Forests offer multiple ecosystem services such as moderation of regional climate, mediating surface water flows, water purification, carbon sequestration, habitat for plants and animals, soil protection, repository for biodiversity, forest products (e.g., timber, fuel wood), and non-timber forest products (e.g., recreation). Some of these services are still not quantified and, moreover, they are often "bundled" with other services and hard to separate. In this section, I focus only on recent trends and the status of growing stocks and wood removal from forest, ignoring all the other services provided by forests.
Globally, there has been a slight decrease in total growing stock since 1990. As with forest area, tropical regions (Asia, Africa, and South America) have seen reductions in total growing stock, whereas Europe and North America have seen increases in total growing stock (Figure 2.11). This change has sometimes resulted from a change in area (described above) or a change in stocking density of forests. Trends in growing stock were not significant at the global level (not shown), although Europe (excluding Russia) had an increase in growing stock, while Asia had a decrease (because of Indonesia) (FAO 2005). Commercial growing stocks experienced a slight decrease at the global level, mainly because of a large decrease in Europe between 1990 and 2000. The other regions show small changes, with slight decreases in the tropics and increases in North America. Overall, Africa and South America had the largest amount of noncommercial forests (and they decreased over the last two decades), while North America had the least.
Data on wood removals show that Africa and Oceania are the only regions that saw an increase in wood removals since 1990 (Figure 2.12). The increase in Africa resulted from increases in both industrial roundwood and fuelwood, while in Oceania it was mainly due to an increase in industrial roundwood. The decrease in Asia was primarily a result of the logging ban in China (FAO 2005). Fuelwood was the primary cause of wood removal in Africa and contributed to roughly half the total wood removal in South America and Asia. In contrast, industrial roundwood production was the predominant cause of wood removal in the developed world.
Are these rates of wood removal sustainable? If forests are primarily managed for timber production, this question turns to one of whether sufficient time is allowed between harvests for the forest to recover. The ratio of growing stocks and wood removal rates yields an estimate of the number of years on average that a forest is allowed to recover (Table 2.4). The data shows that recovery times are shortest in Africa and North America, based on total growing stocks. Current rates of removal in these regions imply a ~100-year recovery time for forests, while in South America, forests require a ~300-year recovery time. The estimate based on total stocks, however, assumes that the valuable rainforests in the Amazon and Congo are potentially available for harvest. If we value the multiple regional and global ecosystem services provided by these forests, they must remain off-limits and we must restrict our analysis to commercial forests. On this basis, Africa and Oceania have the shortest recovery times (24 and 59 years, respectively), and Europe has the longest recovery time (90 years). Since forests can take 25-200 years to recover biomass fully,
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