EFFECT OF PH ON PHOTOSYNTHESIS OF 5 SPHAGNUM SPECIES IN MIRES IN OCHIISHI, NORTHERN JAPAN

In a laboratory experiment, the pH dependence of photosynthesis was in vestigated for five Sphagnum species: S. fuscum, S. magellanicum, S. g irgensohnii, S squarrosum and S. fallax, that are common in mires in O chiishi, northern Japan. The maximum photosynthetic rate of S. fuscum occurred at the lowest pH among the species. The photosynthetic rate o f S. girgensohnii, S. squarrosum and S. fallax varied little between p H 5.2 and pH 7.5, whereas the photosynthetic rate of S. fuscum and S, magellanicum tended to decline as pH increased. The results indicate t hat S. fuscum is most adapted to acidic conditions, while S. girgensoh nii, S. squarrosum and S. fallax are adapted to a wide pH range of amb ient waters.