SOME SUGGESTIONS AS TO THE PRINCIPLES OF THE 

 SCIENTIFIC NATURALISATION OF EXOTIC FOREST 



TREES. 



By C. C. Robertson, M.F. 



This subject is so much more difficult than that, say, of the 

 introduction of farm crops which mature in one or two seasons 

 and it has hitherto been so httle studied from a scientific point 

 of view in this or any other country, that I certainly do not claim 

 to be able to lay down any fixed laws. 



The practical importance of the subject to the unforested parts 

 of South A'rica is too obvious to require comment, but probably 

 it is of almost equal importance to our indigenous forests if they 

 are to be brought into a state of sufficiently rapid production 

 to allow of their economic management in the future. 



In the other branches of the science of Forestry, we can look 

 to some other countries, and particularly to Germany, for a 

 considerable knowledge of the fundamental principles, but the 

 scientific naturalisation of exotic trees has so far received com- 

 paratively I'ttle attention in these countries. It is, however, 

 true that during the last thirty years considerable importance 

 has been attached to the subject in Germany and definite ex- 

 periments have been carried on there. While it is claimed 

 that the credit of this is due to a nurseryman, John Booth, 

 who first persuaded the Forest Administration, through Bismarck, 

 to undertake the systematic introduction of exotics, the subject 

 in Ge many is now most closely connected with the name of Pro- 

 fessor Mayr, of Munchen, who has not only carried on experiments 

 with many of the important timber trees of America and Asia for 

 several years, but has also laid down some general principles. 

 Although some of his theories do not seem to have been based 

 on his own experience, nor to be supported by experience 

 elsewhere, they have at least been of great value in directing 

 scientific thought to the subject. 



In Great Britain, the introduction of exotics for forest purposes 

 has received some practical attention, but not much has been 

 added to the science of the question. The latter has been given 

 much more notice in America, where its foundation, namely the 

 ecological study of plant distribution, is perhaps receiving more 

 consideration than in any other country. 



In South Africa, most foresters have necessarily given thought 

 to the subject, and probably more experimental planting of 

 exotics has been carried out here than in any other part of the 

 Avorld, and it has yielded some results of great practical value. 

 L'nfortunately, however, much of it has been of comparatively 

 small value, owing to lack of central organisation and continuity 

 of direction, insufficient scientific method, incomplete records, 

 and unsuitable sylvicultural treatments. Moreover, over a 

 large part of the country, no planting at all was done until recent 



