344 
INJURY TO PRODUCTIVE POWER OF THE FOREST 
Another fact emphasized by one of our field party is the injury 
to other trees by a reduction in the density of stocking. Through this 
thinning-out process due to fires, the young trees that are left lose the 
benefit of competition with their neighbors. In restocking a forest the 
most desirable trees for timber are those which have a long, straight, 
well-pruned trunk and a short crown. Such trees are produced only by 
crowding when young and by the consequent struggle upwards for the 
light. Under present conditions there is no crowding during the sapling 
and pole stages so that the young trees branch close to the ground, with 
not enough side shade to kill off the side branches and thus to make good, 
clear lumber. 
This reduction of density in stands of mature timber is shown best 
by our stand tables (Nos. 1 and 2, pp. 313, 314) for average acres at Alto 
Pass and Jonesboro, where we have 43.65 trees per acre 6 inches and 
above in one case, and only 33.32 in the other owing to fires and culling. 
Normal yield-tables for hardwoods of similar age show that we should 
have 130 trees or more per acre in order that they may properly utilize 
the soil and prune each other sufficiently. Data following in tables 9 and 
10 obtained (a) near Ava, Illinois, in a tract which, according to state- 
ments of the owner, was 35 years old and had been burned over 8 years 
before, and (b) from an unburned New England stand will bring out 
more strongly this diminution in the number of trees and the consequent 
loss of volume-growth which results. 
Three quarter-acre plots were laid off in the Ava tract and the trees 
one inch and upwards in diameter were calipered. As can be seen in 
Table 9, the main species were white oak, black oak, and hickory, the 
percentages as follows: ares 
White oak’ Men Fo 25 eR ere 51.5% 
BlackiGalot), Saen. 2 ae ee ae ee 23.6% 
Ehickory Tick ec ee eee ee 15.3% 
1D) bia UR eerie acheter ie! Peed cess ote 6.0% 
Miscellameousmmet cre steer eat 3.6% 
A comparison with an unburned inferior second-growth hardwood 
stand in New England (Spaeth, ’20) thirty years old, is shown in Table 
10 just below our figures for one acre of Ava woods. The sites, if com- 
pared on the average heights of the dominant trees, can be said to be 
fairly analogous, 34.4 feet in New England as against our 30 feet. A 
comparison of the basal areas of each acre shows that our stand was 
decidedly understocked, 85.3 square feet in New England as against 60.2 
square feet for the Ava stand, this reduction in numbers resulting in a 
