Recent industrial timber studies link equilibrium ecological models to economic models to measure market impacts to potential climate change and include adaptation (Joyce et al., 1995; Perez-Garcia et al., 1997; Sohngen and Mendelsohn, 1998; McCarl et al., 2000; Sohngen et al., 2000). Conclusions from regional studies are similar to those in the SAR (Solomon et al., 1996) for temperate regions, suggesting that wood supply in these regions will not be reduced by climate change. Studies in the United States that consider only changes in forest growth find small negative or positive impacts on timber supply (Joyce et al., 1995; McCarl et al., 2000). Studies that consider growth effects and species redistribution effects (dieback of existing forests, followed by redistribution), as well as alternative economic scenarios, find that welfare economic impacts in U.S. timber markets could change by -1 to +11% (Sohngen and Mendelsohn, 1998). Generally, consumers are predicted to benefit from increased supply and lower prices. Producers in some regions of the United States may lose because of lower prices and dieback, although productivity gains could offset lower prices (Sohngen, 2001).
In contrast to the SAR (Solomon et al., 1996), more recent global market studies suggest that climate change is likely to increase global timber supply and enhance existing market trends toward rising market share in developing countries (Perez-Garcia et al., 1997; Sohngen et al., 2000). One study that uses TEM (Melillo et al., 1993) to predict growth changes finds that global timber growth rises, global timber supply increases, prices fall, and consumers and mill owners benefit (Perez-Garcia et al., 1997). Landowners in regions where increased timber growth does not offset lower prices perceive losses. A study using the BIOME3 model (Haxeltine and Prentice, 1996) suggests that producers in temperate and boreal forests could be susceptible to economic losses from short-term dieback effects and lower prices, although long-term (>50 years) supply from these regions is predicted to increase (Sohngen et al., 2000). Alternatively, studies that do not consider global market forces, timber prices, or adaptation predict that supply in boreal regions is likely to decline (Solomon and Leemans, 1997).
There is considerably less published literature available to assess the effects of climate change on nonmarket services from forests (Wall, 1998), including recreation and non-wood forest products. Climate change is likely to have direct effects on forest-based recreation. For example, lengthening of the summer season may increase forest recreation (Wall, 1998). Changes in the mean and variance in daily temperature and precipitation during peak seasons will affect specific activities differently, however. In the United States, some studies suggest that higher temperatures may negatively affect camping, hiking, and skiing but positively affect fishing (Loomis and Crespi, 1999; Mendelsohn and Markowski, 1999; Joyce et al., 2000).
Climate change also will have indirect effects on forest recreation. For example, changes in the structure and function of natural forests that are used for recreation could alter visitation patterns by causing users to substitute alternative sites. Alternatively, some recreational industries may have large adaptation costsfor example, snow-making costs in skiing areas may increase (Irland et al., 2001). In addition, institutional factors are likely to play a strong role in mediating the response of recreation because much of it occurs on public, natural forests where adaptation may be less economically feasible. Many forest-based activities, such as hunting, rely on management decisions by agencies that will have to adapt to climate change as well (Brotton and Wall, 1997).
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