THE DOUGLAS FIR AS A COMMERCIAL TIMBER-TREE. 37 



Dr Nisbet shows in Our Woods afid Forests, page 208, that 

 the plantation had increased to 4850 cubic feet per acre; while 

 in 1903, or after only three years' growth, Dr Somerville in the 

 Transactions, Vol. XVII. page 273, calculates the contents 

 per acre to have reached the enormous total of 7977 cubic 

 feet. Either Dr Somerville's estimate would appear too 

 high or Dr Nisbet's too low, as, judging by the rate of 

 increment between the years 1888 and 1900, the three years 

 between 1900 and 1903 could hardly have been responsible 

 for an addition of 3127 cubic feet per acre. 



As a pit-wood tree the Douglas fir is well adapted, and is 

 deserving of consideration wherever crops cultivated for that 

 purpose are found to pay. Crowded together in pure plantation, 

 by the time they have reached their thirtieth year they will 

 be found capable of yielding an amount of pit-wood almost 

 incredible to those who have not seen the tree so grown. For 

 this purpose the planting should be done at not more than 

 3 feet apart, as otherwise a gross basal growth and a too 

 branching stem will certainly follow. 



While not a suitable tree for mixing with other species of even 

 age, the Douglas fir may with great advantage be introduced as 

 an under-crop in older oak and larch plantations. In this 

 respect it has no rival amongst conifers, taking into considera- 

 tion the value and volume of the timber it is capable of pro- 

 ducing under the shade of other trees. As the result of 

 experiments conducted on this estate, now of thirty years 

 standing, its superiority over spruce and silver fir has been 

 abundantly proved. Where both of those species have failed, 

 either as the result of attack by aphis or too dense shading, the 

 Douglas fir has grown into useful timber. In comparison with 

 beech as the shade-bearer, the latter probably is preferable, 

 owing to the greater amount of organic matter it is capable of 

 depositing on the ground, but as beech timber is of compara- 

 tively little value, better financial results may be anticipated 

 from the planting of the former. Excellent examples of the 

 beneficial results obtained by underplanting larch with both beech 

 and Douglas fir may here be seen, but no apparent advantage 

 has been gained by the use of the former over the latter. The 

 soil in both cases has been greatly improved, and the over- 

 head larches have increased in volume over the parts not so 

 treated to an almost incredible extent. 



