1 66 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



22. Sample Plot Investigations in Scotland. 



By H. M. Steven, Ph.D. 



One result of our lack of an established Forest Authority in 

 the past was that, compared with other countries, we knew 

 little regarding the volume production and other factors of 

 growth of our principal forest trees under different conditions. 

 Nevertheless a knowledge of the productivity of the forest 

 soils is the essential basis of a forest policy, just as a knowledge 

 of production is necessary in other industries. When data of 

 this kind were required by bodies or individuals considering 

 forestry, the only course was to use data collected on the 

 continent of Europe without any confidence, however, that 

 they were applicable to our island conditions. 



The carrying out of the Forest Statistical Survey in 1917-20, 

 when almost 500 sample plots were measured in Scotland, 

 provided data. This survey, which also traversed England, 

 Wales, and Ireland, enabled Yield-tables or Tables of Production 

 for different ages and qualities of locality to be made. Further, 

 the information collected made it possible to find out what were 

 the chief limiting factors to economic tree-growth in this country, 

 and how far they operated under different conditions. The 

 main results of this investigation were published by the Forestry 

 Commission, as Bulletin No. 3, on "The Rate of Growth of 

 Conifers in the British Isles." 



The results show that our island conditions are reflected in 

 the growth of trees, and that thus independent investigations 

 for this country are necessary. For example, in general, height- 

 growth is more rapid in early life here than on the Continent. 

 The more insular the climate the more apparent is this, it being 

 more marked in Ireland than in Great Britain. 



When some knowledge was obtained regarding production 

 under different conditions, it was considered that the next most 

 important subject of this kind for study was an investigation 

 into thinning methods for our chief species and conditions. 

 Although Scottish foresters are not without skill in this 

 important silvicultural operation, little has been done in the 

 way of a study of different thinning methods, carried out 

 systematically at regular intervals, especially in the light of 

 recent continental investigations. The importance ot such 



