946 



The Engelmann Spruce. 



[FEB., 



to its southern limits. Over the greater part of its range, it grows 

 in small bodies, and except in the south, where it is confined to 

 elevated localities, it is found in mixture with other species. 



Moisture, Light, and Soil Requirements. — The Engelmann spruce 

 is very dependent for its welfare upon proper moisture conditions of 

 both soil and air. Thus altitude and aspect are important factors, in 

 that they affect the amount of precipitation and its conservation. It 

 is very tolerant of shade. Young trees will endure 30-50 years of sup- 

 pression, and, when released, will recover rapidly and make good 

 growth. The physical condition of the soil, rather than its composi- 

 tion, is of the first importance, though it is believed that Engelmann 

 spruce yields its greatest volume on limestone soils. Swampy situa- 

 tions are good, unless the soil is sour, but in the seedling stage, growth 

 is sometimes slower in swampy places than on slopes. 



Habit, Root System, Growth, and Wood. — The crown of the Engel- 

 mann spruce is very heavy, thick and dense, and, except in very close 

 woods, extends well down the stem. Like other trees, Engelmann 

 spruce varies in form with the situation. As a rule, there is consider- 

 able taper, except in dense woods in the best situations. The most 

 cylindrical timber is to be found in deep, moist valleys, and on northern 

 slopes (when grown closely). In good situations the average size of 

 the Engelmann spruce varies from 80-100 ft. in height, and from 

 20-30 in. in diameter, though these dimensions are greatly exceeded in 

 individual trees — especially in Canada, 



Though the root system of the Engelmann spruce is superficial, it is 

 so well developed that the tree is wind-firm. As a rule mature trees 

 have several very strong lateral roots with a radius of 20 ft. or more, 

 which do not, however, extend more than 2 ft. below the surface of the 

 ground. This root system, while making the tree dependent upon 

 superficial soil moisture, enables it to thrive on shallow soils. 



Engelmann spruce grows rather slowly, except when light condi- 

 tions are favourable throughout its entire life — which is rarely the case 

 in its native forests, where it often takes 150 years and more to attain 

 a diameter of 18 in. 



The wood of this tree is very light in weight, pale yellow in colour, 

 very close, and usually straight grained, even-textured and easily 

 worked. Heartwood and sapwood are so nearly of the same colour 

 that it is difficult to distinguish between them. As a rule, heartwood 

 is not formed until after the age of 70 years. The wood is not durable 

 in contact with the soil, but finds many uses in protected places as 

 construction material. It is also used for pit props, sleepers, posts, and 

 poles of all kinds. 



Reproduction. — Engelmann spruce reproduces itself abundantly from 

 seed, provided that the surface of the soil is moist, and not covered 

 with dry leaves and needles to such an extent that the rootlet of the 

 germinating seed cannot reach the moist underlying soil. 



Management. — Owing to the nature of the habitat of Engelmann 

 spruce and to the characteristics of the species which grow in mixture 

 with it, the United States Forest Service recommends that forests of 

 this tree should be treated under the selection system, and be regarded 

 as protection forests. 



