Effects of long-term (10 years) exposure to elevated CO2 and O3 on trembling Aspen carbon and nitrogen metabolism at the aspen FACE (Free-Air Carbon Dioxide Enrichment) study site [Abstract]

This study was conducted at the Aspen Free-Air Carbon Dioxide Enrichment (FACE) experimental site, Rhinelander, WI, (USA). Since 1998, 12 experimental rings planted in 1997 underwent four different treatments: control; elevated CO2 (560 ppm); elevated O3 (1.5X ambient) and elevated CO2 (560 ppm) + O3 (1.5X ambient). In our study, foliage samples of Populus tremuloides Michx. were collected in the summer of 2006, 2007 and 2008 from each of three clones; namely, 216 (O3 tolerant), 271 (intermediately O3 tolerant) and 259 (O3 sensitive) growing within the aspen only sector of each ring.