Table 2.2 — Land and water areas of the United States, by class of land and water, 1970, 1977, 



with projections to 2030 



(Million acres) 



Class 



1970 



1977 



Projections 





1990 



2000 



2010 



2020 



2030 



Land: 

 Forest and range land: 

 Forest land' 

 Rangeland^ 



754 

 819 



737 

 820 



732 

 808 



728 

 796 



724 

 785 



720 

 776 



718 

 764 



Total 



1,573 



1,557 



1,540 



1,524 



1,509 



1,496 



1,482 



Other land^ 



686 



697 



711 



724 



737 



749 



761 



Total 



2,259 



2,254 



2,251 



2,248 



2,246 



2,245 



2,243 



Water* 



102 



107 



110 



113 



115 



116 



118 



Total 



2,361 



2,361 



2,361 



2,361 



2,361 



2,361 



2,361 



'Land at least 10 percent stocked by forest trees of any size, or formerly fiaving 

 such cover, and not currently developed for nontimber use. Included in ttiese 

 lands are transition zones, such as areas between heavily forested and non- 

 forested lands and forest areas adjacent to urban and built-up lands, which may 

 not have timber production as a primary use. 



^Land on which the natural vegetation is predominantly grasses, grasslike 

 plants, forbs, or shrubs; and which is not currently developed for nonrange use. 



'Other land includes cropland, improved pasture, industrial and urban land, 

 and all other land categories except forest land and range land 



'Water area includes lakes and ponds over 2 acres in size, waterways, the Great 

 Lakes and coastal waters and estuaries excluding Alaska and Hawaii. 



For this Assessment, productivity of forest land is 

 defined as the amount of wood per acre per year that 

 can be produced in fully stocked natural stands. At 

 the present time, the Nation's forest lands as a whole 

 are capable of producing an average of 74 cubic feet 

 of wood per acre per year. But such averages obscure 

 some significant geographic differences. The two 

 eastern sections of the country, for example, have an 

 average productive potential of 65 and 77 cubic feet 

 per acre per year, while the forest land in the Pacific 

 Coast has an average annual productive potential of 

 97 cubic feet. 



Even within a single section, there is a wide range 

 of productivity. On the Pacific Coast, extensive areas 

 in the Douglas-fir ecosystem are capable of produc- 

 ing over 200 cubic feet of wood per acre per year, but 

 extensive areas of fir-spruce and pinyon-juniper can- 

 not produce 20 cubic feet of wood per acre per year 

 (tables 2.4 and 2.5). 



Rangeland productivity is measured by annual 

 production of herbage and browse per acre. Of the 

 various categories of rangelands, wet grasslands have 

 the highest inherent productivity, producing on the 

 average over 5,100 pounds (air-dry) of herbage and 

 browse per acre per year (table 2.6). The desert eco- 

 system produces practically no herbage and browse. 

 The desert shrub and desert grasslands ecosystems 

 are also low producers, averaging only 249 and 307 

 pounds, respectively. In general, grasslands have 

 higher average productivity than do the shrublands. 



Forest lands generally have a high potential for 

 production of herbage and browse if they have little 

 or only partial tree cover. For example, the redwood 

 forest ecosystem is capable of producing an average 

 of 4,800 pounds of herbage and browse per acre 

 annually; the hemlock-sitka spruce ecosystem could 

 average 4,200 pounds. Average potential production 

 for most other forest lands is in the range of 1,000- 

 2,000 pounds per acre. 



It is unlikely that major areas of forest land will be 

 cleared for use as rangeland, even though potential 

 productivity is high. Some forest lands, especially the 

 open-grown pine lands of the western United States, 

 now produce considerable forage for domestic live- 

 stock; and most forest lands produce herbage and 

 browse for deer and other wildlife. Forest stands can 

 be managed to increase the production or availability 

 of herbage and browse for livestock and wildlife, 

 while continuing the production of timber. However, 

 such management may lead to a reduction in timber 

 production. 



With the exception of southeast Alaska coastal 

 forests, the Alaska forest land and rangeland ecosys- 

 tems have generally lower productivity levels than 

 counterpart ecosystems in the other States. The 

 Hawaiian forest ecosystems have high inherent pro- 

 ductivities for herbage and browse, well over 4,000 

 pounds per acre. 



17 



