Pe te tion WE Devin as ene ae E eae 
1886.] Causes of Forest Rotation, 851 
CAUSES OF FOREST ROTATION. 
BY JNO. T. CAMPBELL. 
(Continued from p. 527, June number.) 
ae my article on the above subject appeared in the June 
Naturauist, I have received a good number of letters, both 
from acquaintances and strangers, some making further inquiry 
about some phases of the subject, some offering explanations differ- 
ent from mine to account for forest rotation, and still others ridi- 
culing my theory that seeds, especially nuts, are carried by crows, 
wood-peckers and squirrels sufficient to plant such large districts 
of young forest trees as suddenly spring up where forests of a dif- 
ferent timber have been cut away, or such as have sprung up on 
the prairies of the Wabash river second bottoms since the white 
settlers have stopped the burning of the prairie grass. 
I lave been struck with the number of persons who seem to 
believe (as indicated by this correspondence) that when a forest is 
Swept away by the axe, fire or a blight, a different kind of forest 
Springs up spontaneously out of the soil. I admit’ that it has 
much that appearance. Especially does it appear to be so with 
weeds and grass, but the seeds of the latter are so small that it is 
about impossible to keep track of them; but forest trees that 
grow from nuts we may more easily observe, and if we find that 
their seeds have been carried far beyond their fall from the parent 
trees, and planted so as to produce trees, we may, I think, take 
the Planting of weed and grass seeds for granted. 
Dr. Clevenger, of Chicago, in a letter says, in speaking of the 
oak following pine in Minnesota, where the latter was cut off of 
the railroad sections: “ My idea was, that during hundreds of 
Years the chemical constituents of the soil having been drawn 
upon for the sustenance of pine, something near exhaustion had 
Scum ed, or at least enfeeblement of the ground, and that a seed 
which in its development required different soil constituents; or 
complementary ones, would be most apt to succeed the pine. 
The oak seems to be universally the terebinthinate follower in 
ae Scandinavia, Scotland, England, America and elsewhere. * * * 
sigh hundreds of miles along the Minnesota division of the North 
tacific railroad, the alternate sections of cleared and uncleared 
_ rest Presented, the year after clearing, a checker-board aspect of 
Pe oak and old pine. Then why should beeches and larches 
