Rain acid buffer capacities of alpine forest soils in central Taiwan

The subtropical alpine forest ecosystem is vulnerable to acid rain deposited through the forest soils. Soil pH buffer capacity is a common index and plays an important role in buffering acidification. In this study, the pH buffer capacity of forest soils along an elevation sequence in central Taiwan was investigated and evaluated through conventional titration and mathematical calculation of proton affinity methods. High pH, cation exchangeable capacity, base saturation were observed in the low elevation site. Three phases of pH buffer capacity (pHBC) were proposed and well described the titration curve through linear fitting. The pHBCs showed no significant differences from the titration curves of various pedons and horizons. However, mathematical calculation of proton affinity potentials showed the highest correlation at the lower elevation site with soil pH (r = 0.90⁎⁎), cation exchangeable capacity (CEC) (r = 0.91⁎⁎), base saturation (r = 0.97⁎⁎), and X-ray non-crystalline sesquioxides (r = 0.68⁎⁎). It is important to evaluate the alpine forest soil pH buffer capacity by combining its proton consumption potentials.