Increased nitrogen-use efficiency of a short-rotation poplar plantation in elevated CO(2) concentration.
We estimated nitrogen (N) use by trees of three poplar species exposed for 3 years to free air CO(2) enrichment (FACE) and determined whether the CO(2) treatment affected the future N availability of the plantation. Trees were harvested at the end of the first 3-year rotation and N concentration and content of woody tissues determined. Nitrogen uptake of fine roots and litter was measured throughout the first crop rotation. The results were related to previously published variations in soil N content during the same period. We estimated retranslocation from green leaves and processes determining N mobilization and immobilization, such as mineralization and nitrification, and N immobilization in litter and microbial biomass. In all species, elevated CO(2) concentration ([CO(2)]) significantly increased nitrogen-use efficiency (NUE; net primary productivity per unit of annual N uptake), decreased N concentration in most plant tissues, but did not significantly change cumulative N uptake by trees over the rotation. Total soil N was depleted more in elevated [CO(2)] than in ambient [CO(2)], although not significantly for all soil layers. The effect of elevated [CO(2)] was usually similar for all species, although differences among species were sometimes significant. During the first 3-year rotation, productivity of the plantation remained high in the elevated [CO(2)] treatment. However, we observed a potential reduction in N availability in response to elevated [CO(2)].
Calfapietra
Carlo
C
University of Tuscia, Department of Forest Environment and Resources (DISAFRI), Via S. Camillo De Lellis, I-01100 Viterbo, Italy. carlocaf@unitus.it
Angelis
Paolo de
Pd
Gielen
Birgit
B
Lukac
Martin
M
Moscatelli
Maria Cristina
MC
Avino
Giuseppina
G
Lagomarsino
Alessandra
A
Polle
Andrea
A
Ceulemans
Reinhart
R
Mugnozza
Giuseppe Scarascia
GS
Hoosbeek
Marcel R
MR
Cotrufo
Maria Francesca
MF
D002245:Carbon Dioxide / Q000378:metabolism*; D017753:Ecosystem; D007558:Italy; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D032107:Populus / Q000378:metabolism*; D012987:Soil / Q000032:analysis*
D012987:Soil; D002245:Carbon Dioxide; D009584:Nitrogen