18.3·World Reserves 377 r is the current rise in consumption per year in %(assuming ex- ponential growth).For example,if copper use increases by 8% per year,the consumption would double in 9 years.However,an increase in price and recycling may eventually slow down a too- rapid rise in consumption so that an exponential growth rate may not be encountered. Table 18.2 does not contain timber (a renewable material), which currently grows worldwide on about 3.4 x 109 hectares (27%of the land area)and whose 1995 world harvest was 1.4 X 109 m3.If used responsibly,and if substantial amounts of pulp are recycled(see below),the same amount of wood which has been harvested can probably be regrown.This would preserve the forests on all continents.However,between 1980 and 1990, the world lost an average of 9.95 X 106 hectares of net forest area annually,i.e.,roughly the size of South Korea.Most of the de- cline in forest area has occurred since 1950 and has been con- centrated in the tropical areas of developing countries to expand crop land,build cattle ranges,and extract timber.The temper- ate forests in industrial countries have essentially remained con- stant but consist largely of even-aged monoculture tree farms that do not support a high level of biodiversity as an ecologically com- plex natural forest does.Further,air pollution destroys large amounts of forests,particularly in Europe;specifically,26%of this continent's trees have moderate to severe defoliation.The world production of various forest products in different geo- graphic regions is listed in Table 18.3. The potential for fabricating polymeric materials depends largely on the availability of petroleum and coal.To illustrate Table 18.3 World wood production in 2000.Unit:106 m3,except wood pulp,which is given in 103 tons.Note:1 ton of sawn wood coniferous=1.82 m3;1 ton sawn wood broadleaved =1.43 m3;1 ton veneer sheets =1.33 m3;I ton plywood 1.54 m3;1 ton particle board 1.54m3. Sawn wood Sawn wood Veneer Particle Wood Country coniferous Broad-leaved sheets Plywood board pulp Africa 2.4 5.3 0.7 0.7 0.5 0.3 N.America 156.0 37.1 0.6 19.6 31.6 17.5 S.America 14.1 15.5 3.6 3.1 2.8 1.2 Asia 29.7 24.6 2.7 27.5 8.7 2.4 Europe 109.6 17.2 7.2 5.6 37.0 15.0 Oceania 6.5 1.7 0.4 0.7 1.2 1.2 Total 318.9 101.3 15.3 60.0 81.8 37.6 Source:2000 Industrial Commodities Statistics Yearbook,United Nations (2002). 1100n2.r is the current rise in consumption per year in % (assuming ex￾ponential growth).1 For example, if copper use increases by 8% per year, the consumption would double in 9 years. However, an increase in price and recycling may eventually slow down a too￾rapid rise in consumption so that an exponential growth rate may not be encountered. Table 18.2 does not contain timber (a renewable material), which currently grows worldwide on about 3.4 109 hectares (27% of the land area) and whose 1995 world harvest was 1.4 109 m3. If used responsibly, and if substantial amounts of pulp are recycled (see below), the same amount of wood which has been harvested can probably be regrown. This would preserve the forests on all continents. However, between 1980 and 1990, the world lost an average of 9.95 106 hectares of net forest area annually, i.e., roughly the size of South Korea. Most of the de￾cline in forest area has occurred since 1950 and has been con￾centrated in the tropical areas of developing countries to expand crop land, build cattle ranges, and extract timber. The temper￾ate forests in industrial countries have essentially remained con￾stant but consist largely of even-aged monoculture tree farms that do not support a high level of biodiversity as an ecologically com￾plex natural forest does. Further, air pollution destroys large amounts of forests, particularly in Europe; specifically, 26% of this continent’s trees have moderate to severe defoliation. The world production of various forest products in different geo￾graphic regions is listed in Table 18.3. The potential for fabricating polymeric materials depends largely on the availability of petroleum and coal. To illustrate 18.3 • World Reserves 377 1100 ln 2. Table 18.3 World wood production in 2000. Unit: 106 m3, except wood pulp, which is given in 103 tons. Note: 1 ton of sawn wood coniferous= 1.82 m3; 1 ton sawn wood broadleaved
1.43 m3; 1 ton veneer sheets = 1.33 m3; 1 ton plywood = 1.54 m3; 1 ton particle board
1.54 m3. Sawn wood Sawn wood Veneer Particle Wood Country coniferous Broad-leaved sheets Plywood board pulp Africa 2.4 5.3 0.7 0.7 0.5 0.3 N. America 156.0 37.1 0.6 19.6 31.6 17.5 S. America 14.1 15.5 3.6 3.1 2.8 1.2 Asia 29.7 24.6 2.7 27.5 8.7 2.4 Europe 109.6 17.2 7.2 5.6 37.0 15.0 Oceania 6.5 1.7 0.4 0.7 1.2 1.2 Total 318.9 101.3 15.3 60.0 81.8 37.6 Source: 2000 Industrial Commodities Statistics Yearbook, United Nations (2002)