Soil solution chemistry in forests with granite bedrock in Japan

Soil solutions were taken from three forest areas with granite bedrock in J apan (Abukuma, Tateyama and Hiroshima) to investigate pH values, forms of A l and the molar BC/Al ratios. In each area, 10 sites were chosen for study. At each site, a target tree was selected, and two soil solution samples we re taken from 10 cm depth at points 10 cm and 100 cm from the trunk of the tree to evaluate the effects of stemflow and throughfall on soil solution c hemistry. Values of pH of samples taken 10 cm from the trunks (referred to as S samples) and 100 cm from the trunks (referred to as T samples) ranged from 3.66 to 6.52 and from 4.55 to 6.48, respectively. For Japanese cedar ( Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa) trees, S samples showed lower pH than T samples, whereas the inverse relation was ob served for broadleaf trees. In the Abukuma and Tateyama areas, the concentr ations of monomeric Al (Al-m) were mostly below 30 mu mol L-1. In the Hiros hima area, however, extremely high Aim concentrations (up to 293 mu mol L-1 ) were observed at some sites. The molar ratio of BC (= Ca + Mg + K) to ino rganic monomeric Al was higher than 1 for all samples, except for an S samp le from the Hiroshima area having a ratio of 0.72.