Average Wood Production in United States. 381 



inflammability of nonresinous wood, and to sprout reproduction. 

 In proportion to the cut-over land the Rocky Mountains show a 

 large percentage of land not restocking, while on the Pacific coast 

 climatic conditions make reseeding better and safer. The areas 

 of land not restocking are believed to be very conservative even 

 though the total seems startling when placed at about 82,000,000 

 acres of forest land or 90,000,000 acres of forest and woodland. 

 To the observant forester several trips through the Lake State 

 pineries and southern pineries (where one-half of this land is to be 

 found) are sufficiently convincing. This is the second large item 

 which must be withdrawn from the total so-called forest area. 

 The question may be raised whether this has not already been 

 excluded in the classification of total forest and woodland. It is 

 not, because it is inseparably mingled with the mature and grow- 

 ing timber areas, and it is still potential forest land but unable to 

 restock on account of recurring fires and lack of seed trees. For 

 example, Minnesota is given 15,000,000 acres of forest land, only 

 7,500,000 of which is restocking to a degree indicative of a second 

 crop. The other 7,500,000, while not entirely devoid of tree 

 growth, will require many decades of efficient fire protection and 

 a large amount of artificial regeneration to bring it into the pro- 

 ducing forest class. 



The growing forest area is got by deducting the mature forest 

 and the area not restocking from the total forest area. This is 

 approximately 225,000,000 acres of forest land, or 240,000,000 

 acres of forest and woodland. These figures give a total forest 

 area of about 495,000,000 acres, which is raised to 545,000,000 to 

 mclude woodlands (lands incapable of producing saw timber 

 forest). 



Having thus analyzed the total forest area and secured an ap- 

 proximation for the area of growing or producing forest, there 

 remains a discussion of the actual increment on this area. Since 

 (as has been stated before) the growing forest is made up of all 

 conditions of growth from the lightly culled mature forests pro- 

 ducing little increment to the pure dense stands of young growth 

 with an increment approaching the maximum, the arriving at an 

 average production is very difficult. The most important single 

 factor is the amount of growing stock present or the density. 

 The second is the age of the growing stock. 



In the first column of the table below, the annual production 



