CORK OAK-——-RYAN AND COOKE 
At present, about 1,200,000 acorns 
are being collected yearly from ap- 
proximately 1,000 California trees. 
This permits planting for 400,000 trees 
per year. At this rate, it would re- 
quire 70 years to plant the forest. 
But, there are upward of 4,000 trees 
in California. Therefore, there is no 
reason why collecting cannot be or- 
ganized along progressive lines so that 
the entire acorn crop of over 4,000 
trees becomes available within a 
period of 20 years. 
A national forest could be started 
with a moderate beginning of 240,000 
trees the first year which would be 
increased progressively each year by 
a common difference of 80,000 trees. 
For example, 320,000 trees would be 
planted the second year, 400,000 in 
the third year, and so on, for 20 con- 
secutive years. At the end of 20 
years, 20,000,000 trees will have been 
planted. This will utilize the full 
acorn capacity of California’s old 
trees. Beginning with the twenty- 
first year, however, the first planting 
will have reached full fruiting matur- 
ity and its acorn crop can be added to 
that of California’s. Each succeeding 
year an additional larger planting will 
mature so that planting can be stepped 
up to the rate of 3,200,000 trees for the 
twenty-first year and 4,800,000 for the 
twenty-second year. At the end of 22 
consecutive years of progression plant- 
ing, 28,000,000 trees will have been 
planted, which is the number estimated 
to fulfill the country’s requirements. 
In such a progressively planted forest 
as that suggested above, its age at any 
time after the first year is composite 
and its cork yield is cumulative. 
Therefore, different methods had to 
be used to estimate the forest yield 
than those employed for the yield per 
acre when all trees were of the same 
age. After developing the proper 
mathematical procedure for deter- 
mining the yield of a progressively 
planted forest, studies were made on 
the basis of planting for 20, 22, and 
25 consecutive years. It was shown 
that the progressively planted forest 
8173693—49—_25 
373 
would not clear itself of first and 
second growths of cork and produce 
100 percent of the commercial grades 
of third and after strippings until the 
sixtieth year in the case of planting on 
the 20-year basis, and the seventieth 
year for the remaining plantings. 
It was also determined that on the 
20-year basis‘ of planting about 95 
years would be required for produc- 
tion to meet the country’s requirement 
of 160,000 tons annually. This is 
entirely too long a period to wait for 
our cork independence. On the other 
hand, the 25-year basis of planting 
will meet the 160,000 tons per annum 
requirement in the fifty-seventh year 
but, with reproduction at the rate of 
table 7, the yield of cork would be too 
great for its own commercial good. 
At the end of 100 years, the supply 
would be so far in excess of the demand 
that cork would inevitably become an 
economic “‘bauble.” 
The 22-year planting, with 28,000,000 
trees on 916,264 acres, presents itself 
as the most economical basis on which 
to build the Nation’s cork-forest in- 
dustry. The production rate of such 
a forest is presented in table 10 which 
shows that the country’s requirement 
TABLE 10.—Estimated rate of “‘stripped” pro- 
duction for the 22-year forest planted with 
28,000,000 trees on 916,264 acres in the positive 
potential cork area of the United States 
Yield in short tons per 
annum for stripping of— 
Age in years Third 
First Ss d re 
(virgin) econ aiter 
(com- 
mercial) 
AV ita srorcherencte D200 ree ie ee 
SOE ek ois cnore rs (053 SIOMAL tee 
AO eRe RII 25,065 | 11, 860 694 
LD Seca eore 18, 619 | 30,579 15, 316 
GOR vos etecesa aad | tueecee abel 24, 391 60. 391 
TO ert ce oer er eae or Rae esl een eae 116, 269 
SOR eat nraieta tees area ni ceta tere. = 165, 477 
DOs Re shot MR ASS, 89) SS 241, 710 
TOO sere tegey sass cepa le.d7M eid oaks 360, 367 
