Abstract
To quantify the impacts of forest vegetation on the acid buffering processes, hydrochemical observation data for two separate years were used to calculate the proton budgets in three small catchments, each consisting of the same granitic bedrock, but differing in vegetation development conditions. The increase in biological activity in the forested catchments, increased the net proton production by mineralization of organic matters and N transformation. In the forested catchments, the increase in transpiration reduced stream runoff. As a result, proton production by the dissociation of CO2 decreased. When the estimated value for the cation uptake by vegetation was included in the proton budget, forest development increased the sum of these net proton productions by 2.3 to 4.0 times that of bare catchments. However, more than 96% of these proton productions were consumed by weathering and cation exchange within the catchments. Also, it became apparent that the sum of these net proton productions by atmospheric input, N transformation, assimilation of cations, and dissociation of CO2 is strongly affected by the amount of annual precipitation and annual runoff. The fluctuation range of proton production due to the fluctuation of annual precipitation almost equals the range of the increase in proton production by forest growth.
