Coppicing shifts CO2 stimulation of poplar productivity to above-ground pools: a synthesis of leaf to stand level results from the POP/EUROFACE experiment

Authors

  • Marion Liberloo,

    1. University of Antwerp, Research Group of Plant and Vegetation Ecology, Department of Biology, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium
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  • Martin Lukac,

    1. NERC Centre for Population Biology, Division of Biology, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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  • Carlo Calfapietra,

    1. University of Tuscia, DISAFRI, Via San Camillo De Lellis, I-01100 Viterbo, Italy
    2. National Research Council (CNR), Institute of Agro-Environmental & Forest Biology, Via Salaria km 29,300, 00015 Monterotondo Scalo (Roma), Italy
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  • Marcel R. Hoosbeek,

    1. Department of Environmental Sciences, Earth System Science – Climate Change group, Wageningen University, PO Box 47, 6700AA Wageningen, the Netherlands
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  • Birgit Gielen,

    1. University of Antwerp, Research Group of Plant and Vegetation Ecology, Department of Biology, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium
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  • Franco Miglietta,

    1. Institute of Biometeorology – National Research Council (IBIMET-CNR), Via Caproni 8, 50145 Firenze, Italy
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  • Giuseppe E. Scarascia-Mugnozza,

    1. University of Tuscia, DISAFRI, Via San Camillo De Lellis, I-01100 Viterbo, Italy
    2. National Research Council (CNR), Institute of Agro-Environmental & Forest Biology, Via Salaria km 29,300, 00015 Monterotondo Scalo (Roma), Italy
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  • Reinhart Ceulemans

    1. University of Antwerp, Research Group of Plant and Vegetation Ecology, Department of Biology, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium
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Author for correspondence:
Marion Liberloo
Tel: +32 3 820 22 79
Fax:+32 3 820 22 71
Email: marion.liberloo@ua.ac.be

Summary

A poplar short rotation coppice (SRC) grown for the production of bioenergy can combine carbon (C) storage with fossil fuel substitution. Here, we summarize the responses of a poplar (Populus) plantation to 6 yr of free air CO2 enrichment (POP/EUROFACE consisting of two rotation cycles). We show that a poplar plantation growing in nonlimiting light, nutrient and water conditions will significantly increase its productivity in elevated CO2 concentrations ([CO2]). Increased biomass yield resulted from an early growth enhancement and photosynthesis did not acclimate to elevated [CO2]. Sufficient nutrient availability, increased nitrogen use efficiency (NUE) and the large sink capacity of poplars contributed to the sustained increase in C uptake over 6 yr. Additional C taken up in high [CO2] was mainly invested into woody biomass pools. Coppicing increased yield by 66% and partly shifted the extra C uptake in elevated [CO2] to above-ground pools, as fine root biomass declined and its [CO2] stimulation disappeared. Mineral soil C increased equally in ambient and elevated [CO2] during the 6 yr experiment. However, elevated [CO2] increased the stabilization of C in the mineral soil. Increased productivity of a poplar SRC in elevated [CO2] may allow shorter rotation cycles, enhancing the viability of SRC for biofuel production.

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