THE DYNAMICS OF ROOT PRODUCTION AND LOSS IN BETULA-PAPYRIFERA SEEDLINGS IN RESPONSE TO ELEVATED CO2 AND AN ALUMINUM PULSE

Seedlings of Betula papyrifera were grown in sand/nutrient solution cu ltures in rhizotrone growth containers under elevated (700 ppm) or amb ient (375 ppm) atmospheric CO2 concentrations for approximately 10 wee ks. Thirty seven days after the begin of the experiment the plants wer e exposed to a 10 day pulse of 400 or 1200 mu M Al. Elevated atmospher ic CO2 increased both root production and loss. Exposure to Al reduced root production and slightly reduced root loss. The reduced root prod uction due to Al was amplified after the pulse had receded, resulting in a significantly lower net and gross root production at the end of t he experiment. There were no clear CO2 x Al interactions.