7© TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



optimum conditions for the growth of each species are by no 

 means the same. 



The mixture of larch and spruce has probably to some extent 

 been discouraged by the knowledge that these are the alternating 

 hosts of aphid pests of the Family Chermesidae. The wonderful 

 adaptability of these insects to any condition, however, makes 

 it immaterial whether the two hosts are planted in proximity or 

 not. As will be seen when the spruces are discussed, the mixing 

 of larch and Norway spruce is open to the objection that the 

 relative rates of height-growth are not the same in early life, 

 hence the spruces, in many cases, are suppressed. In the author's 

 opinion, there is a possibility that a larch-Sitka spruce mixture 

 might be successful. This should be a matter for experiment. 

 Of the other conifers, the author has seen a quite successful 

 larch-silver fir mixture, and this should also be a subject for 

 more extensive trials. Larch-Douglas fir is useless, owing to 

 the much more rapid growth of Douglas fir as compared with 

 larch. 



From a silvicultural point of view, the mixing with certain 

 hardwoods, such as beech and oak, would be more beneficial 

 than with conifers, owing to their superiority as humus-formers. 

 Some of the larch woods in Wales and in Ireland were planted 

 on oak-coppice areas. The few oak standards which have 

 come up with the larch have undoubtedly improved the soil 

 conditions. On areas suitable to beech, the mixing, say, 

 5-10 per cent, of this hardwood with the larch would certainly 

 help to maintain the soil fertility, and would probably increase 

 rather than decrease the volume production of the larch. 

 This should also be a matter for experiment. 



The successful mixing of larch with a shade-bearing species 

 by means of individual trees would solve many of the silvicul- 

 tural problems connected with the species. It is certainly a 

 subject for research and experiment. 



The mixing of larch with shade-bearers in blocks would avoid 

 many of the disadvantages of mixing by individual trees while 

 retaining a few of the advantages. Many of the areas suitable 

 for larch consist in part of spruce ground. The breaking up 

 of pure larch woods by belts of spruce would reduce the exposure 

 of the soil. Further, any existing groups of hardwoods, even 

 rowan, willows, and alder, should be left and encouraged. The 

 choice of species and the tending of the crop is more straight- 



