Trees and 'Pood from Acorns 



571 



without which there would be no 

 wildlife. 



LLOYD W. SWIFT is chief of the Divi- 

 sion of Wildlife Management in the 

 Forest Service. A graduate of the Uni- 



versity of California, he has been with 

 the Forest Service since 1929. He has 

 worked on range management and re- 

 search and wildlife management at 

 several field stations as well as in the 

 Washington office. 



TREES AND FOOD FROM ACORNS 



ALBERT A. DOWNS 



Acorns are more valuable than many 

 persons realize. From them, obviously 

 enough, come oak trees. From them 

 also (because they are rich in carbo- 

 hydrate, fat, and vitamins) come feed 

 for hogs, deer, turkeys, and squirrels, 

 and food for humans. 



Oaks produce good crops of acorns 

 once in 3 or 4 years, on an average 

 unlike the red maple and the birches, 

 which have good crops of seed almost 

 every year, and the longleaf pine, the 

 beech, and some other trees, which 

 yield seed only at long intervals. 



We do not know why yields vary 

 from year to year, but weather is prob- 

 ably an important factor. Late frosts 

 may kill flowers before fertilization and 

 even the fruit when it is in the young, 

 tender stage. Possibly oaks need more 

 than one growing season to build up 

 food reserves for a large crop of fruit; 

 oaks of the white oak group (white, 

 post, and chestnut oaks) ripen their 

 acorns in one season, but oaks of the 

 red oak group (northern red, scarlet, 

 and black oaks) need 2 years to ripen 

 their seed. 



The number of acorns produced by 

 different trees appears to depend only 

 on the size of the crown of the tree. 

 Because the size of the tree crown and 

 the diameter of the trunk are corre- 

 lated, diameter, which is easier to meas- 

 ure, is used as a guide to the productive 

 capacity of a tree. From a 7-year study 

 of five species of oak in northern Geor- 

 gia and western North Carolina, we 

 found that scarlet oak was the best 

 producer, and that acorn production 

 decreased in the larger diameters of 



the white oak and the northern red oak. 



The production of acorns varies not 

 only from year to year but from tree to 

 tree of the same sizes in the same year. 

 In 1942, a 27-inch scarlet oak produced 

 approximately 46,000 acorns; other 

 scarlet oaks nearby of the same size pro- 

 duced a fraction of that number. Very 

 likely some trees are good producers by 

 heredity, and some are poor producers. 



In most years, oaks, except the chest- 

 nut oak, produce more small aborted 

 acorns than well-developed ones. These 

 small, undeveloped seeds, often un- 

 recognizable as such, may be the result 

 of early insect damage or bad weather. 



It would seem that plenty of seed 

 would be available to reproduce oak 

 woodland. But that is not so. Only a 

 small percentage of the acorns ever 

 have the chance to germinate and 

 grow. Studies show that at the time of 

 seed fall 24 percent were damaged by 

 squirrels and birds and 30 percent by 

 insect larvae. Only 46 percent were 

 sound. In years of small crops, the pro- 

 portion damaged by insects, squirrels, 

 and birds is greater, and in years of 

 large crops it is less. On the ground, 

 insects destroy many more of the sound 

 seed, and deer, turkeys, squirrels, chip- 

 munks, and mice feed on them. 



In one place where deer were es- 

 pecially numerous one deer for about 

 30 acres the entire crop was eaten, 

 except in the heavy crop years. In an- 

 other area where the deer population 

 was estimated at one deer on 2,000 

 acres, many acorns were eaten, but a 

 fair surplus was left from good crops. 

 In general, when game is plentiful, few 



