RECENT TRENDS IN FOREST LAND AND TIMBER RESOURCES 



19 



timber volumes in the West, and the high propor- 

 tion of overmature timber in old-growth stands. 

 Much of the sawtimber lost included trees con- 

 taining large proportions of high-quality material. 

 But most mortality has occurred in inaccessible 

 and unroaded areas, especially on the National 

 Forests, where salvage has not been feasible. 



In many important softwood types, bark 

 beetles have been a major cause of mortality, 

 especially in old-growth stands of ponderosa 

 pine, Douglas-fir, and other western species. 

 The mountain pine beetle, for example, has 

 killed billions of board feet of lodgepole and 

 ponderosa pine sawtimber in recent years. Occa- 

 sional outbreaks of bark beetles in the South, 

 as in 1972, have also caused significant mortality. 



Foremost among diseases causing mortality 

 in forest trees are dwarf mistletoes, root rots, 

 white pine blister rust, fusiform rust, hypoxylon 

 canker, oak wilt, and dutch elm disease. 



So-called catastrophic losses from fire, insects, 

 or blowdown, included with other forms of mor- 

 tality in table 11, represent the most spectac- 

 ular losses, but on the average do not account 

 for a large part of total mortality and growth 

 losses. 



Additional Losses From Destructive Agents 



Destructive agents also cause additional losses 

 of timber by killing trees under 5 inches in diame- 

 ter, delaying regeneration by destroying seed 

 crops and seedlings, inhibiting diameter and 

 height growth, reducing quality and usable 

 inventory volumes through decay or other defects, 

 and inducing changes in stand composition from 

 preferred to less desirable species. 



The stunting of young trees by insects such as 

 shoot and tip moths, or by diseases such as dwarf 

 mistletoe, for example, frequently extends the 

 time required to grow trees to merchantable 

 size. Various defoliators such as the hemlock 

 looper and spruce budworm often lower forest 

 growth as well as kill trees. 



In other cases insects, diseases, or wind cause 

 deformities which limit usable yields of timber, 

 as in the case of white pine weevil in eastern 

 white pine stands. Crooking and forking of hard- 

 woods caused by insects or disease reduce usable 

 tree volumes. Tree borers cause significant degrade 

 and losses of value in some species and areas. 



Methods and data are not available to measure 

 these varied impacts of destructive agents, but 

 growth losses have been substantial and an im- 

 portant contributing cause of relatively low 

 current growth rates. Some causes of mortality 

 and growth losses, such as outright destruction 

 of trees by fires, blowdown, or flooding, are 

 highly visible and measurable. But reasons for 

 many losses are not obvious. Insects and diseases 

 also interact in diverse ways with each other 



and with other agents such as fire and man- 

 related activities. 



Salvage of Mortality 



An estimated 195 million cubic feet of dead 

 softwood timber and 57 million cubic feet of 

 dead hardwood timber was salvaged in 1970. This 

 was equivalent to about 7 percent of the total 

 estimated mortality of softwoods, and 3 percent of 

 hardwood mortality. Much of the timber salvaged 

 has been in concentrations of timber killed by 

 destructive agents, as in the case of timber blown 

 down in Mississippi by hurricane Camille in 1969, 

 and salvage operations following major fires. 



Efforts to reduce mortality include increased 

 thinning operations. Chemicals to control insects 

 and disease have also been widely used, but recent 

 opposition to the use of hard pesticides and delays 

 in control programs related to environmental 

 considerations are having adverse effects on the 

 effectiveness of control. New technology from 

 research programs, and increased forest accessibil- 

 ity through expanding road systems, are help- 

 ing reduce mortality and increase salvage 

 opportunities. 



TIMBER REMOVALS 



Timber volumes removed from growing stock 

 inventories on commercial timberland include: 

 (a) harvests of roundwood products such as saw 

 logs, veneer logs, and pulpwood; (b) logging res- 

 idues; and (c) other removals from changes in 

 land use such as clearing for agriculture or housing 

 developments, and withdrawal of forest lands for 

 parks or other nontimber uses. 



Total Timber Removals 



Timber removals in 1970 totaled about 14 bil- 

 lion cubic feet of growing stock, including 62.8 

 billion board feet of sawtimber (table 12). These 

 volumes were substantially above levels in the 

 1950's and early 1960's when removals averaged 

 about 12 billion cubic feet, including 50 billion 

 board feet of sawtimber. 



Softwoods made up some two-thirds of all grow- 

 ing stock removals, and three-quarters of all saw- 

 timber removals, in 1970. These removals were 

 concentrated in the Pacific Coast and South. 



About a third of all softwood removals in 1970 

 came from forest industry ownerships (Append. I, 

 table 21), nearly 40 percent from farm and mis- 

 cellaneous private ownerships, and about 30 per- 

 cent from public lands. 



Roundwood Timber Harvests 



By far the largest portion of timber removals 

 from growing stock consists of roundwood timber 

 products (fig. 9). In 1970, 87 percent of all soft- 

 wood removals, and 63 percent of all hardwood 

 removals, were used in this way. These products 



