Application of the simplified biogeochemical process (SIMPLB) model to determine the impact of acidic deposition on a Japanese cedar forest soil

The simplified biogeochemical process model (SIMPLB model) for determination of the impact of acidic deposition was applied to a Japanese cedar forest at Mt. Myougi in Gunma Pref. in central Japan. This dynamic model characterizes the biogeochemical processes of net nutrient cycling as the reduction ratio, K(RED), which is the ratio of the return by mineralization of litterfall to the root uptake of nutrients. The SIMPLB model estimates these biogeochemical processes from the nitrate concentration of the soil solution, without it being necessary to measure other biogeochemical parameters. About 1 year of observed data and values simulated by the model on the basis of soil data measured at the application site were compared to evaluate the SIMPLB model. The results showed that the SIMPLB model can use the yearly average K(RED) value for the long-term prediction of soil acidification. At the study site, the forest trees are about 38 years old, and the soil, an Andosol, is a black soil common in Japan. The SIMPLB model predicted soil chemistry changes until 2035 according to a deposition scenario.