| Autor: |
Millard, Peter, Sommerkorn, Martin, Grelet, Gwen-Aëlle |
| Předmět: |
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| Zdroj: |
New Phytologist; Jul2007, Vol. 175 Issue 1, p11-28, 18p, 2 Diagrams, 2 Charts |
| Abstrakt: |
Contents Summary 11 I. Introduction 12 II. The biochemical scale: the paradox of Rubisco 13 III. The ecophysiological scale: the profligate use of carbon 16 IV. The ecosystem scale: how forests respond to environmental change 21 V. Conclusions 23 Acknowledgements 23 References 23 As C3 photosynthesis is not yet CO2-saturated, forests offer the possibility of enhanced growth and carbon (C) sequestration with rising atmospheric CO2. However, at an ecosystem scale, increased photosynthetic rates are not always translated into faster tree growth, and in free air carbon enrichment (FACE) experiments with trees, the stimulation in above-ground growth often declines with time. So is tree growth C-limited? The evidence is reviewed here at three different scales. First, at the biochemical scale, the role of Rubisco is discussed by considering its evolution and role as a nitrogen (N) storage protein. Second, at the ecophysiological scale, C allocation to gain nutrients from the soil is considered and it is argued that any C limitation is only through a limitation to soil nutrient cycling. Finally, the response of forest ecosystems to rising atmospheric CO2 concentrations is considered and evidence from FACE experiments is discussed. From the three lines of evidence we conclude that the growth of trees is not C-limited, with the key to understanding future responses to climate change being turnover of soil organic matter and nutrient cycling. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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