4 Some Problems of Re-afforestation. 



mimimum and 284 cub. ft. as a maximum. To appreciate the 

 full significance of these figures we must compare them with 

 the yield of other conifers grown under average conditions. 

 Thus, Scots pine grown on average land will have done well 

 if, at fifty years, it shows a total growing stock per acre of 2,500 

 to 3,000 cub. ft. (true volume), the corresponding figures for 

 Norway spruce being 3,500 to 4,000 cub. ft. In the former 

 case the average annual increment is 55 cub. ft., and in the 

 latter 75 cub. ft., so that even the least productive of the 

 Douglas fir plantations has given three times as much yield as 

 an average Scots pine wood, while the best has produced more 

 than five times as much timber. 



It may confidently be asserted that no tree is capable of 

 furnishing such a high yield per acre as Douglas fir, and it 

 should therefore be extensively planted wherever the con- 

 ditions are at all favourable. 1 



Sitka Spruce. This is a tree whose native habitat is 

 confined to the bottoms of the valleys on the Pacific seaboard 

 of Canada and the United States. Introduced into Britain in 

 1831, it has been extensively planted, for the most part as 

 specimen trees, in many districts. At Durris in Aberdeenshire 

 it has proved superior to all other species at an altitude of 

 1,000 ft., and it has also given an excellent account of itself on 

 land too wet and too peaty to suit most trees. On hot, thin, 

 dry chalk in Sussex I find that the Sitka spruce is as promising 

 as any species, but the woods are too young to warrant a final 

 judgment as to its success under these trying conditions. 



There being no pure woods of Sitka spruce of any con- 

 siderable extent in this country it is impossible to quote 

 acreage volume figures, as in the case of the Douglas fir, but 

 both in height and in volume it surpasses the common spruce. 

 Mr. Crozier, who has had unusual opportunities for studying 

 the growth of the Sitka spruce in Scotland, states 2 that this tree 

 has grown at an altitude of 750 to 800 ft., in a mixed planta- 

 tion, so much faster than the common spruce that before the 

 seventeenth or eighteenth year the latter species had been 

 largely overgrown and suppressed. At this age the Sitka 

 spruces were 46 to 50 ft. in height, as compared with 35 ft. for 

 the tallest specimens of the common spruce. He gives it as 

 his opinion that Sitka spruce, in pure woods, and assuming 

 favourable conditions, should yield 6,000 cub. ft. per acre 

 of timber (quarter girth measure) at thirty-one years, and 

 10,000 ft. by the fifty-fifth year. Such yields compare not 

 unfavourably even with those of Douglas fir. In the same 



1 The green or Vancouver variety should alone be employed ; the grey or 

 Colorado variety is in all respects much inferior. 



9 Trans. Roy. Scot. Arb. Soo., Vol. xxiii., p. 12. 



