largely determines how much of the 
demand is met by domestic sources. 
Because of their relatively low value 
per unit of weight and bulk, mineral 
materials used for construction are 
typically mined near where they are to 
be used. The Nation has sufficient 
supplies of mineral materials, although 
there are local areas where mineral 
materials used in construction, such as 
sand and gravel and rock aggregate, do 
not occur or occur only in limited 
amounts. 
Futures 
Background 
Projections of longrun demands and 
supplies are strongly influenced by 
prevailing shortrun conditions. The 
1980's have been a turbulent time as 
measured by fiscal and monetary 
policies around the world and other 
indicators of the macroeconomic 
situation. The basic assumptions for 
this Assessment, however, are 
consistent with historical conditions, 
and the assumptions are generally 
consistent with long-held national 
goals of continued economic growth 
and increasing income. The future may 
be different from that described in the 
basic assumptions. In recognition of 
this uncertainty, the Assessment 
analysis presents the results of five 
alternative futures. These futures differ 
from the Assessment projection in key 
assumptions about the future. The 
following descriptions highlight key 
points in each of the futures. 
The base Assessment projection is to 
be interpreted as the most likely given 
the associated explicit and implicit 
assumptions about variables that 
determine demand and supply. Key 
assumptions relate to management 
intensities on private lands, future 
outputs from national forests, and 
domestic and foreign demands for the 
various renewable resources. Projection 
results for other futures are compared 
with the base Assessment projections 
of consumption and other key measures 
of the renewable resource base. The 
five alternative futures are basically 
timber-oriented simply because data 
and analytic capabilities in other 
resource areas are not sufficiently 
advanced to differentiate meaningfully 
among alternative futures. 
Description of Futures 
Alternative future number | can be 
described as increased productivity 
of sawmill processing. It is the base 
Assessment projection modified by 
increasing lumber and product yields in 
the Pacific coast and Rocky Mountain 
regions so that they match changes 
projected for the South. 
Alternative future number 2 can be 
described as high exports of timber 
products. It is the base Assessment 
projection modified by increasing the 
projected exports of lumber, plywood, 
and pulpwood (including pulpwood 
and the pulpwood equivalent of pulp, 
paper, and board) by 20 percent in 
2000, 40 percent in 2010, 60 percent in 
2020, 80 percent in 2030, and 100 
percent in 2040. 
Alternative future number 3 can be 
described as reduced tree growth. It 
is the base Assessment projection 
modified by reducing the net annual 
growth on timberland in the North and 
South shown in the empirical yield 
tables used in developing the 
Assessment projections. Hardwood 
growth is adjusted downward 5 percent 
and softwood growth, 10 percent. 
Growth reductions already observed in 
local situations have generally been 
less than 10 percent (fig. 38). Except in 
isolated areas in California, growth 
reductions have not been a major 
phenomenon in the Rocky Mountain 
and Pacific coast regions. 
Alternative future number 4 can be 
described as surplus crop and 
pastureland (fig. 39). It is the base 
Assessment projection modified by 
assuming that all surplus crop and 
pastureland projected in the review 
draft of the Second Resources 
Conservation Act Appraisal (prepared 
by the USDA Soil Conservation 
