230 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY, 



5015 



obtained : — Averaere annual i)roduction of solid wood= - ^ =111 



cubic feet, exclusive of previous thinnings ; or, if only the time 

 since planting is taken into account : — Average annual production 



of solid wood= '-= 122 cubic feet. 



41 



If now we compare tlie average annual production of Douglas 

 fir and Scots pine, we find — Douglas fir =117 resp. 133, against 

 ►Scots pine = 111 resp. 122 cubic feet. Here, then, is an almost 

 inappreciable difference, especially if it is considered that the 

 quality of the soil in the Scots pine wood is decidedly inferior to 

 that of the soil in the Douglas fir wood. Unfortunately I had no 

 opportunity of measuring a larch wood in the vicinity of Taymount, 

 but it is well known to all foresters that, up to an age of forty-five 

 years, at any rate, larch produces a greater volume than Scots pine, 

 so that I may safely say : — " If grown in a well-stocked or crowded 

 wood and in localities of equal quality, Douglas fir is not likely 

 to produce more solid wood during the first thirty or forty years 

 than the larch, and probably also not more than Scots pine." 



The explanation is, that, although the individual Douglas fir 

 develops more rapidly in diameter and in height than a Scots pine 

 or larch, it requires, at any rate in Scotland, much more space ; 

 and consequently an acre of land will hold only a much smaller 

 number of trees. Moreover, I shall further on show that it is 

 more tapering than the important European conifers. 



On the other hand, the growing stock of a Douglas fir wood con- 

 sists of much larger trees (though smaller in number) than an 

 equally old larch or Scots pine wood, and this is a great advantage 

 where big timber fetches higher prices than moderate-sized timber. 

 This advantage will, however, to a considerable extent, disappear 

 with advancing age, when our indigenous timber trees reach the 

 size usually demanded in the market. 



Although the Taymount plantation gives some valuable informa- 

 tion respecting the early development of Douglas fir compared 

 with that of Scots pine, it leaves us as yet completely in the dark 

 as to the further progress of production with advancing age. We 

 have detailed and accurate information of the rate of increment of 

 various European conifers, such as Scots pine, spruce, and silver 

 fir, but our oldest pure })lantation of Douglas fir consists of trees 

 now only thirty-two years old. As regards the production per acre 

 in its native home nothing reliable is available. 



