RECENT TREXDS IN FOREST LAND AND TIMBER RESOURCES 



17 



softwood species. Roughly half of the softwood 

 growth was comprised of southern pines and 16 

 percent of Douglas-fir (Append. I, tables 23 and 

 24). 



The one-third of the total growth that was on 

 hardwoods included growth of both preferred 

 species such as select red and white oaks, sweet- 

 gum, yellow-poplar, and ash. walnut and cherry 

 (about two-fifths of total hardwood growth) and 

 species of more limited demand by industry such 

 as other oaks, hickory, beech, and cottonwood 

 (about three-fifths of total hardwood growth). 



Net Growth by Ownership 



Around 48 percent of the total net growth of 

 softwoods in 1970, and nearly three-fourths of 

 hardwood net growth, was on lands in farm and 

 miscellaneous private ownerships (Append. I, 

 table 21). Another quarter of the total net growth 

 of softwoods, and 12 percent of hardwood growth, 

 was on forest industry ownerships. The National 

 Forests and other public lands accounted for 

 about 28 percent of all softwood net growth, and 

 17 percent of hardwood growth. 



Net Growth and Potential Growth Per Acre 



Average net annual growth in 1970 varied 

 widely by section and by ownership from 23 to 

 65 cubic feet per acre (table 10). Net growth of 

 the sawtimber portion of total growing stock also 

 varied from an average of 77 board feet per acre 

 in the Xorth to 194 board feet on the Pacific Coast 

 (Append. I, tables 22 and 23). 



The relatively large average growth per acre in 

 1970 in the Pacific Coast section, in spite of the 

 presence of much old-growth timber, largely 



reflects a high proportion of land in high site 

 productivity classes and high rates of growth in 

 young stands on private lands logged over in the 

 past. In the South the presence of good sites and 

 much thrifty young growth resulting from pro- 

 tection and other forestry practices explain the 

 relatively high growth figures. 



Average net growth in the North reflected a 

 high proportion of land in lower productivity 

 classes, predominance of slow-growing hardwood 

 stands, and the presence of considerable rough and 

 rotten timber. Averages for the Rocky Mountains 

 reflected the presence of much old growth, frequent 

 stagnation of stands, relatively low sites, and 

 restocking problems following fire or logging. 



In spite of recent substantial increases, net 

 growth of timber is still much less than potential 

 yields in fully stocked natural stands (table 10 and 

 fig. 7). Even higher yields are attainable in stands 

 under intensive management with use of genet- 

 ically improved trees, fertilization, and spacing 

 control. 



The relatively limited net growth of growing 

 stock and sawtimber in 1970 in relation to poten- 

 tials in part reflected partial stocking of trees on 

 much of the forest area, mortality and growth 

 losses from destructive agents, and the presence 

 of brush and cull trees which limit regeneration and 

 increment of growing stock trees. These and other 

 factors such as restocking problems often make it 

 difficult and costly to achieve "full" stocking. 



In old-growth stands in the West, mortality 

 offsets much of the total growth and contributes 

 to the relatively low net annual growth per acre, 

 particularly on western National Forests. 



Table 10. — Average net annual and potential growth per acre, by owner, class and section, 1970 l 



[Cubic feet] 



Section 



All owners 



National 

 Forest 



Other public 



Forest 



industry 



Farm and 



miscellaneous 



private 



North: 



Current. .. ... 



31 

 68 



45 

 76 



24 

 60 



45 

 95 



38 

 66 



55 

 70 



23 

 65 



27 

 88 



33 

 59 



45 

 71 



23 

 54 



60 

 100 



40 

 72 



53 

 81 



47 

 70 



65 

 107 



29 



Potential 



69 



South: 



Current .. 



42 



Potential ._ .. 



75 



Rocky Mountains: 



Current . 



25 



Potential.. .. . 



50 



Pacific Coast: 



Current. .. .. 



58 



Potential . . 



96 







Total: 



Current 



38 

 74 



30 

 73 



39 

 68 



52 

 83 



36 



Potential.. 



72 







1 Potential growth is defined as the average net growth attainable in fully stocked natural stands. Higher growth 

 rates can be attained in intensively managed stands. 



