AFFORESTATION IN THE UNITED KINGDOM 637 



{Alniis spp.), Poplars {Populiis spp.), Weymouth Pine {Pinus 

 Sfrobiis), Silver Fir (Abies pectinata), Spruce Fir {Picea excelsa), 

 Siberian Cedar (Punts Cenibra), Larch (Larix eitropced). 



Given a suitable soil, a number of these species may be 

 grown almost throughout the United Kingdom and the 

 w^armer the locality the less exacting they will be as to quality 

 of soil and quantity of light, although greater moisture of soil 

 and humidity of air will be necessary. The higher the tem- 

 perature the more rapid too will be their development at 

 first, both as regards height, girth and volume, but the reverse 

 is the case after the first few decades. Again, although the 

 toughness and flexibility of the timber will be greater, all the 

 other qualities will be best where the development is best 

 sustained. Thus it is seen how necessary it is to endeavour to 

 select the species to which the local conditions are best suited 

 and not to be deceived by the early growth of any species. 



As regards soil, the quantity, consistency and water capacity 

 are of first importance. Generally speaking the broad-leaved 

 trees are most exacting and the two or three needled pines least, 

 while intermediate between the two are Pinus Sirobus, Pimts 

 Ceiubra, Picea, Abies, Populus and Salix and Betula. 



It is evident from these considerations that conifers will 

 generally have to be selected for the purpose of afforesting the 

 poor and high-lying land, which is that chiefly available, and to 

 do so will be quite in keeping with the object of reducing the 

 dependence on foreign imports. 



The greatest security is to be found in establishing each 

 species where conditions indicate it as likely to give the best 

 results without impoverishing the soil, and not in the indis- 

 criminate mixture of a number of species which may thrive. 

 If this be the guiding principle, the variety of species cultivated 

 is still not unduly restricted and full account can be taken of 

 changes in the quality of the soil. The development of the 

 individual trees is better, as they generally have to contend with 

 their own species and not with others on which the conditions 

 may have diff'erent influences. In this way the land is utilised 

 to its fullest extent and, whilst the chief advantages of a mixed 

 crop are attained, the struggle for existence does not leave the 

 same doubt as to the composition of the final crop, nor does it 

 necessitate constant intervention as in the case of crops in 

 which there is an intimate mixture of diff'erent species. 



