BENEFITS AND RECOVERY OF ECOSYSTEMS
Policies to reduce emissions and deposition are ultimately aimed at decreasing negative effects and/or increasing recovery of affected ecosystems. The response of effects to decreases in emissions depends on the type of effect. Figure 6 shows relative response times to changes in emissions. The effect is fastest for air concentrations and the resulting improvement in visibility, the direct plant response, and acute human health. However, it takes longer for chronic health, aquatic systems, or plant responses to show the results of reduced emissions. It will take several years
to centuries before the forest ecosystem or soil nutrient status respond to the reductions. This difference in response times has to be taken into account when evaluating the changes in effect parameters, especially because the decrease in emissions started in the 1980s and 1990s.