156 THE FOREST LANDS OF NORTHERN RUSSIA. 
agricultural zone, the 60th parallel, or that of St. Peters- 
burg, marking generally the line of division between them, 
It is the former alone with which we are here concerned ; 
nor does the whole of it come under our cognisance. We 
have only to do with the forests in the Governments of 
Olonetz, Vologda, and Archangel, embracing the central 
and western portions of the zone. 
With the forests of the Governments of Olonetz, Vol- 
ogda, and Archangel, might be described the forests of the 
Governments of Viatka and Perm, but the exploitation of 
these, and more especially of the latter, is so affected by 
the demand for fuel used in connection with mining opera- 
tions in the Ural Mountains, that with perhaps equal pro- 
priety they might be brought under consideration in 
connection with those of Eastern Russia. From the men- 
tion of this it will be seen that it is not in ignorance of 
this fact that they are not brought under consideration 
here. : 
It has been frequently remarked that if we note as we 
ascend a lofty mountain range the vegetation through 
which we pass, there are successive zones of these, varying 
in the kinds of plants by which they are characterised. If 
from the base of some lofty range of mountains in a 
tropical land, which, notwithstanding the high temperature 
in the plain, have their summits covered with perpetual 
snow, we ascend to this cooler region, we shall find vegeta- 
tion of one kind giving place by degrees—tropical plants 
giving place to others, and these again to others, and such 
changes repeating themselves till at length we meet only 
with lichens and mosses and their allies. And like changes 
in the vegetation might be observed if we journeyed from 
the equator to either pole, representative of the successive 
zones on the mountain. Of this successive disappearance 
of different kinds of plants, as a mountain rises in altitude, 
Lapland supplies many illustrations, Baron von Buch 
writes :— 
‘It is extremely entertaining to climb great and rapidly 
