Fig. 14. Showing the habit of black spruce where it invades the deep 
sphagnum-shrub cover of the bog. The central figure is a black spruce 
colony. White strips were tied to two branches which by striking root in 
the sphagnum have become independent though not yet detached young 
trees. 
Fig. 15. Dissection of a black spruce colony to show suppression of 
heath shrubs and sphagnum by shading and smothering. The depression 
in the bog surface is conspicuous but the shade was too dense to permit 
this photograph to show it. 
