k , Desirable Stocking 
10 
DIAMETER CLASS (Inches) 
HARDWOOD AND _ 
CYPRESS TYPES 
\_, Desirable Stocking 
DIAMETER CLASS (Inches) 
Figure 27.—Comparison of actual with desirable stocking 
of sound trees, by diameter class and forest type, Florida, 
1949. 
condition even in well-managed forests, but the num- 
ber of trees 11.0 inches and larger (all species) 
should make up about 9 percent of the total number 
of trees 1.0 inch and larger.? In Florida, however, 
trees 11.0 inches and larger make up only 3.6 per- 
cent of the total in pine types and 4.9 percent in 
hardwood and cypress types. 
Perhaps even more significant than the present 
shortage of large timber is the trend in volume (fig. 
28). The number of trees 13.0 inches and larger 
decreased for all species throughout the State since 
the first forest survey. The number in the 10-inch 
class increased mainly because of the large ingrowth 
of young trees into this size class. The number of 
trees in the 12-inch class did not change much. At 
the time of the first survey the average volume per 
tree of all pine trees 9.0 inches and larger was 89 
board feet; in 1949 it was 77 board feet—a 13-per- 
cent decrease. The average volume of hardwood 
trees 13.0 inches and larger® was 126 board feet in 
1949—23 percent less than at the time of the first 
survey. 
°Based on stocking standards used by the Forest Survey. 
See appendix, p. 56. 
® Hardwood trees in the 12-inch class were not recorded 
as saw timber at the time of the first survey, so no compari- 
son of trees smaller than 13.0 inches is possible. 
Smaller timber means lower board-foot yields. 
Yield studies (27) show that the average annual — 
erowth per acre for a 30-year-old fully stocked slash 
pine stand 7 inches d.b.h. and over (site index 70) 
is 267 board feet (International Rule), compared to 
410 board feet for a 50-year-old stand. Thus, annual 
saw-tumber growth could be increased by merely 
letting the trees grow larger before cutting them. 
PINE 
DIAMETER CLASS (Inches) 
| J INCREASE DECREASE 
Figure 28.—Change in number of trees, by diameter class 
and species, Florida, 1934-36 to 1949. 
The board-foot difference arises mainly because such — 
a large part of small trees, when sawn into lumber, 
goes into sawdust, slabs, and edgings. In cubic feet, — 
in stands 2 inches d.b.h. and over, the average an-— 
nual growth of a 30-year-old stand exceeds that of 
a 50-year-old stand. 
Pine Types Decreasing, Hardwoods 
Increasing 
Between 1934—36 and 1949, the area of pine types 
decreased by 2.3 million acres, a 14-percent reduction 
(fig. 29). This was accompanied by a considerable 
increase in the number of hardwood saplings and — 
poles and in the number of cull hardwoods. 
A good deal of the decrease in pine types has 
taken place on the dry, sandy sites. Poor site quality 
32 Forest Resource Report No. 6, U. S. Department of Agriculture 
