Acid deposition and forest ecosystem sensitivity in Taiwan

On a basis of monitoring data, approximately 70% of the precipitation monitored in Taiwan is considered acid rain (exhibiting a pH lower than 5.6). I has been shown that acid deposition shows large spatial variation with northern Taiwan exhibiting the highest acid deposition in comparison with southeastern part. Dry deposition is least important in northern and northeastern Taiwan as these areas have the high annual precipitation with an even distribution. Dry deposition becomes proportionally more important in areas with low annual precipitation and high variability, such as southern Taiwan. Using RAINS-ASIA impact module the ecosystem sensitivity to acid deposition has been assessed and critical load of S to six forest ecosystems in Taiwan have been calculated. Results indicate that forest ecosystems in Taiwan are very sensitive to acid deposition due to their low soil pH (<5.5). Lowland subtropical forest ecosystems in Taiwan have low or moderate low critical load for S suggesting their sensitivity to acidity loading. The critical loads are exceeded for many forest ecosystems at present level of sulfur deposition that lead to hazardous consequences once the current buffering capacity will be depleted.