RECEXT TREXDS IX FOREST LAXD AXD TIMBER RESOURCES 



13 



represent the most widespread timber type group, 

 accounting for about 23 percent of all commercial 

 timberlands in 1970 (fig. 5). Much of this type 

 group now occurs on abandoned farm lands and in 

 mountain areas. Many stands include large pro- 

 portions of less desirable species such as post oak, 

 black oak, chestnut oak, and blackjack oak. 

 Some local types, however, are comprised of yel- 

 low-poplar and other desirable species. 



The oak-pine type, which covered 14 percent 

 of the eastern hardwood area in 1970, was mainly 

 concentrated in the South. This type largely 

 includes residual hardwoods left after cutting the 

 merchantable pine trees from mixed pine-hard- 

 wood forests. In the last few decades many 

 oak-pine stands have been converted to pine 

 stands by killing or cutting hardwoods, followed 

 in many cases by planting pines. 



Oak-gum-cypress forests include such valuable 

 species as sweetgum, cherrybark oak, tupelo, 

 and baldcypress, as well as poorer species. These 

 types occupied about 12 percent of the hardwood 

 forest area in the East in 1970. Nearly all of this 

 type occurs in the Mississippi Delta and other 

 southern river bottoms where sites are of high 

 productivity. 



Maple-beech-birch forests are found mainly 

 on upland sites in the Xew England, Middle 

 Atlantic, and Lake States regions. Elm-ash- 

 cottonwood types are largely concentrated in 

 bottomlands in the Central and Lake States 



Forest type groups in the United States, 1970 



EAST WEST 



80 100 



MILLION ACRES 



Figure 5 



regions. Aspen-birch types are found chiefly 

 in the Lake States region. This type is composed 

 of relatively short-lived pioneer species that 

 have taken over large areas following logging 

 and fires. 



Eastern softwood forests. — Southern pine type 

 groups made up a little more than 14 percent 

 of the Nation's commercial timberlands in 1970. 

 These types are concentrated on the Coastal 

 Plain and Piedmont extending from New Jersey 

 to Texas. In 1970 harvests of southern pine made 

 up more than one-fourth of the total timber 

 harvest in the United States. 



Spruce-fir and white-red-jack pine types in 

 the Lake States and Northeast covered about 

 6 percent of all commercial timberlands in 1970. 

 As in the case of southern pines, these forests 

 also support substantial local industries. 



Western forests. — In the West about 85 percent 

 of the commercial timberland supports softwood 

 types. Douglas-fir and ponderosa pine types 

 each make up about 6 percent of the total com- 

 mercial timberland in the United States, and 

 other western softwood type groups 9 percent. 

 Most Douglas-fir areas occur on the Pacific 

 Coast west of the Cascade Range where sites 

 generally are highly productive. Douglas-fir also 

 occurs in California and the Rocky Mountains, 

 frequently on moderatly productive sites and 

 mixed with other coniferous species. 



The ponderosa pine type occupies a large 

 act e age in eastern Oregon and Washington and 

 in 1970 was also the most extensive commercial 

 forest type in California and the Rocky 

 Mountains. 



Recent trends in forest types. — Shifts in land use 

 patterns and natural succession have caused many 

 important changes in forest type areas. Thus 

 bottomland haidwood forests were reduced about 

 20 percent between 1962 and 1970 by clearing of 

 forest land along the deltas of the Mississippi 

 River and its tributaries for farm crops. For many 

 years forests of the oak-gum-cypress group in this 

 area have supplied a major share of the Nation's 

 quality hardwood sawtimber. 



Many changes have also been apparent in areas 

 formerly supporting Douglas-fir. Red alder, other 

 hardwoods, or western hemlock have taken over 

 sizable areas after harvesting of the softwood 

 stands. Western hardwood types thus increased 

 almost 2 million acres between 1962 and 1970. 

 Industry may be able to increase utilization of 

 alder and other hardwoods, as in the case of aspen 

 in the Lake States, but at present most alder stands 

 offer little value compared to Douglas-fir. 



Forest Site Productivity 



Because of differences in such factors as soil 

 fertility, moisture, slope, aspect, and elevation, 

 there are considerable variations in timber-growing 



