30 FORESTRY BRANCH BULLETIN NO. 33 



tained than in pine, for example, where the rapid growth becomes more and more 

 limited to the top of the tree near the short crown. Flaring of the butt is pro- 

 nounced, especially on large trees. The bark is moderately thin 0-3 inch to 0-5 inch, 

 reddish brown in colour and flaking off in soales 1 inch to 2 inches in diameter. The 

 root system has the heavy main roots radiating in an almost horizontal plane, especially 

 in wet soil, and forming a disk six to eight feet in diameter, and from them, 

 smaller anchor roots descend vertically. This makes the tree adapted to growth in 

 its favourite moist sites, where aeration in the deeper layers of soil is poor, but 

 renders it liable to windfall if left standing isolated or if fire burns off the anchor 

 roots, to do which only a light ground fire is required. On well drained soil the 

 tree is fairly wind-firm. The maximum size of spruce is in the neighbourhood of 

 36 inches in diameter at breast-height and 120 feet in height. Average sizes were 

 given in the stand tables. Spruce is the longest-lived tree of the region, except 

 Douglas fir. Four hundred years is about the maximum age. Thrifty growth is main- 

 tained up to from 150 to 175 years even in dense stands, but after that age there is 

 usually a decline to a slow rate of growth. 



Atmospheric conditions favourable to spruce include moist air, shade, and protec- 

 tion from the periodic, dry, hot winds. Although the region under consideration has 

 a rather dry climate, spruce is nevertheless able to grow under all conditions, and 

 the effect of climatic influences is shown only indirectly in the rate of growth where 

 its extent .is impossible to gauge, owing to the joint influence of other factors, such 

 as the character of the soil. The frequent frosts at the higher altitudes, even during 

 the growing season, have a very important influence in checking the -rate of growth 

 on the higher slopes. 



A moist, well-drained, deep soil is optimum. Thus the best developed spruce is 

 found in the valleys of small streams. On the broad river-flats, the spruce is gener- 

 ally small, owing either to poor drainage or to the soil being gravelly and therefore 

 raw. As slopes are ascended, and the soil becomes shallower and drier, the size of 

 the spruce becomes progressively less. 



In tolerance, spruce exceeds all its associates. The contrast with pine, with which 

 it is so often associated, is remarkable. The effect of its tolerance is to give the 

 tree a very deep crown, to enable it to maintain thrifty growth to a high age, even 

 in dense stands, since the crown does not tend to be reduced to a few branches after 

 the height-growth falls off. It also makes a very dense crown-cover, checking the 

 development of volunteer growth, and making the ground surface moist. On the 

 other hand, seedlings and young trees can persist and develop in older stands, 

 especially in stands with large proportions of pine; and although their growth at 

 times may be negligible (the result of too great shading) yet they are able to profit 

 at once by any increase in the amount of light reaching them. 



The chief damages to spruce are caused by fungi, wind and fire. Insect dam- 

 age appears to be rare. The attacks of fungi are limited. Only a small proportion 

 of the sawn lumber from spruce logs has to be culled for rot. Scattered trees can, 

 however, be found in any spruce stand, killed by fungus attacks. The susceptibility 

 of spruce to windfall was mentioned in describing its root-system. In case of fire, 

 spruce trees are very easily damaged, both on account of their thin bark and their 

 shallow roots. Spruce stands are, however, less subjected to destructive fires than 

 other types, due to the characteristically moist condition of the site. 



Reproduction. 



Seed Production. Spruce begins to produce seed at about thirty-five years of 

 age and bears heavy crops every three or four years. The cones are borne mainly 

 near the top of the crown and ripen in the summer. The seeds are shed in a short 

 period after ripening. The cones fall during the winter. The seeds are compara- 



