Bio-energy retains its mitigation potential under elevated CO2.
BACKGROUND
If biofuels are to be a viable substitute for fossil fuels, it is essential that they retain their potential to mitigate climate change under future atmospheric conditions. Elevated atmospheric CO2 concentration [CO2] stimulates plant biomass production; however, the beneficial effects of increased production may be offset by higher energy costs in crop management.


RESULTS
We maintained full size poplar short rotation coppice (SRC) systems under both current ambient and future elevated [CO2] (550 ppm) and estimated their net energy and greenhouse gas balance. We show that a poplar SRC system is energy efficient and produces more energy than required for coppice management. Even more, elevated [CO2] will increase the net energy production and greenhouse gas balance of a SRC system with 18%. Managing the trees in shorter rotation cycles (i.e., 2 year cycles instead of 3 year cycles) will further enhance the benefits from elevated [CO2] on both the net energy and greenhouse gas balance.


CONCLUSIONS
Adapting coppice management to the future atmospheric [CO2] is necessary to fully benefit from the climate mitigation potential of bio-energy systems. Further, a future increase in potential biomass production due to elevated [CO2] outweighs the increased production costs resulting in a northward extension of the area where SRC is greenhouse gas neutral. Currently, the main part of the European terrestrial carbon sink is found in forest biomass and attributed to harvesting less than the annual growth in wood. Because SRC is intensively managed, with a higher turnover in wood production than conventional forest, northward expansion of SRC is likely to erode the European terrestrial carbon sink.
Liberloo
Marion
M
Department of Biology, University of Antwerp (UA), Wilrijk, Belgium.
Luyssaert
Sebastiaan
S
Bellassen
Valentin
V
Njakou Djomo
Sylvestre
S
Lukac
Martin
M
Calfapietra
Carlo
C
Janssens
Ivan A
IA
Hoosbeek
Marcel R
MR
Viovy
Nicolas
N
Churkina
Galina
G
Scarascia-Mugnozza
Giuseppe
G
Ceulemans
Reinhart
R
D056804:Biofuels; D018533:Biomass; D002245:Carbon Dioxide; D004734:Energy Metabolism; D063245:Plant Development; D010944:Plants / Q000378:metabolism
D056804:Biofuels; D002245:Carbon Dioxide