only results in a healthier and more 

 profitable crop, but lends true variety to the plantation, and 

 is a very different style of mixing to that of planting so many 

 different species at regular distances apart. A plantation formed 

 on the former plan is thus made up of one or more (as the case 

 may be) groups of pure or unmixed wood, and each can be treated 

 according to the sylvicultural requirements of the species com- 

 posing it, and the group cut when mature without interfering 

 with other parts of the wood. It is scarcely necessary to 

 enumerate the respective species which are adapted to different 

 classes of soils, as those at all conversant with arboriculture will 

 have these things at their finger-ends. Soils, however, should 

 always be considered in relation to climate and rainfall, as the 

 latter exert quite as much influence upon the growth of trees as 

 the former, and it is only when both are favourable that the best 

 results can be obtained. 



A few words may now be said regarding 



Sylvicultural Mixtures 



and their advantages. To some extent the practice of mixing 

 different species of trees may be considered analogous to that of 

 growing farm crops in rotation. As the requirements of different 

 species with regard to plant-food vary, so the demand made upon 

 the soil for any particular ingredient of plant-food is less in the 

 case of a mixed than in that of a pure wood. This advantage 

 alone may be practically insignificant, but the composition of the 

 humus layer in a mixed wood is usually of a better character, 

 and this increases the temporary fertility of the soil. Insect and 

 fungoid pests are less troublesome, and cannot make such rapid 

 headway where individual trees of the affected species are 

 separated by those of another which enjoys complete immunity 

 from attack. A judicious mixture of light -demanders and shade- 

 bearers also enables a heavier crop of timber to be grown on the 

 same area, and thus increases the productive power of the soil. 



