Effect of elevated CO₂ on carbon and nitrogen distribution within a tree (Castanea sativa Mill.) - soil system

• Published in: Plant and soil 1994-05, Vol.162 (2), p.281-292
• Main Authors: Rouhier, H., Billès, G., El Kohen, A., Mousseau, M., Bottner, P.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Carbon dioxide; Forest soils; Forestry; Fundamental and applied biological sciences. Psychology; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Nitrogen; Organic soils; Plant roots; Plants; Seedlings; Soil air; Soil microorganisms; Soil respiration; Synecology; Terrestrial ecosystems
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF01347715

Two-year-old sweet chestnut trees were grown outside in normal or double CO₂ atmospheric concentration. In spring and in autumn of two growing seasons, a six day labelling pulse of 14 C labelled CO₂ was used to follow the carbon assimilation and distribution in the plant-soil system. Doubling atmospheric CO₂ had a significant effect on the tree net carbon uptake. A large proportion of the additional C uptake was 'lost' through the root system. This suggests that increased C uptake under elevated CO₂ conditions increases C cycling without necessarily increasing C storage in the plant. Total root derived material represented a significant amount of the 'extra-assimilated' carbon due to the CO₂ treatment and was strongly correlated with the phenological stage of the tree. Increasing root rhizodeposition led to a stimulation of microbial activity, particularly near the end of the growing season. When plant rhizodeposition was expressed as a function of the root dry weight, the effect of increasing CO₂ resulted in a higher root activity. The C to N ratios were significantly higher for trees grown under elevated CO₂ except for the fine root compartment. An evaluation of the plant-soil system nitrogen dynamics showed, during the second season of CO₂ treatment, a decrease of soil N mineralization rate and total N uptake for trees grown at elevated CO₂ levels.