THE ACIDIFICATION CAPACITY OF WETLAND BRYOPHYTES AS INFLUENCED BY SIMULATED CLEAN AND POLLUTED RAIN

The acidification capacity of four wetland bryophyte species ((Scorpid ium scorpioides (Hedw.) Limpr., Sphagnum subnitens Russ. & Warnst., Sp hagnum squarrosum Crome and Sphagnum fallax (Klinggr.) Klinggr.) was s tudied in relation to the chemical composition of rain water. The effe cts of the species on the chemistry of throughfall water were investig ated experimentally in a 6 week experiment under treatments with simul ated clean rain and rain water polluted with (NH4)2SO4. Scorpidium sco rpioides increased the pH of throughfall water and growth rates were n ot affected by rainwater type. Sphagnum subnitens decreased the pH of throughfall water slightly in clean rain, but more so in polluted rain . Growth rates were not affected. Sphagnum squarrosum and Sphagnum fal lax considerably decreased the pH of throughfall water in clean rain a nd even more so in polluted rain. Growth rates were negatively affecte d by the latter type of rain. Sphagnum squarrosum and Sphagnum fallax are expected to have a substantially stronger effect on acidification of the ecosystem than Sphagnum subnitens, especially in areas with pol luted rain.