TKEES EOK WATER CATCHMENT AKEAS 135 



namely, the Sitka spruce, Picea sitchensis, and the white 

 spruce, Picea alba, both natives of North America. 



The common spruce is one of our most valuable trees, 

 but its cultivation in this country has seldom been properly 

 carried out. It has often been planted in unsuitable 

 mixtures upon low-lying land ; and when grown pure has 

 almost invariably been over-thinned. Its real use is to 

 produce a large volume of timber per acre in hilly or 

 mountainous districts, as it makes good growth at altitudes 

 where Scots pine and larch fail. In other words, spruce 

 is the main tree for the afforestation of the higher parts of 

 the hill pasture zone. Spruce is a superficially rooting 

 species, and grows upon the thinnest soil, provided there is 

 sufficient moisture available during the growing season. 

 At high elevations, where exposure to the wind and little 

 depth of soil are the chief obstacles to the growth of trees, 

 spruce will produce a considerable volume of timber. 



Spruce can be raised and planted out with great ease 

 and at a cheap rate, and it is a very hardy tree. It 

 endures much shade, and when grown in close order covers 

 the ground speedily, improves the soil by its layer of decay- 

 ing leaves, and in due time cleans its stem, and produces 

 timber of excellent quality. Used as a nurse for trees like 

 larch and pine, its branches persist indefinitely, and coarse 

 timber with large knots is the result. It should be planted 

 pure as a rule, though in some cases, as on cold clay soil, it 

 may be mixed with hornbeam or on dry soils with beech. 



As evidence of the considerable yield of spruce at high 

 elevations, some statistics are available in Journal of Board 

 of Agriculture, xvii. pp. 265 and 353 (1910), and Sup- 

 plement No. 9 (1912). A shelter belt on the summit 

 of Kerry Hill in Wales, fully exposed at 1525 feet eleva- 

 tion, the soil being four inches of peat on yellow loam, had 

 a volume of timber of 2880 to 3160 cubic feet (quarter- 

 girth measurement) per acre, corresponding to an annual 

 increment of 70 to 75 cubic feet per acre. At 1400 feet 

 elevation with less exposure, the soil being shallow loam, a 

 plot 43 years old had a volume of 3870 cubic feet 



