Effect of aluminum on the growth and nutrition of tulip-poplar seedlings

Atmospheric deposition of nitrogen and sulfate is acidifying some ecosystem s, potentially increasing the availability of aluminum in the soil solution . The effects of Al on tulip-poplar (Liriodendron tulipifera L.) were inves tigated with seedlings grown in sand culture. Seedlings were exposed to Al at four concentrations ranging from 0 to 800 mu M. Reductions of 77% in sho ot biomass and 71% in root biomass were observed at 200 mu M Al. Aluminum r educed the concentrations of multivalent cations in leaves and roots. The C a concentration of leaves was reduced at 400 mu M Al, and the Mg concentrat ion of roots was significantly reduced at 200 mu M Al. Relationships betwee n tissue Ca, Mg, and Al indicated that Al alters the translocation of Ca an d Mg to the shoots and the accumulation of Mg in the roots. If mature trees respond in a similar fashion as seedlings noted here, then tulip-poplar ha s a low threshold for A1 toxicity, which may lead to declines in the health of tulip-poplar populations in ecosystems exposed to elevated levels of ac idic deposition.